TY - JOUR A1 - Balischewski, Christian A1 - Bhattacharyya, Biswajit A1 - Sperlich, Eric A1 - Günter, Christina A1 - Beqiraj, Alkit A1 - Klamroth, Tillmann A1 - Behrens, Karsten A1 - Mies, Stefan A1 - Kelling, Alexandra A1 - Lubahn, Susanne A1 - Holtzheimer, Lea A1 - Nitschke, Anne A1 - Taubert, Andreas T1 - Tetrahalidometallate(II) ionic liquids with more than one metal BT - the effect of bromide versus chloride JF - Chemistry - a European journal N2 - Fifteen N-butylpyridinium salts - five monometallic [C4Py](2)[MBr4] and ten bimetallic [C4Py](2)[(M0.5M0.5Br4)-M-a-Br-b] (M=Co, Cu, Mn, Ni, Zn) - were synthesized, and their structures and thermal and electrochemical properties were studied. All the compounds are ionic liquids (ILs) with melting points between 64 and 101 degrees C. Powder and single-crystal X-ray diffraction show that all ILs are isostructural. The electrochemical stability windows of the ILs are between 2 and 3 V. The conductivities at room temperature are between 10(-5) and 10(-6) S cm(-1). At elevated temperatures, the conductivities reach up to 10(-4) S cm(-1) at 70 degrees C. The structures and properties of the current bromide-based ILs were also compared with those of previous examples using chloride ligands, which illustrated differences and similarities between the two groups of ILs. KW - electrochemistry KW - ionic liquids KW - metal-containing ionic liquids; KW - N-butylpyridinium bromide KW - tetrahalidometallates Y1 - 2022 U6 - https://doi.org/10.1002/chem.202201068 SN - 1521-3765 VL - 28 IS - 64 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Bhattacharyya, Biswajit A1 - Balischewski, Christian A1 - Sperlich, Eric A1 - Günter, Christina A1 - Mies, Stefan A1 - Kelling, Alexandra A1 - Taubert, Andreas T1 - N-Butyl Pyridinium Diiodido Argentate(I) BT - A One-Dimensional Ag-I Network with Superior Solid-State Ionic Conductivity at Room Temperature JF - Advanced materials interfaces N2 - A new solid-state material, N-butyl pyridinium diiodido argentate(I), is synthesized using a simple and effective one-pot approach. In the solid state, the compound exhibits 1D ([AgI2](-))(n) chains that are stabilized by the N-butyl pyridinium cation. The 1D structure is further manifested by the formation of long, needle-like crystals, as revealed from electron microscopy. As the general composition is derived from metal halide-based ionic liquids, the compound has a low melting point of 100-101 degrees C, as confirmed by differential scanning calorimetry. Most importantly, the compound has a conductivity of 10(-6) S cm(-1) at room temperature. At higher temperatures the conductivity increases and reaches to 10(-4 )S cm(-1) at 70 degrees C. In contrast to AgI, however, the current material has a highly anisotropic 1D arrangement of the ionic domains. This provides direct and tuneable access to fast and anisotropic ionic conduction. The material is thus a significant step forward beyond current ion conductors and a highly promising prototype for the rational design of highly conductive ionic solid-state conductors for battery or solar cell applications. KW - AgI KW - ionic conductivity KW - Ionic liquids KW - thermal properties Y1 - 2023 U6 - https://doi.org/10.1002/admi.202202363 SN - 2196-7350 VL - 10 IS - 12 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Gonzalez-Chavarria, Ivan A1 - Duprat, Felix A1 - Roa, Francisco J. A1 - Jara, Nery A1 - Toledo, Jorge R. A1 - Miranda, Felipe A1 - Becerra, Jose A1 - Inostroza, Alejandro A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Heydenreich, Matthias A1 - Paz, Cristian T1 - Maytenus disticha extract and an isolated β-Dihydroagarofuran induce mitochondrial depolarization and apoptosis in human cancer cells by increasing mitochondrial reactive oxygen species JF - Biomolecules N2 - Maytenus disticha (Hook F.), belonging to the Celastraceae family, is an evergreen shrub, native of the central southern mountains of Chile. Previous studies demonstrated that the total extract of M. disticha (MD) has an acetylcholinesterase inhibitory activity along with growth regulatory and insecticidal activities. beta-Dihydroagarofurans sesquiterpenes are the most active components in the plant. However, its activity in cancer has not been analyzed yet. Here, we demonstrate that MD has a cytotoxic activity on breast (MCF-7), lung (PC9), and prostate (C4-2B) human cancer cells with an IC50 (mu g/mL) of 40, 4.7, and 5 mu g/mL, respectively, an increasing Bax/Bcl2 ratio, and inducing a mitochondrial membrane depolarization. The beta-dihydroagarofuran-type sesquiterpene (MD-6), dihydromyricetin (MD-9), and dihydromyricetin-3-O-beta-glucoside (MD-10) were isolated as the major compounds from MD extracts. From these compounds, only MD-6 showed cytotoxic activity on MCF-7, PC9, and C4-2B with an IC50 of 31.02, 17.58, and 42.19 mu M, respectively. Furthermore, the MD-6 increases cell ROS generation, and MD and MD-6 induce a mitochondrial superoxide generation and apoptosis on MCF-7, PC9, and C4-2B, which suggests that the cytotoxic effect of MD is mediated in part by the beta-dihydroagarofuran-type that induces apoptosis by a mitochondrial dysfunction. KW - Maytenus disticha KW - beta-dihydroagarofuran-type sesquiterpene KW - dihydromyricetin KW - dihydromyricetin-3-O-beta-glucoside KW - cytotoxic KW - activity KW - Mitochondrial ROS Y1 - 2020 U6 - https://doi.org/10.3390/biom10030377 SN - 2218-273X VL - 10 IS - 3 PB - MDPI CY - Basel ER - TY - JOUR A1 - Behrens, Karsten A1 - Balischewski, Christian A1 - Sperlich, Eric A1 - Menski, Antonia Isabell A1 - Balderas-Valadez, Ruth Fabiola A1 - Pacholski, Claudia A1 - Günter, Christina A1 - Lubahn, Susanne A1 - Kelling, Alexandra A1 - Taubert, Andreas T1 - Mixed chloridometallate(ii) ionic liquids with tunable color and optical response for potential ammonia sensors JF - RSC Advances N2 - Eight d-metal-containing N-butylpyridinium ionic liquids (ILs) with the nominal composition (C4Py)2[Ni0.5M0.5Cl4] or (C4Py)2[Zn0.5M0.5Cl4] (M = Cu, Co, Mn, Ni, Zn; C4Py = N-butylpyridinium) were synthesized, characterized, and investigated for their optical properties. Single crystal and powder X-ray analysis shows that the compounds are isostructural to existing examples based on other d-metal ions. Inductively coupled plasma optical emission spectroscopy measurements confirm that the metal/metal ratio is around 50 : 50. UV-Vis spectroscopy shows that the optical absorption can be tuned by selection of the constituent metals. Moreover, the compounds can act as an optical sensor for the detection of gases such as ammonia as demonstrated via a simple prototype setup. Y1 - 2022 U6 - https://doi.org/10.1039/d2ra05581c SN - 2046-2069 VL - 12 SP - 35072 EP - 35082 PB - RSC CY - London ER - TY - JOUR A1 - Kwesiga, George A1 - Kelling, Alexandra A1 - Kersting, Sebastian A1 - Sperlich, Eric A1 - von Nickisch-Rosenegk, Markus A1 - Schmidt, Bernd T1 - Total syntheses of prenylated isoflavones from Erythrina sacleuxii and their antibacterial activity BT - 5-deoxy-3′-prenylbiochanin A and erysubin F JF - Journal of natural products N2 - The prenylated isoflavones 5-deoxyprenylbiochanin A (7-hydroxy-4'-methoxy-3'-prenylisoflavone) and erysubin F (7,4'-dihydroxy-8,3'-diprenylisoflavone) were synthesized for the first time, starting from mono-or di-O-allylated chalcones, and the structure of 5-deoxy-3'-prenylbiochanin A was corroborated by single-crystal X-ray diffraction analysis. Flavanones are key intermediates in the synthesis. Their reaction with hypervalent iodine reagents affords isoflavones via a 2,3-oxidative rearrangement and the corresponding flavone isomers via 2,3-dehydrogenation. This enabled a synthesis of 7,4'-dihydroxy-8,3'-diprenylflavone, a non-natural regioisomer of erysubin F. Erysubin F (8), 7,4'-dihydroxy-8,3'-diprenylflavone (27), and 5-deoxy-3'prenylbiochanin A (7) were tested against three bacterial strains and one fungal pathogen. All three compounds are inactive against Salmonella enterica subsp. enterica (NCTC 13349), Escherichia coli (ATCC 25922), and Candida albicans (ATCC 90028), with MIC values greater than 80.0 mu M. The diprenylated natural product erysubin F (8) and its flavone isomer 7,4'-dihydroxy-8,3'diprenylflavone (27) show in vitro activity against methicillin-resistant Staphylococcus aureus (MRSA, ATCC 43300) at MIC values of 15.4 and 20.5 mu M, respectively. In contrast, the monoprenylated 5-deoxy-3'-prenylbiochanin A (7) is inactive against this MRSA strain. Y1 - 2020 U6 - https://doi.org/10.1021/acs.jnatprod.0c00932 SN - 0163-3864 SN - 1520-6025 VL - 83 IS - 11 SP - 3445 EP - 3453 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Wessig, Pablo A1 - Badetko, Dominik A1 - Czarnecki, Maciej A1 - Wichterich, Lukas A1 - Schmidt, Peter A1 - Brudy, Cosima A1 - Sperlich, Eric A1 - Kelling, Alexandra T1 - Studies toward the total synthesis of arylnaphthalene lignans via a Photo-Dehydro-Diels-Alder (PDDA) reaction JF - The journal of organic chemistry N2 - An efficient method for the preparation of arylnaphthalene lignans (ANLs) was developed, which is based on thePhoto-Dehydro-DIELS-ALDER(PDDA) reaction. While intermolecular PDDA reactions turned out to be inefficient, theintramolecular variant using suberic acid as tether linking two aryl propiolic esters smoothly provided naphthalenophanes. Theirradiations were performed with a previously developed annular continuous-flow reactor and UVB lamps. In this way, the naturalproducts Alashinol D, Taiwanin C, and an unnamed ANL could be prepared. Y1 - 2022 U6 - https://doi.org/10.1021/acs.joc.2c00195 SN - 0022-3263 SN - 1520-6904 VL - 87 IS - 9 SP - 5904 EP - 5915 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Balischewski, Christian A1 - Behrens, Karsten A1 - Zehbe, Kerstin A1 - Günter, Christina A1 - Mies, Stefan A1 - Sperlich, Eric A1 - Kelling, Alexandra A1 - Taubert, Andreas T1 - Ionic liquids with more than one metal BT - optical and rlectrochemical properties versus d-block metal vombinations JF - Chemistry - a European journal N2 - Thirteen N-butylpyridinium salts, including three monometallic [C4Py](2)[MCl4], nine bimetallic [C4Py](2)[(M1-xMxCl4)-M-a-Cl-b] and one trimetallic compound [C4Py](2)[(M1-y-zMyMz (c) Cl4)-M-a-M-b] (M=Co, Cu, Mn; x=0.25, 0.50 or 0.75 and y=z=0.33), were synthesized and their structure and thermal and electrochemical properties were studied. All compounds are ionic liquids (ILs) with melting points between 69 and 93 degrees C. X-ray diffraction proves that all ILs are isostructural. The conductivity at room temperature is between 10(-4) and 10(-8) S cm(-1). Some Cu-based ILs reach conductivities of 10(-2) S cm(-1), which is, however, probably due to IL dec. This correlates with the optical bandgap measurements indicating the formation of large bandgap semiconductors. At elevated temperatures approaching the melting points, the conductivities reach up to 1.47x10(-1) S cm(-1) at 70 degrees C. The electrochemical stability windows of the ILs are between 2.5 and 3.0 V. KW - bandgap KW - electrochemistry KW - ionic liquids KW - metal-containing ionic KW - liquids KW - tetrahalido metallates Y1 - 2020 U6 - https://doi.org/10.1002/chem.202003097 SN - 0947-6539 SN - 1521-3765 VL - 26 IS - 72 SP - 17504 EP - 17513 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Fudickar, Werner A1 - Metz, Melanie A1 - Mai-Linde, Yasemin A1 - Krüger, Tobias A1 - Kelling, Alexandra A1 - Sperlich, Eric A1 - Linker, Torsten T1 - Influence of functional groups on the ene reaction of singlet oxygen with 1,4-cyclohexadienes JF - Photochemistry and photobiology : the official journal of the American Society for Photobiology N2 - The photooxygenation of 1,4-cyclohexadienes has been studied with a special focus on regio- and stereoselectivities. In all examples, only the methyl-substituted double bond undergoes an ene reaction with singlet oxygen, to afford hydroperoxides in moderate to good yields. We explain the high regioselectivities by a "large-group effect" of the adjacent quaternary stereocenter. Nitriles decrease the reactivity of singlet oxygen, presumably by quenching, but can stabilize proposed per-epoxide intermediates by polar interactions resulting in different stereoselectivities. Spiro lactams and lactones show an interesting effect on regio- and stereoselectivities of the ene reactions. Thus, singlet oxygen attacks the double bond preferentially anti to the carbonyl group, affording only one regioisomeric hydroperoxide. If the reaction occurs from the opposite face, the other regioisomer is exclusively formed by severe electrostatic repulsion in a perepoxide intermediate. We explain this unusual behavior by the fixed geometry of spiro compounds and call it a "spiro effect" in singlet oxygen ene reactions. Y1 - 2021 U6 - https://doi.org/10.1111/php.13422 SN - 0031-8655 SN - 1751-1097 VL - 97 IS - 6 SP - 1289 EP - 1297 PB - Wiley CY - Malden, Mass. ER - TY - JOUR A1 - Schwarze, Thomas A1 - Sperlich, Eric A1 - Müller, Thomas A1 - Kelling, Alexandra A1 - Holdt, Hans-Jürgen T1 - Synthesis efforts of acyclic bis(monoalkylamino)maleonitriles and macrocyclic bis(dialkylamino)maleonitriles as fluorescent probes for cations and a new colorimetric copper(II) chemodosimeter JF - Helvetica chimica acta N2 - In this article, we report on the synthesis of acyclic bis(monoalkylamino)maleonitriles and on the intended synthesis of macrocyclic bis(dialkylamino)maleonitriles to get fluorescent probes for cations. During our efforts to synthesize macrocyclic bis(dialkylamino)maleonitriles, we were only able to isolate macrocyclic bis(dialkylamino)-fumaronitriles. The synthesis of macrocyclic bis(dialkylamino)maleonitriles is challenging, due to the fact that bis-(dialkylamino)fumaronitriles are thermodynamically more stable than the corresponding bis(dialkylamino)-maleonitriles. Further, it turned out that the acyclic bis(monoalkylamino)maleonitriles and macrocyclic bis-(dialkylamino)fumaronitriles are no suitable tools to detect cations by a strong fluorescence enhancement. Further, only the bis(monoalkylamino)maleonitriles, which are bearing a 2-pyridyl unit as an additional complexing unit, are able to selectively recognize copper(II) by a color change from yellow to red. KW - copper KW - fumaronitrile KW - ligands KW - macrocycles KW - maleonitrile Y1 - 2021 U6 - https://doi.org/10.1002/hlca.202100028 SN - 1522-2675 VL - 104 IS - 6 SP - e2100028 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schwarze, Thomas A1 - Kelling, Alexandra A1 - Sperlich, Eric A1 - Holdt, Hans-Jürgen T1 - Influence of regioisomerism in 9-anthracenyl-substituted dithiodicyanoethene derivatives on photoinduced electron transfer controlled by intramolecular charge transfer JF - ChemPhotoChem N2 - In this paper, we report on the fluorescence behaviour of three regioisomers which consist of two 9-anthracenyl fluorophores and of differently substituted dithiodicyanoethene moieties. These isomeric fluorescent probes show different quantum yields (phi(f)). In these probes, an oxidative photoinduced electron transfer (PET) from the excited 9-anthracenyl fluorophore to the dithiodicyanoethene unit quenches the fluorescence. This quenching process is accelerated by an intramolecular charge transfer (ICT) of the push-pull pi-electron system of the dithiodicyanoethene group. The acceleration of the PET depends on the strength of the ICT unit. The higher the dipole moment of the ICT unit, the stronger the observed fluorescence quenching. To the best of our knowledge, this is the first report of a regioisomeric influence on an oxidative PET by an ICT. KW - anthracene KW - charge transfer KW - electron transfer KW - fluorescence KW - isomerism Y1 - 2021 U6 - https://doi.org/10.1002/cptc.202100070 SN - 2367-0932 VL - 5 IS - 10 SP - 911 EP - 914 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Wessig, Pablo A1 - Freyse, Daniel A1 - Schuster, David A1 - Kelling, Alexandra T1 - Fluorescent dyes with large stokes shifts based on Benzo[1,2-d:4,5-d']bis([1,3]dithiole) (“S4-DBD Dyes”) JF - Europan journal of organic chemistry N2 - We report on a further development of [1,3]-dioxolo[4.5-f]benzodioxole (DBD) fluorescent dyes by replacement of the four oxygen atoms of the heterocyclic core by sulfur atoms. This variation causes striking changes of the photophysical properties. Whereas absorption and emission significantly shifted to longer wavelength, the fluorescence lifetimes and quantum yields are diminished compared to DBD dyes. The latter effect is presumably caused by an enhanced intersystem crossing to the triplet state due to the sulfur atoms. The very large Stokes shifts of the S-4-DBD dyes ranging from 3000 cm(-1) to 7400 cm(-1) (67 nm to 191 nm) should be especially emphasized. By analogy with DBD dyes a broad variation of absorption and emission wavelength is possible by introducing different electron withdrawing substituents. Moreover, some derivatives for coupling with biomolecules were developed. KW - fluorescent dyes KW - sulfur KW - heterocycles KW - stokes shift KW - photophysics Y1 - 2020 U6 - https://doi.org/10.1002/ejoc.202000093 SN - 1434-193X SN - 1099-0690 VL - 2020 IS - 11 SP - 1732 EP - 1744 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Sperlich, Eric A1 - Kelling, Alexandra A1 - Kwesiga, George A1 - Schmidt, Bernd T1 - Intermolecular interactions in the solid-state structures of isoflavones BT - the relationship between supramolecular structure, torsion angle, and macroscopic properties JF - CrystEngComm / The Royal Society of Chemistry N2 - The molecular structures of three closely related isoflavones have been determined by single crystal X-ray diffraction and have been analysed by geometry matching with the CSD, Hirshfeld surface analysis and analysis of stacking interactions with the Aromatic Analyser program (CSD). The formation of the supramolecular structure by non-covalent interactions was studied and substantial differences in the macroscopic properties e.g., the solubility, were correlated with hydrogen bonding and pi-stacking interactions. Moreover, a correlation between the supramolecular structure, the torsion angle (between benzopyran group and aryl group), and macroscopic properties was determined in the three compounds. Y1 - 2022 U6 - https://doi.org/10.1039/d2ce00169a SN - 1466-8033 VL - 24 IS - 26 SP - 4731 EP - 4739 PB - Royal Society of Chemistry CY - London ER - TY - JOUR A1 - Wessig, Pablo A1 - John, Leonard A1 - Sperlich, Eric A1 - Kelling, Alexandra T1 - Sulfur tuning of [1,3]-dioxolo[4.5-f]benzodioxole (DBD) fluorescent dyes JF - European journal of organic chemistry N2 - The replacement of oxygen by sulfur atoms of [1,3]-dioxolo[4.5-f]benzodioxole (DBD) fluorescent dyes is an efficient way to adjust the photophysical properties (sulfur tuning). While previously developed S-4-DBD dyes exhibit considerably red-shifted absorption and emission wavelength, the heavy atom effect of four sulfur atoms cause low fluorescence quantum yields and short fluorescence lifetimes. Herein, we demonstrate that the replacement of less than four sulfur atoms (S-1-DBD, 1,2-S-2-DBD, and 1,4-S-2-DBD dyes) permits a fine-tuning of the photophysical properties. In some cases, a similar influence on the wavelength without the detrimental effect on the quantum yields and lifetimes is observed. Furthermore, the synthetic accessibility of S-1- and S-2-DBD dyes is improved, compared with S-4-DBD dyes. For coupling with biomolecules a series of reactive derivatives of the new dyes were developed (azides, OSu esters, alkynes, maleimides). KW - fluorescent dyes KW - heterocycles KW - photophysics KW - stokes shift KW - sulfur Y1 - 2020 U6 - https://doi.org/10.1002/ejoc.202001418 SN - 1434-193X SN - 1099-0690 VL - 2021 IS - 3 SP - 499 EP - 511 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Krüger, Tobias A1 - Bramborg, Andrea A1 - Kelling, Alexandra A1 - Sperlich, Eric A1 - Linker, Torsten T1 - Birch Reduction of Arenes as an Easy Entry to γ-Spirolactones JF - European journal of organic chemistry N2 - A convenient method for the synthesis of γ-spirolactones in only 2–3 steps is described. Birch reduction of inexpensive and commercially available aromatic carboxylic acids in the presence of ethylene oxide affords hydroxy acids, which undergo direct lactonization during work-up. Suitable precursors are methyl-substituted benzoic acids, naphthoic, and dicarboxylic acids. Subsequent hydrogenation proceeds smoothly with Pd/C as catalyst and saturated γ-spirolactones are isolated in excellent yields and stereoselectivities. Thus, up to 3 new stereogenic centers can be constructed as sole diastereomers from achiral benzoic acids. Furthermore, it is possible to control the degree of saturation with Raney nickel or Wilkinson's catalyst to obtain products with 1 double bond. Overall, more than 30 new γ-spirolactones have been synthesized in analytically pure form. KW - Arenes KW - Birch reduction KW - Hydrogenation KW - Lactones KW - Synthetic methods Y1 - 2021 U6 - https://doi.org/10.1002/ejoc.202101018 SN - 1434-193X SN - 1099-0690 VL - 2021 IS - 46 SP - 6383 EP - 6391 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Krüger, Tobias A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Linker, Torsten T1 - Simple Synthesis of gamma-Spirolactams by Birch Reduction of Benzoic Acids JF - European journal of organic chemistry N2 - A convenient synthesis of gamma-spirolactams in only two steps was developed. Birch reduction of benzoic acids and immediate alkylation with chloroacetonitrile afforded cyclohexadienes in high yields. The products could be isolated by crystallization on a large scale in analytically pure form. Subsequent hydrogenation with platinum(IV) oxide as the catalyst reduced the nitrile functionality and the double bonds in the same step with excellent stereoselectivity. The relative configurations were determined unequivocally by X-ray analyses. Direct cyclization of the intermediary formed amino acids afforded the desired gamma-spirolactams in excellent overall yields. The procedure is characterized by few steps, cheap reagents, and can be performed on a large scale, interesting for industrial processes. KW - Diastereoselectivity KW - Hydrogenation KW - Lactams KW - Reduction KW - Synthetic methods Y1 - 2016 U6 - https://doi.org/10.1002/ejoc.201601650 SN - 1434-193X SN - 1099-0690 IS - 6 SP - 1074 EP - 1077 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Alrefai, Anas A1 - Mondal, Suvendu Sekhar A1 - Wruck, Alexander A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Brandt, Philipp A1 - Janiak, Christoph A1 - Schoenfeld, Sophie A1 - Weber, Birgit A1 - Rybakowski, Lawrence A1 - Herrman, Carmen A1 - Brennenstuhl, Katlen A1 - Eidner, Sascha A1 - Kumke, Michael Uwe A1 - Behrens, Karsten A1 - Günter, Christina A1 - Müller, Holger A1 - Holdt, Hans-Jürgen T1 - Hydrogen-bonded supramolecular metal-imidazolate frameworks: gas sorption, magnetic and UV/Vis spectroscopic properties JF - Journal of Inclusion Phenomena and Macrocyclic Chemistry N2 - By varying reaction parameters for the syntheses of the hydrogen-bonded metal-imidazolate frameworks (HIF) HIF-1 and HIF-2 (featuring 14 Zn and 14 Co atoms, respectively) to increase their yields and crystallinity, we found that HIF-1 is generated in two different frameworks, named as HIF-1a and HIF-1b. HIF-1b is isostructural to HIF-2. We determined the gas sorption and magnetic properties of HIF-2. In comparison to HIF-1a (Brunauer-Emmett-Teller (BET) surface area of 471m(2) g(-1)), HIF-2 possesses overall very low gas sorption uptake capacities [BET(CO2) surface area=85m(2) g(-1)]. Variable temperature magnetic susceptibility measurement of HIF-2 showed antiferromagnetic exchange interactions between the cobalt(II) high-spin centres at lower temperature. Theoretical analysis by density functional theory confirmed this finding. The UV/Vis-reflection spectra of HIF-1 (mixture of HIF-1a and b), HIF-2 and HIF-3 (with 14 Cd atoms) were measured and showed a characteristic absorption band centered at 340nm, which was indicative for differences in the imidazolate framework. KW - Gas-sorption KW - Ligand design KW - Magnetic properties KW - Supramolecular chemistry KW - Solvothermal synthesis Y1 - 2019 U6 - https://doi.org/10.1007/s10847-019-00926-6 SN - 1388-3127 SN - 1573-1111 VL - 94 IS - 3-4 SP - 155 EP - 165 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Grunwald, Nicolas A1 - Kelling, Alexandra A1 - Holdt, Hans-Jürgen A1 - Schilde, Uwe T1 - The crystal structure of 1,1′-bisisoquinoline, C18H12N2 JF - Zeitschrift für Kristallographie : international journal for structural, physical and chemical aspects of crystalline materials ; New crystal structures N2 - C18H12N2, tetragonal, I4(1)/a (no. 88), a = 13.8885(6) angstrom, c = 13.6718(6) angstrom, V = 2637.2(3) angstrom(3), Z = 8, R-gt(F) = 0.0295, wR(ref)(F-2) = 0.0854, T = 210 K. Y1 - 2017 U6 - https://doi.org/10.1515/ncrs-2017-0088 SN - 1433-7266 VL - 232 SP - 839 EP - 841 PB - De Gruyter CY - Berlin ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Hovestadt, Maximilian A1 - Dey, Subarna A1 - Paula, Carolin A1 - Glomb, Sebastian A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Janiak, Christoph A1 - Hartmann, Martin A1 - Holdt, Hans-Jürgen T1 - Synthesis of a partially fluorinated ZIF-8 analog for ethane/ethene separation JF - CrystEngComm N2 - The separation of ethane/ethene mixtures (as well as other paraffin/olefin mixtures) is one of the most important but challenging processes in the petrochemical industry. In this work, we report the synthesis of ZIF-318, isostructural to ZIF-8 but built from the mixed linkers of 2-methylimidazole (L1) and 2-trifluoromethylimidazole (L2) (ZIF-318 = [(Zn(L1)(L2)](n)). The synthesis has been optimized to proceed without ZnO-formation. Using only the L2 linker under solvothermal conditions afforded ZnO-embedded in the H-bonded and non-porous coordination polymer ZnO@[Zn-2(L2)(2)(HCOO)(OH)](n). The slight differences in the size of the substituents (-CH3 vs. -CF3) possibly in combination with different electronic inductive effects led to small but significant changes to the pore size and properties respectively, though the effective pore opening (aperture) size of ZIF-318 remained the same in comparison with ZIF-8. ZIF-318 is chemically (boiling water, methanol, benzene, and wide pH range at room temperature for 1 day), thermally (up to 310 degrees C) stable, and more hydrophobic than ZIF-8 which is proven by contact angle measurement. ZIF-318 can be activated for N-2, CO2, CH4, H-2, ethane, ethane, propane, and propene gases sorptions. Consequently, in breakthrough experiments, the ethane/ethene mixtures can be separated. Y1 - 2017 U6 - https://doi.org/10.1039/c7ce01438d SN - 1466-8033 VL - 19 SP - 5882 EP - 5891 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Brietzke, Thomas Martin A1 - Dietz, Thomas A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Bois, Juliana A1 - Kelm, Harald A1 - Reh, Manuel A1 - Schmitz, Markus A1 - Koerzdoerfer, Thomas A1 - Leimkühler, Silke A1 - Wollenberger, Ulla A1 - Krueger, Hans-Joerg A1 - Holdt, Hans-Jürgen T1 - The 1,6,7,12-Tetraazaperylene Bridging Ligand as an Electron Reservoir and Its Disulfonato Derivative as Redox Mediator in an Enzyme-Electrode Process JF - Chemistry - a European journal N2 - The homodinuclear ruthenium(II) complex [{Ru(l-N4Me2)}(2)(-tape)](PF6)(4) {[1](PF6)(4)} (l-N4Me2=N,N-dimethyl-2,11-diaza[3.3](2,6)-pyridinophane, tape=1,6,7,12-tetraazaperylene) can store one or two electrons in the energetically low-lying * orbital of the bridging ligand tape. The corresponding singly and doubly reduced complexes [{Ru(l-N4Me2)}(2)(-tape(.-))](PF6)(3) {[2](PF6)(3)} and [{Ru(l-N4Me2)}(2)(-tape(2-))](PF6)(2) {[3](PF6)(2)}, respectively, were electrochemically generated, successfully isolated and fully characterized by single-crystal X-ray crystallography, spectroscopic methods and magnetic susceptibility measurements. The singly reduced complex [2](PF6)(3) contains the -radical tape(.-) and the doubly reduced [3](PF6)(2) the diamagnetic dianion tape(2-) as bridging ligand, respectively. Nucleophilic aromatic substitution at the bridging tape in [1](4+) by two sulfite units gave the complex [{Ru(l-N4Me2)}(2){-tape-(SO3)(2)}](2+) ([4](2+)). Complex dication [4](2+) was exploited as a redox mediator between an anaerobic homogenous reaction solution of an enzyme system (sulfite/sulfite oxidase) and the electrode via participation of the low-energy *-orbital of the disulfonato-substituted bridging ligand tape-(SO3)(2)(2-) (E-red1=-0.1V versus Ag/AgCl/1m KCl in water). KW - electrochemistry KW - enzyme catalysis KW - N-ligands KW - redox-active ligands KW - ruthenium Y1 - 2017 U6 - https://doi.org/10.1002/chem.201703639 SN - 0947-6539 SN - 1521-3765 VL - 23 SP - 15583 EP - 15587 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Abouserie, Ahed A1 - Zehbe, Kerstin A1 - Metzner, Philipp A1 - Kelling, Alexandra A1 - Günter, Christina A1 - Schilde, Uwe A1 - Strauch, Peter A1 - Körzdörfer, Thomas A1 - Taubert, Andreas T1 - Alkylpyridinium Tetrahalidometallate Ionic Liquids and Ionic Liquid Crystals: Insights into the Origin of Their Phase Behavior JF - European journal of inorganic chemistry : a journal of ChemPubSoc Europe N2 - Six N-alkylpyridinium salts [CnPy](2)[MCl4] (n = 4 or 12 and M = Co, Cu, Zn) were synthesized, and their structure and thermal properties were studied. The [C4Py](2)[MCl4] compounds are monoclinic and crystallize in the space group P2(1)/n. The crystals of the longer chain analogues [C12Py](2)[MCl4] are triclinic and crystallize in the space group P (1) over bar. Above the melting temperature, all compounds are ionic liquids (ILs). The derivatives with the longer C12 chain exhibit liquid crystallinity and the shorter chain compounds only show a melting transition. Consistent with single-crystal analysis, electron paramagnetic resonance spectroscopy suggests that the [CuCl4](2-) ions in the Cu-based ILs have a distorted tetrahedral geometry. KW - Ionic liquids KW - Alkylpyridinium salts KW - Structure elucidation KW - Phase transitions Y1 - 2017 U6 - https://doi.org/10.1002/ejic.201700826 SN - 1434-1948 SN - 1099-0682 SP - 5640 EP - 5649 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Abouserie, Ahed A1 - Zehbe, Kerstin A1 - Metzner, Philipp A1 - Kelling, Alexandra A1 - Günter, Christina A1 - Schilde, Uwe A1 - Strauch, Peter A1 - Körzdörfer, Thomas A1 - Taubert, Andreas T1 - Alkylpyridinium Tetrahalidometallate Ionic Liquids and Ionic Liquid Crystals: Insights into the Origin of Their Phase Behavior JF - European journal of inorganic chemistry : a journal of ChemPubSoc Europe N2 - Six N-alkylpyridinium salts [CnPy](2)[MCl4] (n = 4 or 12 and M = Co, Cu, Zn) were synthesized, and their structure and thermal properties were studied. The [C4Py](2)[MCl4] compounds are monoclinic and crystallize in the space group P2(1)/n. The crystals of the longer chain analogues [C12Py](2)[MCl4] are triclinic and crystallize in the space group P (1) over bar. Above the melting temperature, all compounds are ionic liquids (ILs). The derivatives with the longer C12 chain exhibit liquid crystallinity and the shorter chain compounds only show a melting transition. Consistent with single-crystal analysis, electron paramagnetic resonance spectroscopy suggests that the [CuCl4](2-) ions in the Cu-based ILs have a distorted tetrahedral geometry. KW - Ionic liquids KW - Alkylpyridinium salts KW - Structure elucidation KW - Phase transitions Y1 - 2017 U6 - https://doi.org/10.1002/ejic.201700826 SN - 1434-1948 SN - 1099-0682 SP - 5640 EP - 5649 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Strauch, Peter A1 - Kossmann, Alexander A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - EPR on bis(1,2-dithiosquarato)cuprate(II) in the bis(1,2-dithiosquarato)nickelate(II) host lattice - structure and spectroscopy JF - Chemical papers N2 - EPR spectroscopy is a well suited analytical tool to monitor the electronic situation around paramagnetic metal centres as copper(II) and therefore the structural influences on the paramagnetic ion. 1,2-Dithiosquaratometalates are available by direct synthesis from metal salts with dipotassium-1,2-dithiosquarate and the appropriate counter cations. Synthesis and characterisation of bis(benzyltributylammonium)1,2-dithiosquaratonickelate(II), (BzlBu(3)N)(2)[Ni(dtsq)(2)], and bis(benzyltributylammonium)1,2-dithiosquaratocuprate(II), (BzlBu(3)N)(2)[Cu(dtsq)(2)], with benzyltributylammonium as the counter ion is reported and the X-ray structures of two complexes, (BzlBu(3)N)(2)[Ni(dtsq)(2)] and (BzlBu(3)N)(2)[Cu(dtsq)(2)], are presented. Both complexes, crystallising in the monoclinic space group P2(1)/c, are isostructural with only small differences in the coordination sphere due to the different metal ions. The diamagnetic nickel complex is therefore well suited as a host lattice for the paramagnetic Cu(II) complex to measure EPR for additional structural information. (c) 2015 Institute of Chemistry, Slovak Academy of Sciences KW - 1,2-dithiosquarate KW - 1,2-dithiosquaratometalate KW - X-ray structure KW - EPR spectroscopy Y1 - 2016 U6 - https://doi.org/10.1515/chempap-2015-0154 SN - 0366-6352 SN - 1336-9075 VL - 70 SP - 61 EP - 68 PB - De Gruyter CY - Berlin ER - TY - JOUR A1 - Brietzke, Thomas Martin A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Mickler, Wulfhard A1 - Holdt, Hans-Jürgen T1 - Heterodinuclear Ruthenium(II) Complexes of the Bridging Ligand 1,6,7,12-Tetraazaperylene with Iron(II), Cobalt(II), Nickel(II), as well as Palladium(II) and Platinum(II) JF - Zeitschrift für anorganische und allgemeine Chemie N2 - The first heterodinuclear ruthenium(II) complexes of the 1,6,7,12-tetraazaperylene (tape) bridging ligand with iron(II), cobalt(II), and nickel(II) were synthesized and characterized. The metal coordination sphere in this complexes is filled by the tetradentate N,N-dimethyl-2,11-diaza[3.3](2,6)-pyridinophane (L-N4Me2) ligand, yielding complexes of the general formula [(L-N4Me2)Ru(mu-tape)M(L-N4Me2)](ClO4)(2)(PF6)(2) with M = Fe {[2](ClO4)(2)(PF6)(2)}, Co {[3](ClO4)(2)(PF6)(2)}, and Ni {[4](ClO4)(2)(PF6)(2)}. Furthermore, the heterodinuclear tape ruthenium(II) complexes with palladium(II)- and platinum(II)-dichloride [(bpy)(2)Ru(-tape)PdCl2](PF6)(2) {[5](PF6)(2)} and [(dmbpy)(2)Ru(-tape)PtCl2](PF6)(2) {[6](PF6)(2)}, respectively were also prepared. The molecular structures of the complex cations [2](4+) and [4](4+) were discussed on the basis of the X-ray structures of [2](ClO4)(4)MeCN and [4](ClO4)(4)MeCN. The electrochemical behavior and the UV/Vis absorption spectra of the heterodinuclear tape ruthenium(II) complexes were explored and compared with the data of the analogous mono- and homodinuclear ruthenium(II) complexes of the tape bridging ligand. KW - N ligands KW - Ruthenium KW - Structure elucidation KW - Charge transfer KW - Electrochemistry Y1 - 2016 U6 - https://doi.org/10.1002/zaac.201500645 SN - 0044-2313 SN - 1521-3749 VL - 642 SP - 8 EP - 13 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Baier, Heiko A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Holdt, Hans-Jürgen T1 - Investigation of the Catalytic Activity of a 2-Phenylidenepyridine Palladium(II) Complex Bearing 4,5-Dicyano-1,3-bis(mesityl)imidazol-2-ylidene in the Mizoroki-Heck Reaction JF - Zeitschrift für anorganische und allgemeine Chemie N2 - The phenylidenepyridine (ppy) palladacycles [PdCl(ppy)(IMes)] (4) [IMes = 1,3-bis(mesityl) imidazol-2-ylidene] and [PdCl(ppy){(CN)(2)IMes}] (6) [(CN)(2)IMes = 4,5-dicyano-1,3-bis(mesityl) imidazol-2-ylidene] were prepared by facile two step syntheses, starting with the reaction of palladium(II) chloride with 2-phenylpyridine followed by subsequent addition of the NHC ligand to the precatalyst precursor [PdCl(ppy)](2). Suitable crystals for the X-ray analysis of the complexes 4 and 6 were obtained. It was shown that 6 has a shorter NHC-palladium bond than the IMes complex 4. The difference of the palladium carbene bond lengths based on the higher pi-acceptor strength of (CN)(2)IMes in comparison to IMes. Thus, (CN)(2)IMes should stabilize the catalytically active central palladium atom better than IMes. As a measure for the pi-acceptor strength of (CN)(2)IMes compared to IMes, the selone (CN)(2)IMes center dot Se (7) was prepared and characterized by Se-77-NMR spectroscopy. The pi-acceptor strength of 7 was illuminated by the shift of its Se-77-NMR signal. The Se-77-NMR signal of 7 was shifted to much higher frequencies than the Se-77-NMR signal of IMes center dot Se. Catalytic experiments using the Mizoroki-Heck reaction of aryl chlorides with n-butyl acrylate showed that 6 is the superior performer in comparison to 4. Using complex 6, an extensive substrate screening of 26 different aryl bromides with n-butyl acrylate was performed. Complex 6 is a suitable precatalyst for para-substituted aryl bromides. The catalytically active species was identified by mercury poisoning experiments to be palladium nanoparticles. KW - Carbene ligands KW - Heck reaction KW - Palladium KW - Selenium KW - C-C coupling Y1 - 2016 U6 - https://doi.org/10.1002/zaac.201500625 SN - 0044-2313 SN - 1521-3749 VL - 642 SP - 140 EP - 147 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Wessig, Pablo A1 - Gerngross, Maik A1 - Freyse, Daniel A1 - Bruhn, P. A1 - Przezdziak, Marc A1 - Schilde, Uwe A1 - Kelling, Alexandra T1 - Molecular Rods Based on Oligo-spiro-thioketals JF - The journal of organic chemistry N2 - We report on an extension of the previously established concept of oligospiroketal (OSK) rods by replacing a part or all ketal moieties by thioketals leading to oligospirothioketal (OSTK) rods. In this way, some crucial problems arising from the reversible formation of ketals are circumvented. Furthermore, the stability of the rods toward hydrolysis is considerably improved. To successfully implement this concept, we first developed a number of new oligothiol building blocks and improved the synthetic accessibility of known oligothiols, respectively. Another advantage of thioacetals is that terephthalaldehyde (TAA) sleeves, which are too flexible in the case of acetals can be used in OSTK rods. The viability of the OSTK approach was demonstrated by the successful preparation of some OSTK rods with a length of some nanometers. Y1 - 2016 U6 - https://doi.org/10.1021/acs.joc.5b02670 SN - 0022-3263 VL - 81 SP - 1125 EP - 1136 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Zehbe, Kerstin A1 - Kollosche, Matthias A1 - Lardong, Sebastian A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Taubert, Andreas T1 - Ionogels Based on Poly(methyl methacrylate) and Metal-Containing Ionic Liquids: Correlation between Structure and Mechanical and Electrical Properties JF - International journal of molecular sciences N2 - Ionogels (IGs) based on poly(methyl methacrylate) (PMMA) and the metal-containing ionic liquids (ILs) bis-1-butyl-3-methlimidazolium tetrachloridocuprate(II), tetrachloride cobaltate(II), and tetrachlorido manganate(II) have been synthesized and their mechanical and electrical properties have been correlated with their microstructure. Unlike many previous examples, the current IGs show a decreasing stability in stress-strain experiments on increasing IL fractions. The conductivities of the current IGs are lower than those observed in similar examples in the literature. Both effects are caused by a two-phase structure with micrometer-sized IL-rich domains homogeneously dispersed an IL-deficient continuous PMMA phase. This study demonstrates that the IL-polymer miscibility and the morphology of the IGs are key parameters to control the (macroscopic) properties of IGs. KW - microstructure KW - ionogels KW - ionic liquids KW - phase separation KW - mechanical properties KW - ionic conductivity Y1 - 2016 U6 - https://doi.org/10.3390/ijms17030391 SN - 1422-0067 VL - 17 PB - MDPI CY - Basel ER - TY - JOUR A1 - Zabel, Andre A1 - Winter, Alette A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Strauch, Peter T1 - Tetrabromidocuprates(II)-Synthesis, Structure and EPR JF - International journal of molecular sciences N2 - Metal-containing ionic liquids (ILs) are of interest for a variety of technical applications, e.g., particle synthesis and materials with magnetic or thermochromic properties. In this paper we report the synthesis of, and two structures for, some new tetrabromidocuprates(II) with several "onium" cations in comparison to the results of electron paramagnetic resonance (EPR) spectroscopic analyses. The sterically demanding cations were used to separate the paramagnetic Cu(II) ions for EPR measurements. The EPR hyperfine structure in the spectra of these new compounds is not resolved, due to the line broadening resulting from magnetic exchange between the still-incomplete separated paramagnetic Cu(II) centres. For the majority of compounds, the principal g values (g|| and g(perpendicular to)) of the tensors could be determined and information on the structural changes in the [CuBr4](2-) anions can be obtained. The complexes have high potential, e.g., as ionic liquids, as precursors for the synthesis of copper bromide particles, as catalytically active or paramagnetic ionic liquids. KW - tetrabromidocuprate(II) KW - X-ray structure KW - electron paramagnetic resonance KW - copper(II) Y1 - 2016 U6 - https://doi.org/10.3390/ijms17040596 SN - 1422-0067 VL - 17 PB - MDPI CY - Basel ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Bhunia, Asamanjoy A1 - Attallah, Ahmed G. A1 - Matthes, Philipp R. A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Müller-Buschbaum, Klaus A1 - Krause-Rehberg, Reinhard A1 - Janiak, Christoph A1 - Holdt, Hans-Jürgen T1 - Study of the Discrepancies between Crystallographic Porosity and Guest Access into Cadmium-Imidazolate Frameworks and Tunable Luminescence Properties by Incorporation of Lanthanides JF - Chemistry - a European journal N2 - An extended member of the isoreticular family of metal-imidazolate framework structures, IFP-6 (IFP=imidazolate framework Potsdam), based on cadmium metal and an in situ functionalized 2-methylimidazolate-4-amide-5-imidate linker is reported. A porous 3D framework with 1D hexagonal channels with accessible pore windows of 0.52nm has been synthesized by using an ionic liquid (IL) linker precursor. IFP-6 shows significant gas uptake capacity only for CO2 and CH4 at elevated pressure, whereas it does not adsorb N-2, H-2, and CH4 under atmospheric conditions. IFP-6 is assumed to deteriorate at the outside of the material during the activation process. This closing of the metal-organic framework (MOF) pores is proven by positron annihilation lifetime spectroscopy (PALS), which revealed inherent crystal defects. PALS results support the conservation of the inner pores of IFP-6. IFP-6 has also been successfully loaded with luminescent trivalent lanthanide ions (Ln(III)=Tb, Eu, and Sm) in a bottom-up one-pot reaction through the in situ generation of the linker ligand and in situ incorporation of photoluminescent Ln ions into the constituting network. The results of photoluminescence investigations and powder XRD provide evidence that the Ln ions are not doped as connectivity centers into the frameworks, but are instead located within the pores of the MOFs. Under UV light irradiation, Tb@IFP-6 and Eu@IFP-6 ((exc)=365nm) exhibit observable emission changes to a greenish and reddish color, respectively, as a result of strong Ln 4f emissions. KW - adsorption KW - cadmium KW - ionic liquids KW - luminescence KW - metal-organic frameworks Y1 - 2016 U6 - https://doi.org/10.1002/chem.201504757 SN - 0947-6539 SN - 1521-3765 VL - 22 SP - 6905 EP - 6913 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Steeples, Elliot A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Esposito, Davide T1 - Amino acid-derived N-heterocyclic carbene palladium complexes for aqueous phase Suzuki-Miyaura couplings JF - New journal of chemistry N2 - In this work, three ligands produced from amino acids were synthesized and used to produce five bis- and PEPPSI-type palladium-NHC complexes using a novel synthesis route from sustainable starting materials. Three of these complexes were used as precatalysts in the aqueous-phase Suzuki-Miyaura coupling of various substrates displaying high activity. TEM and mercury poisoning experiments provide evidence for Pd-nanoparticle formation stabilized in water. Y1 - 2016 U6 - https://doi.org/10.1039/c5nj03337c SN - 1144-0546 SN - 1369-9261 VL - 40 SP - 4922 EP - 4930 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Schilde, Uwe A1 - Kelling, Alexandra A1 - Umbreen, Sumaira A1 - Linker, Torsten T1 - Crystal structures of three bicyclic carbohydrate derivatives JF - Acta crystallographica, Section E, Crystallographic communications N2 - The title compounds, [(1R,3R,4R,5R,6S)-4,5-bis(acetyloxy)-7-oxo-2-oxabicyclo-[4.2.0]octan-3-yl]methyl acetate, C14H18O8, (I), [(1S,4R,5S,6R)-5-acetyloxy-7-hydroxyimino-2-oxobicyclo[4.2.0] octan-4-yl acetate, C11H15NO6, (II), and [(3aR, 5R, 6R, 7R, 7aS)-6,7-bis(acetyloxy)-2-oxooctahydropyrano[3,2-b]pyrrol-5-yl] methyl acetate, C14H19NO8, (III), are stable bicyclic carbohydrate derivatives. They can easily be synthesized in a few steps from commercially available glycals. As a result of the ring strain from the four-membered rings in (I) and (II), the conformations of the carbohydrates deviate strongly from the ideal chair form. Compound (II) occurs in the boat form. In the five-membered lactam (III), on the other hand, the carbohydrate adopts an almost ideal chair conformation. As a result of the distortion of the sugar rings, the configurations of the three bicyclic carbohydrate derivatives could not be determined from their NMR coupling constants. From our three crystal structure determinations, we were able to establish for the first time the absolute configurations of all new stereocenters of the carbohydrate rings. KW - crystal structure KW - carbohydrate derivatives KW - conformation KW - configuration Y1 - 2016 U6 - https://doi.org/10.1107/S2056989016018727 SN - 2056-9890 VL - 72 SP - 1839 EP - + PB - International Union of Crystallography CY - Chester ER - TY - JOUR A1 - Krueger, Tobias A1 - Kelling, Alexandra A1 - Linker, Torsten A1 - Schilde, Uwe T1 - Crystal structures of three cyclohexane‑based γ‑spirolactams BT - determination of configurations and conformations JF - BMC Chemistry N2 - The title compounds, 2-azaspiro[4.5]deca-1-one, C₉H₁₅NO, (1a), cis-8-methyl-2-azaspiro[4.5]deca-1-one, C₁₀H₁₇NO, (1b), and trans-8-methyl-2-azaspiro[4.5]deca-1-one, C₁₀H₁₇NO, (1c), were synthesized from benzoic acids 2 in only 3 steps in high yields. Crystallization from n-hexane afforded single crystals, suitable for X-ray diffraction. Thus, the configurations, conformations, and interesting crystal packing effects have been determined unequivocally. The bicyclic skeleton consists of a lactam ring, attached by a spiro junction to a cyclohexane ring. The lactam ring adopts an envelope conformation and the cyclohexane ring has a chair conformation. The main difference between compound 1b and compound 1c is the position of the carbonyl group on the 2-pyrrolidine ring with respect to the methyl group on the 8-position of the cyclohexane ring, which is cis (1b) or trans (1c). A remarkable feature of all three compounds is the existence of a mirror plane within the molecule. Given that all compounds crystallize in centrosymmetric space groups, the packing always contains interesting enantiomer-like pairs. Finally, the structures are stabilized by intermolecular N–H···O hydrogen bonds. KW - 2-Azaspiro[4.5]deca-1-ones KW - Cis- and trans-form KW - Configuration KW - Conformation KW - Lactams Y1 - 2019 U6 - https://doi.org/10.1186/s13065-019-0586-7 SN - 2661-801X VL - 13 IS - 69 PB - Springer International Publishing CY - Basel ER - TY - JOUR A1 - Grunwald, Nicolas A1 - Kelling, Alexandra A1 - Holdt, Hans-Jürgen A1 - Schilde, Uwe T1 - The crystal structure of 1,1′-bisisoquinoline, C18H12N2 JF - Zeitschrift für Kristallographie : international journal for structural, physical and chemical aspects of crystalline materials. New crystal structures N2 - C18H12N2, tetragonal, I41/a (no. 88), a=13.8885(6) Å, c=13.6718(6) Å, V =2637.2(3) Å3, Z =8, Rgt(F)=0.0295, wRref(F2)=0.0854, T =210 K. CCDC no.: 631823 Y1 - 2017 U6 - https://doi.org/10.1515/ncrs-2017-0088 VL - 232 IS - 5 SP - 839 EP - 841 PB - de Gruyter CY - Berlin ER - TY - JOUR A1 - Strauch, Peter A1 - Neumann, Mike A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - Bis(1,2-dithiosquarato)nickelates(II): Synthesis, Structure, EPR and Thermal Behavior JF - Acta chimica Slovenica N2 - 1,2-Dithiosquaratonickelates are available by direct synthesis from metal salts with dipotassium-1,2-dithiosquarate and the appropriate counter cations. The synthesis and characterization, including mass spectrometry, of a series 1,2-dithiosquaratonickelates(II), [Ni(dtsq)(2)](2-), with several "onium" cations is reported and the X-ray structures of two diamagnetic complexes, (HexPh(3)P)(2)[Ni(dtsq)(2)] and (BuPh3P)(2)[Ni(dtsq)(2)] with sterically demanding counter ions are presented. The diamagnetic nickel complexes have been doped as host lattices with traces of Cu(II) to measure EPR for additional structural information. The thermal behavior of this series is studied by thermogravimetry and differential thermal analysis (TG/DTA). The thermolysis in air as well as under nitrogen atmosphere of these complexes results in nickel oxide nano-particles in all cases, which are characterized by X-ray powder diffraction. KW - 1,2-Dithiosquarate,1,2-Dithiosquaratonickelate KW - X-ray structure KW - TG/DTA KW - Nickel oxide KW - EPR spectroscopy Y1 - 2015 SN - 1318-0207 SN - 1580-3155 VL - 62 IS - 2 SP - 288 EP - 296 PB - Drustvo CY - Ljubljana ER - TY - JOUR A1 - Senge, Mathias O. A1 - Dahms, Katja A1 - Holdt, Hans-Jürgen A1 - Kelling, Alexandra T1 - Porphyrin substituent regiochemistry, conformation and packing - the case of 5,10-diphenylporphyrin JF - Zeitschrift für Naturforschung : B, Chemical sciences N2 - 5,10-Disubstituted porphyrins are more recent additions to the family of meso-substituted porphyrins. A crystallographic comparison of 5,10-diphenylporphyrin with the regioisomeric 5,15-disubstituted system reveals striking differences in their conformation. In the free base porphyrins the former uses mainly out-of-plane distortion to alleviate steric strain while in-plane core elongation predominates in the latter. In contrast, the structure of the Cu(II) complex is planar and forms strong p-p aggregates with very small lateral shifts. Macroscopically, the packing is similar to that of porphyrin sponges of the 5,10,15,20-tetraphenylporphyrin type. KW - conformational analysis KW - crystal structure KW - porphyrins KW - tetrapyrroles Y1 - 2015 U6 - https://doi.org/10.1515/znb-2014-0217 SN - 0932-0776 SN - 1865-7117 VL - 70 IS - 2 SP - 119 EP - 123 PB - De Gruyter CY - Tübingen ER - TY - JOUR A1 - Baier, Heiko A1 - Kelling, Alexandra A1 - Holdt, Hans-Jürgen T1 - PEPPSI-Effect on Suzuki-Miyaura Reactions Using 4,5-Dicyano-1,3-dimesitylimidazol-2-ylidene-Palladium Complexes: A Comparison between trans-Ligands JF - European journal of inorganic chemistry : a journal of ChemPubSoc Europe N2 - The PEPPSI (Pyridine Enhanced Precatalyst Preparation, Stabilization and Initiation) complexes 12-15 with the structure [PdCl2{(CN)(2)IMes}(3-R-py)] (12: R = H; 13: R = Cl; 14: R = Br; 15: R = CN) bearing the maleonitrile-based N-heterocyclic carbene (NHC) (CN)(2)IMes ({(CN)(2)IMes}: 4,5-dicyano-1,3-dimesitylimidazol-2-ylidene) were prepared. Solid state structures of 14 and 15 were obtained. Complexes 14 and 15 adopt a slightly distorted square-planar coordination geometry in the solid state with the substituted pyridine ligand trans to the NHC. Catalytic activities of precatalysts 12-15 were studied and subsequently compared to complexes [PdCl2{(CN)(2)IMes}(PPh3)] (4) and [PdCl(dmba){(CN)(2)IMes}] (5) recently reported by our group in the Suzuki-Miyaura reaction of various aryl halides and phenylboronic acid. Reactions using previously reported [PdCl2(IMes)(py)] (IMes: 1,3-dimesitylimidazol-2-ylidene) (1) were also carried out and their results contrasted to those involving 12-15, 4 and 5. Differences in initiation rates and the catalytically active species related to the seven complexes in regards to the throw away ligand were investigated. Poisoning experiments with mercury show that palladium nanoparticles are responsible for the catalytic activity. KW - Carbene ligands KW - Palladium KW - Cross-coupling KW - Arenes Y1 - 2015 U6 - https://doi.org/10.1002/ejic.201500010 SN - 1434-1948 SN - 1099-0682 IS - 11 SP - 1950 EP - 1957 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schmidt, Bernd A1 - Elizarov, Nelli A1 - Schilde, Uwe A1 - Kelling, Alexandra T1 - Dual Role of Acetanilides: Traceless Removal of a Directing Group through Deacetylation/Diazotation and Palladium-Catalyzed C-C-Coupling Reactions JF - The journal of organic chemistry N2 - The acetamide group enables regioselective oxidative ortho-C-H activation reactions, such as Pd-catalyzed acylation. The synthetic utility of these transformations can be significantly enhanced by using the acetamide as a quasi-leaving group in a subsequent conventional Pd-catalyzed coupling or cross-coupling reaction. The concept is illustrated herein for the synthesis of o-alkenyl- and o-arylphenones, which have potential for the synthesis of arylated aromatic heterocycles. Y1 - 2015 U6 - https://doi.org/10.1021/acs.joc.5b00272 SN - 0022-3263 VL - 80 IS - 9 SP - 4223 EP - 4234 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Behrens, Karsten A1 - Kelling, Alexandra A1 - Nabein, Hans-Peter A1 - Schilde, Uwe A1 - Holdt, Hans-Jürgen T1 - Two Cd-II/Co-II-Imidazolate Coordination Polymers: Syntheses, Crystal Structures, Stabilities, and Luminescent/Magnetic Properties JF - Zeitschrift für anorganische und allgemeine Chemie N2 - Cadmium(II) based 2D coordination polymer [Cd(L1)(2)(DMF)(2)] (1) (L1 = 4,5-dicyano-2-methylimidazolate, DMF = N,N'-dimethylformamide) and 2D cobalt(II)-imidazolate framework [Co(L3)(4)] (2) (L3 = 4,5-diamide-2-ethoxyimidazolate) were synthesized under solvothermal reaction conditions. The materials were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, powder X-ray diffraction measurement (PXRD) and single-crystal X-ray diffraction. Compound 1 has hexacoordinate Cd-II ions and forms a zigzag chain-like coordination polymer structure, whereas compound 2 exhibits a 2D square grid type structure. The thermal stability analysis reveals that 2 showed an exceptional thermal stability up to 360 degrees C. Also, 2 maintained its fully crystalline integrity in boiling water as confirmed by PXRD. The solid state luminescent property of 1 was not observed at room temperature. Compound 2 showed an independent high spin central Co-II atom. KW - Cobalt KW - Cadmium KW - Coordination polymers KW - Crystal structures KW - Imidazole Y1 - 2015 U6 - https://doi.org/10.1002/zaac.201500526 SN - 0044-2313 SN - 1521-3749 VL - 641 IS - 11 SP - 1991 EP - 1997 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Bhunia, Asamanjoy A1 - Demeshko, Serhiy A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Janiak, Christoph A1 - Holdt, Hans-Jürgen T1 - Synthesis of a Co(II)-imidazolate framework from an anionic linker precursor: gas-sorption and magnetic properties JF - CrystEngComm N2 - A Co(II)-imidazolate-4-amide-5-imidate based MOF, IFP-5, is synthesized by using an imidazolate anion-based novel ionic liquid as a linker precursor under solvothermal conditions. IFP-5 shows significant amounts of gas (N-2, CO2, CH4 and H-2) uptake capacities. IFP-5 exhibits an independent high spin Co(II) centre and antiferromagnetic coupling. Y1 - 2014 U6 - https://doi.org/10.1039/c3ce42040j SN - 1466-8033 VL - 16 IS - 1 SP - 39 EP - 42 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Winter, Alette A1 - Thiel, Kerstin A1 - Zabel, Andre A1 - Klamroth, Tillmann A1 - Poeppl, Andreas A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Taubert, Andreas A1 - Strauch, Peter T1 - Tetrahalidocuprates(II) - structure and EPR spectroscopy. Part 2: tetrachloridocuprates(II) JF - New journal of chemistry N2 - We present and discuss the results of crystallographic and electron paramagnetic resonance (EPR) spectroscopic analyses of five tetrachloridocuprate(II) complexes to supply a useful tool for the structural characterisation of the [CuCl4](2-) moiety in the liquid state, for example in ionic liquids, or in solution. Bis(benzyltriethylammonium)-, bis(trimethylphenylammonium)-, bis(ethyltriphenylphosphonium)-, bis(benzyltriphenylphosphonium)-, and bis(tetraphenylarsonium) tetrachloridocuprate(II) were synthesised and characterised by elemental, IR, EPR and X-ray analyses. The results of the crystallographic analyses show distorted tetrahedral coordination geometry of all [CuCl4](2-) anions in the five complexes and prove that all investigated complexes are stabilised by hydrogen bonds of different intensities. Despite the use of sterically demanding ammonium, phosphonium and arsonium cations to obtain the separation of the paramagnetic Cu(II) centres for EPR spectroscopy no hyperfine structure was observed in the EPR spectra but the principal values of the electron Zeeman tensor, g(parallel to) and g(perpendicular to), could be determined. With these EPR data and the crystallographic parameters we were able to carry out a correlation study to anticipate the structural situation of tetrachloridocuprates in different physical states. This correlation is in good agreement with DFT calculations. Y1 - 2014 U6 - https://doi.org/10.1039/c3nj01039b SN - 1144-0546 SN - 1369-9261 VL - 38 IS - 3 SP - 1019 EP - 1030 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Bhunia, Asamanjoy A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Janiak, Christoph A1 - Holdt, Hans-Jürgen T1 - A supramolecular Co(II)(14)- metal-organic cube in a hydrogen-bonded network and a Co(II)-organic framework with a flexible methoxy substituent JF - Chemical communications N2 - The reaction of 4,5-dicyano-2-methoxyimidazole (L1) with Co(NO3)(2.) 6H(2)O under solvothermal conditions in DMF, a MOF, IFP-8 and a hydrogen-bonded network consisting of tetradecanuclear Co(II)(14)-metal organic cube (1) are achieved. 1 shows the bcu net with 14 cobalt atoms. Y1 - 2014 U6 - https://doi.org/10.1039/c3cc49698h SN - 1359-7345 SN - 1364-548X VL - 50 IS - 41 SP - 5441 EP - 5443 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Bhunia, Asamanjoy A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Janiak, Christoph A1 - Holdt, Hans-Jürgen T1 - Giant Zn-14 molecular building block in hydrogen-bonded network with permanent porosity for gas uptake JF - Journal of the American Chemical Society N2 - In situ imidazolate-4,5-diamide-2-olate linker generation leads to the formation of a [Zn-14(L2)(12)(O)-(OH)(2)(H2O)(4)] molecular building block (MBB) with a Zn-6 octahedron inscribed in a Zn-8 cube. The MBBs connect by amide-amide hydrogen bonds to a 3D robust supramolecular network which can be activated for N-2, CO2, CH4, and H-2 gas sorption. Y1 - 2014 U6 - https://doi.org/10.1021/ja410595q SN - 0002-7863 VL - 136 IS - 1 SP - 44 EP - 47 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Baier, Heiko A1 - Metzner, Philipp A1 - Körzdörfer, Thomas A1 - Kelling, Alexandra A1 - Holdt, Hans-Jürgen T1 - Efficient palladium(II) precatalysts bearing 4,5-dicyanoimidazol-2-ylidene for the Mizoroki-Heck reaction JF - European journal of inorganic chemistry : a journal of ChemPubSoc Europe N2 - The new N-heterocyclic carbene (NHC) complex [PdCl2{(CN)(2)IMes}(PPh3)] (2) ({(CN)(2)IMes}: 4,5-dicyano-1,3-dimesitylimidazol-2-ylidene) and the NHC palladacycle [PdCl(dmba){(CN)(2)IMes}] (3) (dmba: N,N-dimethylbenzylamine) have been synthesized by thermolysis of 4,5-dicyano-1,3-dimesityl-2-(pentafluorophenyl) imidazoline (1) in the presence of suitable palladium(II) precursors. The acyclic complex 2 was formed by ligand exchange using the mononuclear precursor [PdCl2(PPh3)(2)] and the palladacycle 3 was formed by cleavage of the dinuclear chloro-bridged precursor [Pd(mu-Cl)(dmba)](2). The new NHC precursor 1-benzyl-4,5-dicyano-2-(pentafluorophenyl)-3-picolylimidazoline (5) was formed by condensation of pentafluorobenzaldehyde with N-benzyl-N'-picolyldiaminomaleonitrile (4). The NHC palladacycle [PdCl2{(CN)(2)IBzPic}] (6) ({(CN)(2)IBzPic}: 1-benzyl-4,5-dicyano-3-picolylimidazol-2-ylidene) was prepared by in situ thermolysis of 5 in the presence of [PdCl2(PhCN)(2)]. The three palladium(II) complexes were characterized by NMR and IR spectroscopy, mass spectrometry and elemental analysis. In addition, the molecular structures of 2 and 3 were determined by X-ray diffraction. The pi-acidity of (CN)(2)IBzPic was compared with (CN)(2)IMes and perviously reported pi-acidic imidazol-2-ylidenes by NBO analysis. The Mizoroki-Heck (MH) reactions of various aryl halides with n-butyl acrylate were performed in the presence of complexes 2, 3 and 6. The new precatalysts showed high activity in the MH reactions giving good-to-excellent product yields with 0.1 mol-% pre-catalyst. The nature of the catalytically active species of 2, 3 and 6 was investigated by poisoning experiments with mercury and transmission electron microscopy. It was found that palladium nanoparticles formed from the precatalysts were involved in the catalytic process. KW - Homogeneous catalysis KW - Palladium KW - Cross coupling KW - Carbene ligands Y1 - 2014 U6 - https://doi.org/10.1002/ejic.201402040 SN - 1434-1948 SN - 1099-0682 IS - 18 SP - 2952 EP - 2960 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Mueller, Holger A1 - Junginger, Matthias A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Strehmel, Veronika A1 - Holdt, Hans-Jürgen T1 - Imidazolium 2-substituted 4,5-dicyanoimidazolate ionic liquids: synthesis, crystal structures and structure-thermal property relationships JF - Chemistry - a European journal N2 - Thirty six novel ionic liquids (ILs) with 1-butyl-3-methylimidazolium and 3-methyl-1-octylimidazolium cations paired with 2-substitited 4,5-dicyanoimidazolate anions (substituent at C2=chloro, bromo, methoxy, vinyl, amino, methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl and phenyl) have been synthesized and characterized by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and single-crystal X-ray crystallography. The effects of cation and anion type and structure on the thermal properties of the resulting ionic liquids, including several room temperature ionic liquids (RTILs) are examined and discussed. ILs exhibited large liquid and crystallization ranges and formed glasses on cooling with glass transition temperatures in the range of -22 to -68 degrees C. The effects of alkyl substituents of the imidazolate anion reflected the crystallization, melting points and thermal decomposition of the ILs. The Coulombic packing force, van der Waals forces and size of the anions can be considered for altering the thermal transitions. Three crystal structures of the ILs were determined and the effects of changes to the cations and anions on the packing of the structure were investigated. KW - crystal structures KW - imidazole KW - ion exchange KW - ionic liquids KW - pi-pi stacking Y1 - 2014 U6 - https://doi.org/10.1002/chem.201304934 SN - 0947-6539 SN - 1521-3765 VL - 20 IS - 26 SP - 8170 EP - 8181 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Wessig, Pablo A1 - Möllnitz, Kristian A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - Crystal structure of 1r,2c,3c,4t,5t,6t-1,2,3,4,5,6-hexakis-trimethylsilanyloxy-cyclohexane, C24H60O6Si6 JF - Zeitschrift für Kristallographie : international journal for structural, physical and chemical aspects of crystalline materials ; New crystal structures N2 - C24H60O6Si6, triclinic, P (1) over bar (no. 2), a = 11.307(2) angstrom, b = 12.159(2) angstrom, = 16.576(2) angstrom, alpha = 109.47(1)degrees, beta = 94.64(1)degrees, gamma = 111.65(1)degrees, V = 1942.3 angstrom(3), Z = 2, R-gt(F) = 0.043, wR(ref)(F-2) = 0.118, T = 210 K. Y1 - 2011 U6 - https://doi.org/10.1524/ncrs.2011.0105 SN - 1433-7266 VL - 226 IS - 2 SP - 228 EP - 230 PB - De Gruyter Oldenbourg CY - München ER - TY - JOUR A1 - Farra, Ramzi A1 - Thiel, Kerstin A1 - Winter, Alette A1 - Klamroth, Tillmann A1 - Poeppl, Andreas A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Taubert, Andreas A1 - Strauch, Peter T1 - Tetrahalidocuprates(II)-structure and EPR spectroscopy Part 1: Tetrabromidocuprates(II) JF - New journal of chemistry N2 - Tetrahalidocuprates(II) show a high degree of structural flexibility. We present the results of crystallographic and electron paramagnetic resonance (EPR) spectroscopic analyses of four new tetrabromidocuprate(II) compounds and compare the results with previously reported data. The cations in the new compounds are the sterically demanding benzyltriphenylphosphonium, methyltriphenylphosphonium, tetraphenylphosphonium, and hexadecyltrimethylammonium ions; they were used to achieve a reasonable separation of the paramagnetic Cu(II) ions for EPR spectroscopy. X-Ray crystallography shows that in all four complexes the [CuBr4](2-) units have a distorted tetrahedral coordination geometry which is in agreement with DFT calculations. The EPR hyperfine structure was not resolved. This is due to the exchange broadening resulting from still incomplete separation of the paramagnetic Cu(II) centres. Nevertheless, the principal values of the electron Zeemann tensor (g(parallel to) and g(perpendicular to)) of the complexes could be determined. A correlation of structural (X-ray) parameters with the spin density at the copper centres (DFT) is well reflected in the EPR spectra of the bromidocuprates. This enables the correlation of X-ray and EPR parameters to predict the structure of tetrabromidocuprates in physical states other than the crystalline state. As a result, we provide a method to structurally characterize [CuBr4](2-) in, for example, ionic liquids or in solution, which has important implications for e.g. catalysis or materials science. Y1 - 2011 U6 - https://doi.org/10.1039/c1nj20271e SN - 1144-0546 VL - 35 IS - 12 SP - 2793 EP - 2803 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Schmidt, Bernd A1 - Staude, Lucia A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - A Cross-Metathesis-Conjugate addition route to enantiopure gamma-Butyrolactams and gamma-Lactones from a C-2-Symmetric Precursor JF - European journal of organic chemistry N2 - A protected derivative of (3R, 4R)-hexa-1,5-diene-3,4-diol, a conveniently accessible C-2-symmetric building block, undergoes single or double cross metathesis with methyl acryl-ate. The cross metathesis products are amenable to stereoselective conjugate addition reactions and can be converted into either gamma-butyrolactones or gamma-lactams. KW - Lactams KW - Lactones KW - Oxygen heterocycles KW - Metathesis KW - Desymmetrization Y1 - 2011 U6 - https://doi.org/10.1002/ejoc.201001528 SN - 1434-193X IS - 9 SP - 1721 EP - 1727 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Dudek, Melanie A1 - Clegg, Jack K. A1 - Glasson, Christopher R. K. A1 - Kelly, Norman A1 - Gloe, Kerstin A1 - Gloe, Karsten A1 - Kelling, Alexandra A1 - Buschmann, Hans-Jürgen A1 - Jolliffe, Katrina A. A1 - Lindoy, Leonard F. A1 - Meehan, George V. T1 - Interaction of Copper(II) with Ditopic Pyridyl-beta-diketone Ligands dimeric, framework, and metallogel structures JF - Crystal growth & design : integrating the fields of crystal engineering and crystal growth for the synthesis and applications of new materials N2 - The interaction of Cu(II) with three beta-diketone ligands of type R(1)C(O)CH(2)C(O)R(2) (where R(1) = 2-, 3-, or 4-pyridyl and R(2) = C(6)H(5), respectively), HL(1)-HL(3), along with the X-ray structures and the pK(a) values of each ligand, are reported. HL(1) yields a dimeric complex of type [Cu(L(1))(2)](2). In this structure, two deprotonated HL(1) ligands coordinate in a trans planar fashion around each Cu(II) center, one oxygen from each CuL(2) unit bridges to an axial site of the second complex unit such that both Cu(II) centers attain equivalent five-coordinate square pyramidal geometries. The two-substituted pyridyl groups in this complex do not coordinate, perhaps reflecting steric factors associated with the closeness of the pyridyl nitrogen to the attached (conjugated) beta-diketonato backbone of each ligand. The remaining two Cu(II) species, derived from HL(2) and HL(3), are both coordination polymers of type [Cu(L)(2)](n) in which the terminal pyridine group of each ligand is intermolecularly linked to an adjacent copper center to generate the respective infinite structures. HL(2) was also demonstrated to form a fibrous metallogel when reacted with CuCl(2) in an acetonitrile/water mixture under defined conditions. Y1 - 2011 U6 - https://doi.org/10.1021/cg101629w SN - 1528-7483 VL - 11 IS - 5 SP - 1697 EP - 1704 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Schmidt, Bernd A1 - Hölter, Frank A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - Pd-Catalyzed arylation reactions with phenol diazonium salts application in the synthesis of diarylheptanoids JF - The journal of organic chemistry N2 - The first total synthesis of the natural product (3S,7R)-5,6-dehydro-de-O-methyl centrolobine and various analogues is reported, using a highly regio- and diastereoselective Mizoroki-Heck reaction of phenol diazonium salts and enantiopure dihydropyrans. The assigned relative configuration was confirmed by single-crystal X-ray structure analysis, but a revision of the absolute configuration is proposed based on polarimetric measurement. Y1 - 2011 U6 - https://doi.org/10.1021/jo2002787 SN - 0022-3263 SN - 1520-6904 VL - 76 IS - 9 SP - 3357 EP - 3365 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Schmidt, Bernd A1 - Berger, René A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - Pd-Catalyzed [2+2+1] coupling of alkynes and arenes phenol diazonium salts as mechanistic trapdoors JF - Chemistry - a European journal N2 - Alkynes and phenol diazonium salts undergo a Pd-catalyzed [2+2+1] cyclization reaction to spiro[4,5]decatetraene-7-ones. This structure was confirmed for one example by X-ray single-crystal structure analysis. The reaction is believed to proceed through oxidative addition of the phenol diazonium cation to Pd(0), subsequent insertion of two alkynes, followed by irreversible spirocyclization. KW - alkynes KW - diazo compounds KW - palladium KW - phenols KW - spirocycles Y1 - 2011 U6 - https://doi.org/10.1002/chem.201100609 SN - 0947-6539 VL - 17 IS - 25 SP - 7032 EP - 7040 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Brietzke, Thomas Martin A1 - Mickler, Wulfhard A1 - Kelling, Alexandra A1 - Holdt, Hans-Jürgen T1 - Mono- and dinuclear ruthenium(II) 1,6,7,12-tetraazaperylene complexes JF - Dalton transactions : a journal of inorganic chemistry, including bioinorganic, organometallic, and solid-state chemistry N2 - We report the synthesis of free 1,6,7,12-tetraazaperylene (tape). Tape was obtained from 1,1'-bis-2,7-naphthyridine by potassium promoted cyclization followed by oxidation with air. Mono-and dinuclear ruthenium(II) 1,6,7,12-tetraazaperylene complexes of the general formulas [Ru(L-L)(2)(tape)](PF6)(2), [1] (PF6)(2)-[5](PF6)(2), and [{Ru(L-L)(2)}(2)(mu-tape)](PF6)(4), [6](PF6)(4)-[10](PF6)(4), with{L-L = phen, bpy, dmbpy (4,4'-dimethyl-2,2'-bipyridine), dtbbpy (4,4'-ditertbutyl-2,2'-bipyridine) and tmbpy (4,4' 5,5'-tetramethyl-2,2'- bipyridine)}, respectively, were synthesized. The X-ray structures of tape center dot 2CHCl(3) and the mononuclear complexes [Ru(bpy)(2)(tape)](PF6)(2)center dot 0.5CH(3)CN center dot 0.5toluene, [Ru(dmbpy)(2)(tape)] (PF6)(2)center dot 2toluene and [Ru(dtbbpy)(2)(tape)](PF6)(2) center dot 3acetone center dot 0.5H(2)O were solved. The UV-vis absorption spectra and the electrochemical behavior of the ruthenium(II) tape complexes were explored and compared with the data of the analogous dibenzoeilatin (dbneil), 2,2'-bipyrimidine (bpym) and tetrapyrido [3,2-a:2',3'-c:3 '',2''-h:2''',3'''-j] phenazin (tpphz) species. Y1 - 2012 U6 - https://doi.org/10.1039/c2dt11805j SN - 1477-9226 VL - 41 IS - 9 SP - 2788 EP - 2797 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Kammer, Stefan A1 - Starke, Ines A1 - Pietrucha, Andreas A1 - Kelling, Alexandra A1 - Mickler, Wulfhard A1 - Schilde, Uwe A1 - Dosche, Carsten A1 - Kleinpeter, Erich A1 - Holdt, Hans-Jürgen T1 - 1,12-Diazaperylene and 2,11-dialkylated-1,12-diazaperylene iridium(III) complexes [Ir((CN)-N-boolean AND)(2)((NN)-N-boolean AND)]PF6: new supramolecular assemblies JF - Dalton transactions : a journal of inorganic chemistry, including bioinorganic, organometallic, and solid-state chemistry N2 - A series of new monocationic iridium(III) complexes [Ir((CN)-N-boolean AND)(2)((NN)-N-boolean AND)]PF6 with "large-surface" alpha,alpha'-diimin ligands (NN)-N-boolean AND (dap = 1,12-diazaperylene, dmedap = 2,11-dimethyl-1,12-diazaperylene, dipdap = 2,11-diisopropyl-1,12-diazaperylene) and different cyclometalating ligands (CN)-N-boolean AND (piq = 1-phenylisoquinoline, bzq = benzo[h]quinoline, ppz = 1-phenylpyrazole, thpy = 2-(2-thienyl)pyridine, ppy = 2-phenylpyridine, meppy = 2-(4-methylphenyl)pyridine, dfppy = 2-(2,4-difluorophenyl)pyridine) were synthesized. The solid structures of the complexes [Ir(piq)(2)(dap)]PF6, [Ir(bzq)(2)(dap)]PF6, [Ir(ppy)(2)(dipdap)]PF6, [Ir(piq)(2)(dmedap)]PF6, [Ir(ppy)(2)(dap)]PF6 and [Ir(ppz)(2)(dap)]PF6 are reported. In [Ir(piq)(2)(dap)]PF6, the dap ligand and one of the piq ligands of each cationic complex are involved in pi-pi stacking interactions forming supramolecular channels running along the crystallographic c axis. In the crystalline [Ir(bzq)(2)(dap)]PF6 pi-pi stacking interactions between the metal complexes lead to the formation of a 2D layer structure. In addition, CH-pi interactions were found in all compounds, which are what stabilizes the solid structure. In particular, a significant number of them were found in [Ir(piq)(2)(dap)]PF6 and [Ir(bzq)(2)(dap)]PF6. The crystal structures of [Ir(ppy)(2)(dipdap)]PF6 and [Ir(ppy)(2)(dmedap)]PF6 are also presented, being the first examples of bis-cyclometalated iridium(III) complexes with phenanthroline-type alpha,alpha'-diimin ligands bearing bulky alkyl groups in the neighbourhood of the N-donor atoms. These ligands implicate a distorted octahedral coordination geometry that in turn destabilized the Ir-N-N boolean AND N bonds. The new iridium (III) complexes are not luminescent. All compounds show an electrochemically irreversible anodic peak between 1.15 and 1.58 V, which is influenced by the different cyclometalated ligands. All of the new complexes show two reversible successive one-electron "large-surface" ligand-centred reductions around -0.70 V and -1.30 V. Electrospray ionisation mass spectrometry (ESI-MS) and collision induced decomposition (CID) measurements were used to investigate the stability of the new complexes. Thereby, the stability agreed well with the order of the Ir-N-N boolean AND N bond lengths. Y1 - 2012 U6 - https://doi.org/10.1039/c2dt30412k SN - 1477-9226 VL - 41 IS - 34 SP - 10219 EP - 10227 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Schmidt, Bernd A1 - Krehl, Stefan A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - Synthesis of 8-Aryl-Substituted Coumarins based on Ring-Closing Metathesis and Suzuki-Miyaura coupling - synthesis of a Furyl Coumarin natural product from Galipea panamensis JF - The journal of organic chemistry N2 - The synthesis of 7-methoxy-8-(4-methyl-3-furyl)-2H-chromen-2-one, a natural product with antileishmanial activity recently isolated from the plant Galipea panamensis, is described. The key step is a Suzuki-Miyaura coupling of a furan-3-boronic acid and an 8-halocoumarin, which is advantageously synthesized using a ring-closing metathesis reaction. Several non-natural analogues are also available along these lines. Y1 - 2012 U6 - https://doi.org/10.1021/jo2026564 SN - 0022-3263 VL - 77 IS - 5 SP - 2360 EP - 2367 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Träger, Juliane A1 - Klamroth, Tillmann A1 - Kelling, Alexandra A1 - Lubahn, Susanne A1 - Cleve, Ernst A1 - Mickler, Wulfhard A1 - Heydenreich, Matthias A1 - Müller, Holger A1 - Holdt, Hans-Jürgen T1 - Complexation of Palladium(II) with unsaturated Dithioethers a systematic development of highly selective ligands for solvent extraction JF - European journal of inorganic chemistry : a journal of ChemPubSoc Europe N2 - There is a demand for new and robust PdII extractants due to growing recycling rates. Chelating dithioethers are promising substances for solvent extraction as they form stable square-planar complexes with PdII. We have modified unsaturated dithioethers, which are known to coordinate PdII, and adapted them to the requirements of industrial practice. The ligands are analogues of 1,2-dithioethene with varying electron-withdrawing backbones and polar end-groups. The crystal structures of several ligands and their palladium complexes were determined as well as their electro- and photochemical properties, complex stability and behaviour in solution. Solvent extraction experiments showed the superiority of some of our ligands over conventionally used extractants in terms of their very fast reaction rates. With highly selective 1,2-bis(2-methoxyethylthio)benzene (4) it is possible to extract PdII from a highly acidic medium in the presence of other base and palladium-group metals. KW - Renewable resources KW - Palladium KW - Chelates KW - Ligand design KW - S li-gands Y1 - 2012 U6 - https://doi.org/10.1002/ejic.201101406 SN - 1434-1948 IS - 14 SP - 2341 EP - 2352 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schwarze, Thomas A1 - Kelling, Alexandra A1 - Müller, Holger A1 - Trautmann, Michael A1 - Klamroth, Tillmann A1 - Baumann, Otto A1 - Strauch, Peter A1 - Holdt, Hans-Jürgen T1 - N-2-Pyridinylmethyl-N '-arylmethyl-diaminomaleonitriles: New Highly Selective Chromogenic Chemodosimeters for Copper(II) JF - Chemistry - a European journal KW - amides KW - chemodosimeter KW - colorimetric detection KW - copper KW - sensors KW - UV KW - Vis spectroscopy Y1 - 2012 U6 - https://doi.org/10.1002/chem.201201731 SN - 0947-6539 VL - 18 IS - 34 SP - 10506 EP - 10510 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Debatin, Franziska A1 - Behrens, Karsten A1 - Weber, Jens A1 - Baburin, Igor A. A1 - Thomas, Arne A1 - Schmidt, Johannes A1 - Senkovska, Irena A1 - Kaskel, Stefan A1 - Kelling, Alexandra A1 - Hedin, Niklas A1 - Bacsik, Zoltan A1 - Leoni, Stefano A1 - Seifert, Gotthard A1 - Jäger, Christian A1 - Günter, Christina A1 - Schilde, Uwe A1 - Friedrich, Alwin A1 - Holdt, Hans-Jürgen T1 - An isoreticular family of microporous metal-organic frameworks based on zinc and 2-substituted imidazolate-4-amide-5-imidate Syntheses, structures and properties JF - Chemistry - a European journal N2 - We report on a new series of isoreticular frameworks based on zinc and 2-substituted imidazolate-4-amide-5-imidate (IFP-14, IFP=imidazolate framework Potsdam) that form one-dimensional, microporous hexagonal channels. Varying R in the 2-substitued linker (R=Me (IFP-1), Cl (IFP-2), Br (IFP-3), Et (IFP-4)) allowed the channel diameter (4.01.7 angstrom), the polarisability and functionality of the channel walls to be tuned. Frameworks IFP-2, IFP-3 and IFP-4 are isostructural to previously reported IFP-1. The structures of IFP-2 and IFP-3 were solved by X-ray crystallographic analyses. The structure of IFP-4 was determined by a combination of PXRD and structure modelling and was confirmed by IR spectroscopy and 1H MAS and 13C CP-MAS NMR spectroscopy. All IFPs showed high thermal stability (345400?degrees C); IFP-1 and IFP-4 were stable in boiling water for 7 d. A detailed porosity analysis was performed on the basis of adsorption measurements by using various gases. The potential of the materials to undergo specific interactions with CO2 was investigated by measuring the isosteric heats of adsorption. The capacity to adsorb CH4 (at 298 K), CO2 (at 298 K) and H2 (at 77 K) at high pressure were also investigated. In situ IR spectroscopy showed that CO2 is physisorbed on IFP-14 under dry conditions and that both CO2 and H2O are physisorbed on IFP-1 under moist conditions. KW - adsorption KW - metal- organic frameworks KW - microporous materials KW - N KW - O ligands KW - zinc Y1 - 2012 U6 - https://doi.org/10.1002/chem.201200889 SN - 0947-6539 VL - 18 IS - 37 SP - 11630 EP - 11640 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Brietzke, Thomas Martin A1 - Mickler, Wulfhard A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Krüger, Hans-Joerg A1 - Holdt, Hans-Jürgen T1 - Mono- and dinuclear Ruthenium(II)-1,6,7,12-Tetraazaperylene complexes of N,N '-Dimethyl-2,11-diaza[3.3](2,6)-pyridinophane JF - European journal of inorganic chemistry : a journal of ChemPubSoc Europe N2 - Ruthenium(II) complexes [Ru(L-N4Me2)(dape)](PF6)2 {[1](PF6)2}, [Ru(L-N4Me2)(tape)](PF6)2 {[2](PF6)2}, and [{Ru(L-N4Me2)}2(mu-tape)](PF6)4 {[3](PF6)4} were synthesized in two reaction steps by first reacting [Ru(DMSO)4Cl2] with tetraazamacrocyclic ligand N,N'-dimethyl-2,11-diaza[3.3](2,6)-pyridinophane (L-N4Me2) in ethanol under microwave irradiation to the intermediate [Ru(L-N4Me2)Cl2], which was subsequently, without further isolation, reacted with 1,12-diazaperylene (dape) or 1,6,7,12-tetraazaperylene (tape). X-ray structures of [Ru(L-N4Me2)(dape)](PF6)2, [Ru(L-N4Me2)(tape)](PF6)2.acetone, and [{Ru(L-N4Me2)}2(mu-tape)](ClO4)4.MeCN were determined. The UV/Vis absorption spectra of [1](PF6)2, [2](PF6)2, and [3](PF6)4 in acetonitrile display intense low-energy dp(Ru)?p* (dape or tape) MLCT absorption bands centered at 579, 637, and 794 nm, respectively. Reversible metal oxidations for the bimetallic complex [{Ru(L-N4Me2)}2(mu-tape)]4+ ([3]4+) are detected at 1.69 and 1.28 V vs. SCE. The potential difference ?E = 410 mV and the intervalence-charge-transfer (IVCT) transition at 2472 nm indicate a high degree of electronic interaction between the two ruthenium ions mediated through the tape bridging ligand. All three complexes, [1]2+, [2]2+, and [3]4+, were characterized by UV/Vis spectroelectrochemistry. The monooxidized and monoreduced states, [1]3+, [2]3+, [3]5+, and [1]+, [2]+, [3]3+, are accessible by reversible one-electron oxidation and one-electron reduction processes, respectively, as documented by the observation of several stable isosbestic points in the spectral progressions. The second reduction in each complex and the second oxidation in [3]4+ prove to be irreversible in these spectroelectrochemical experiments. Monoreduced species [1]+, [2]+, and [3]3+ yield EPR signals indicating that the unpaired electron is mainly centered on the large surface ligands dape or tape. KW - Ruthenium KW - Macrocyclic li-gands KW - N ligands KW - Redox chemistry KW - Mixed-valent compounds Y1 - 2012 U6 - https://doi.org/10.1002/ejic.201200667 SN - 1434-1948 IS - 29 SP - 4632 EP - 4643 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Bhunia, Asamanjoy A1 - Baburin, Igor A. A1 - Jäger, Christian A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Seifert, Gotthard A1 - Janiak, Christoph A1 - Holdt, Hans-Jürgen T1 - Gate effects in a hexagonal zinc-imidazolate-4-amide-5-imidate framework with flexible methoxy substituents and CO2 selectivity JF - Chemical communications N2 - A new imidazolate-4-amide-5-imidate based MOF, IFP-7, is generated, having flexible methoxy groups, which act as molecular gates for guest molecules. This allows highly selective CO2 sorption over N-2 and CH4 gases. Y1 - 2013 U6 - https://doi.org/10.1039/c3cc42156b SN - 1359-7345 VL - 49 IS - 69 SP - 7599 EP - 7601 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Dey, Subarna A1 - Baburin, Igor A. A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Seifert, Gotthard A1 - Janiak, Christoph A1 - Holdt, Hans-Jürgen T1 - Syntheses of two imidazolate-4-amide-5-imidate linker-based hexagonal metal-organic frameworks with flexible ethoxy substituent JF - CrystEngComm N2 - A rare example of in situ linker generation with the formation of soft porous Zn- and Co-MOFs (IFP-9 and -10, respectively) is reported. The flexible ethoxy groups of IFP-9 and -10 protrude into the 1D hexagonal channels. The gas-sorption behavior of both materials for H-2, CO2 and CH4 showed wide hysteretic isotherms, typical for MOFs having a flexible substituent which can give rise to a gate effect. Y1 - 2013 U6 - https://doi.org/10.1039/c3ce41632a SN - 1466-8033 VL - 15 IS - 45 SP - 9394 EP - 9399 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Wessig, Pablo A1 - Matthes, Annika A1 - Schilde, Uwe A1 - Kelling, Alexandra T1 - Asymmetric synthesis of (1,5)Naphthalenophanes by Dehydro-Diels-Alder reaction JF - European journal of organic chemistry N2 - An asymmetric variant of the dehydro-Diels-Alder (DDA) reaction has been developed and applied in the atropselective synthesis of various (1,5)naphthalenophanes. Whereas the suitability of the photochemically induced DDA (PDDA) was limited, the thermally induced DDA provided the desired product, depending on the chiral auxiliary used and the length of the linker, with nearly perfect stereoselectivity. Furthermore, the mechanism of the DDA was investigated by means of DFT calculations, and a stepwise mechanism involving 1,4-biradicals was suggested. KW - Synthetic methods KW - Macrocycles KW - Cyclophanes KW - Atropisomerism KW - Chiral auxiliaries KW - Density functional calculations Y1 - 2013 U6 - https://doi.org/10.1002/ejoc.201201594 SN - 1434-193X IS - 11 SP - 2123 EP - 2129 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Linker, Torsten A1 - Bramborg, Andrea A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - Crystal structure of trans-1,4-di-(2-(allyloxyethyl)-cyclohexa-2,5-diene-1,4-dicarboxylic acid, C18H24O6 JF - Zeitschrift für Kristallographie : international journal for structural, physical and chemical aspects of crystalline materials ; New crystal structures N2 - C18H24O6, triclinic, P (1) over bar (no. 2), a = 5.726(1) angstrom, b = 8.845(2) angstrom, c = 9.557(2) angstrom, alpha = 105.27(1)degrees, beta = 102.76(1)degrees, gamma = 103.49(1)degrees, V = 433.0 angstrom(3), Z = 1, R-gt(F) = 0.0412, wR(ref)(F-2) = 0.1075, T = 210 K. Y1 - 2013 U6 - https://doi.org/10.1524/ncrs.2013.0124 SN - 1433-7266 VL - 228 IS - 2 SP - 243 EP - 244 PB - De Gruyter Oldenbourg CY - München ER - TY - JOUR A1 - Linker, Torsten A1 - Fudickar, Werner A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - Crystal structure of dimethyl 1,4-dioxaspiro[4,5]dec-6-ene-(8R)-[(3,5-dinitrobenzoyl)oxa]-(2R,3R)-dica rboxylate, C19H18N2O12 JF - Zeitschrift für Kristallographie : international journal for structural, physical and chemical aspects of crystalline materials ; New crystal structures N2 - C19H18N2O12, orthorhombic, P2(1)2(1)2(1) (no. 19), a = 6.2472(6) angstrom, b = 17.576(2) angstrom, c = 18.848(3) angstrom, V = 2069.6 angstrom(3), Z = 4, R-gt(F) = 0.0393, wR(ref)(F-2) = 0.0694, T = 210 K. Y1 - 2013 U6 - https://doi.org/10.1524/ncrs.2013.0123 SN - 1433-7266 VL - 228 IS - 2 SP - 241 EP - 242 PB - De Gruyter Oldenbourg CY - München ER - TY - JOUR A1 - Baier, Heiko A1 - Kelling, Alexandra A1 - Jackstell, Ralf A1 - Holdt, Hans-Jürgen T1 - Rhodium(I) and Silver(I) Complexes of 4,5-Dicyano-1,3-dimesityl- and 4,5-Dicyano-1,3-dineopentylimidazol-2-ylidene JF - Zeitschrift für anorganische und allgemeine Chemie N2 - The new N-heterocyclic carbene (NHC) precursors 4,5-dicyano-1, -dimesityl- (9) and 4, 5-dicyano-1, 3-dineopentyl-2-(pentafluorophenyl)imidazoline (14) were synthesized. 9 could be determined by X-ray crystallography. With the 2-pentafluorophenyl-substituted imidazolines 9 and 14, the [AgCl(NHC)], [RhCl(COD)(NHC)], and [RhCl(CO)(2)(NHC)] complexes [NHC = 4, 5-dicyano-1, 3-dimesitylimidazol-2-ylidene (3) and 4, 5-dicyano-1, 3-dineopentylimidazol-2-ylidene (4)] were obtained. Crystal structures of [AgCl(3)] (15), [RhCl(COD)(3)] (17), [RhCl(COD)(4)] (18), and [RhCl(CO)(2)(3)] (19) were solved and with the crystal data of 19, the percent buried volume (%V-bur) of 31.8(+/- 0.1)% was determined for NHC 3. Infrared spectra of the imidazolines 9 and 14 and of the complexes 15-20 were recorded and the CO stretching frequencies of complexes 19 and 20 were used to determine the 3 ( (-1)) and 4 ( (-1)), thus proving that 1, 3-substitution of maleonitrile-NHCs does not have a significant effect for the high -acceptor strength of these carbenes. KW - Carbenes KW - Rhodium KW - Silver KW - Crystal structure KW - Diaminomaleonitrile Y1 - 2013 U6 - https://doi.org/10.1002/zaac.201300250 SN - 0044-2313 SN - 1521-3749 VL - 639 IS - 10 SP - 1731 EP - 1739 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schwarze, Thomas A1 - Traeger, Juliane A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Holdt, Hans-Jürgen T1 - Macrocyclic dithiomaleonitriles for an efficient PdCl2 coordination JF - Inorganica chimica acta : the international inorganic chemistry journal N2 - We have synthesized a set of new unsaturated macrocyclic dithioethers with an increasing number of flexible methylene units 1-7 (Scheme 2) to investigate the correlation between the ring size of these ligands, the chelation effect and the consequences for an efficient PdCl2 coordination. The dithioethers 1-7 and the complex [PdCl2(4)]center dot CHCl3 were characterized by X-ray diffraction analysis. The crystal structures of 1-7 show that 2-7 are better preorganized chelating ligands for an exocyclic PdCl2 coordination than 1. The chelation effect of 1-7, the orientation of the sulfur atoms and the S center dot center dot center dot S donor distances, are influenced by the flexibility of the methylene units. In this series the unsaturated macrocyclic ligands 5 and 6 are the best chelating ligands for an efficient PdCl2 coordination. Comparative solvent extraction experiments with mn-12S(2)O(2) (mn = maleonitrile) reveal that the low interface activity of the new ligands reduces the extraction rate. However, a comparison with open-chain dithiomaleonitriles shows the impact of the macrocyclic effect of 4 and 5 on the extraction yield. KW - Thioether ligands KW - Palladium KW - Synthesis KW - X-ray diffraction KW - Chelation effect KW - Extraction Y1 - 2013 U6 - https://doi.org/10.1016/j.ica.2013.08.020 SN - 0020-1693 SN - 1873-3255 VL - 408 IS - 2 SP - 53 EP - 58 PB - Elsevier CY - Lausanne ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Bhunia, Asamanjoy A1 - Demeshok, Serhiy A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Janiak, Christoph A1 - Holdt, Hans-Jürgen T1 - Synthesis of a Co(II)-imidazolate framework from an anionic linker precursor: gas-sorption ans magnetic proberties N2 - A Co(II)-imidazolate-4-amide-5-imidate based MOF, IFP-5, is synthesized by using an imidazolate anion-based novel ionic liquid as a linker precursor under solvothermal conditions. IFP-5 shows significant amounts of gas (N2, CO2, CH4 and H2) uptake capacities. IFP-5 exhibits an independent high spin Co(II) centre and antiferromagnetic coupling. Y1 - 2008 UR - http://pubs.rsc.org/en/content/articlelanding/2013/ce/c3ce42040j ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Dey, Subarna A1 - Baburin, Igor A. A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Janiak, Christoph A1 - Holdt, Hans-Jürgen T1 - Syntheses of two imidazolate-4-amide-5-imidate linker based hexagonal metal-organic frameworks with flexible ethoxy substituent N2 - A rare example of in situ linker generation with the formation of soft porous Zn- and Co-MOFs (IFP-9 and -10, respectively) is reported. The flexible ethoxy groups of IFP-9 and -10 protrude into the 1D hexagonal channels. The gas- sorption behavior of both materials for H2, CO2 and CH4 showed wide hysteretic isotherms, typical for MOFs having a flexible substituent which can give rise to a gate effect. Y1 - 2008 UR - http://pubs.rsc.org/en/Content/ArticleLanding/2013/CE/c3ce41632a U6 - https://doi.org/10.1039/C3CE41632A ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Bhunia, Asamanjoy A1 - Baburin, Igor A. A1 - Jäger, Christian A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Seiert, Gotthard A1 - Janiak, Christoph A1 - Holdt, Hans-Jürgen T1 - Gate effects in a hexagonal zinc-imidazolate-4-amide-5-imidate framework with flexible methoxy substituents and CO2 selectivity N2 - A new imidazolate-4-amide-5-imidate based MOF, IFP-7, is generated, having flexible methoxy groups, which act as molecular gates for guest molecules. This allows highly selective CO2 sorption over N2 and CH4 gases. Y1 - 2008 UR - http://pubs.rsc.org/en/content/articlepdf/2013/cc/c3cc42156b U6 - https://doi.org/10.1039/C3CC42156B ER - TY - JOUR A1 - Rudershausen, S. A1 - Drexler, Hans-Joachim A1 - Banße, Wolfgang A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Holdt, Hans-Joachim T1 - Three polymorphs of bis(5-methylthio-1,2-dithiole-3-thione)-disulfide N2 - The title compound, bis(5-methylthio-1,2-dithiole-3-thione)-disulfide, was yielded for the first time as by- product of the reaction of nickel(II) and cobalt(II) ions with 5-methylthio-1,2-dithiole-3-thione-4-thiolate. The compound can be obtained directly by oxidation of the ammonium salt of the ligand. C8H6S10 forms three polymorphs: (I), which crystallizes in the orthorhombic space group P212121, (II) and (III), which crystallize in the monoclinic space groups P21/c and P21/n, respectively. The crystal and molecular structures are presented here. The determination of the absolute configuration of (I) indicated the P-helical enantiomer. In contrast to this, the crystals of (II) und (III) are racemic, containing P- and M-helical enantiomers. The polymorphs differ in the kind of skewing around the disulfide bond and of the positions of the both dithiole rings to the S-S-moiety Y1 - 2007 UR - http://onlinelibrary.wiley.com/doi/10.1002/crat.200610776/pdf U6 - https://doi.org/10.1002/crat.200610776 ER - TY - JOUR A1 - Meshcheryakov, Vladimir I. A1 - Moskalik, Mikail Yu. A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Ushakov, Igor A. A1 - Shainyan, Bagrat A. T1 - Oxymethylation of trifluoromethanesulfonamide with paraformaldehyde in ethyl acetate N2 - Acid-catalyzed reaction of trifluoromethanesulfonamide with paraformaldehyde in ethyl acetate led to the formation of oxymethylated products that did not form in the reaction carried out in sulfuric acid. Following products were obtained: 5-trifluoromethylsulfonyl-1,3-dioxazinane, 3,7-bis-(trifluoromethylsulfonyl)-1,5,3,7-dioxadiazocane, and a complex of trifluoromethanesulfonamide with 2,4,8,10-tetraoxospiro[5,5]undecene, 1:1. The spiroring resulted from the cyclization of pentaerythritol under the action of formaldehyde. The pentaerythritol formed in its turn by oxymethylation of the methyl group of ethyl acetate with paraformaldehyde followed by the reduction of the COOEt group into CH2 OH by the formaldehyde. Y1 - 2008 UR - http://springer.metapress.com/content/q58m84577ng74p3g/ ?p=0be1219998b44c288f855f33f6168bf6&pi=19 U6 - https://doi.org/10.1134/S1070428008020206 SN - 1070-4280 ER - TY - JOUR A1 - Schmidt, Bernd A1 - Werner, Frank A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - The reaction of 3,4-dihydro-2H-pyran with oxalyl chloride : formation and crystal structure analysis of an unexpected bicyclic product N2 - 3,4-Dihydro-2-H-pyran and oxalyl chloride react, depending on the conditions, to keto esters, a pyran-3- carboxylic acid or derivatives thereof, or to an hitherto unknown bicyclic acetal containing a vinyl chloride moiety. The structure of the latter product has been unambiguously elucidated by single-crystal X-ray structure analysis. A mechanism for its formation is proposed. Y1 - 2010 UR - 1960 = dx.doi.org/10.1002/jhet.456 SN - 0022-152X ER - TY - JOUR A1 - Debatin, Franziska A1 - Thomas, Arne A1 - Kelling, Alexandra A1 - Hedin, Niklas A1 - Bacsik, Zoltan A1 - Senkovska, Irena A1 - Kaskel, Stefan A1 - Junginger, Matthias A1 - Müller, Holger A1 - Schilde, Uwe A1 - Jäger, Christian A1 - Friedrich, Alwin A1 - Holdt, Hans-Jürgen T1 - In situ synthesis of an imidazolate-4-amide-5-imidate ligand and formation of a microporous zinc-organic framework with H2-and CO2-storage ability N2 - Narrow channels with polar walls are the structural and functional features responsible for the high capacity of a zinc-organic framework based on an imidazolate-amide-imidate ligand for the uptake of H2 and CO2 (see structure: orange Zn, blue N, red O, dark gray C, light gray H). The rigid and stable chelating ligand was synthesized in situ by partial hydrolysis of a dicyanoimidazole compound. Y1 - 2010 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/26737/ U6 - https://doi.org/10.1002/anie.200906188 SN - 1433-7851 ER - TY - JOUR A1 - Schwarze, Thomas A1 - Mueller, Holger A1 - Dosche, Carsten A1 - Klamroth, Tillmann A1 - Mickler, Wulfhard A1 - Kelling, Alexandra T1 - Luminescence detection of open-shell transition-metal ions by photoinduced electron transfer controlled by internal charge transfer of a receptor Y1 - 2007 UR - http://onlinelibrary.wiley.com/doi/10.1002/ange.200603992/pdf U6 - https://doi.org/10.1002/anie.200603992 ER - TY - JOUR A1 - Kammer, Stefan A1 - Kelling, Alexandra A1 - Baier, Heiko A1 - Mickler, Wulfhard A1 - Dosche, Carsten A1 - Rurack, Knut A1 - Kapp, Andreas A1 - Lisdat, Fred A1 - Holdt, Hans-Jürgen T1 - 2,11-dialkylated 1,12-diazaperylene copper(I) complexes : first supramolecular column assemblies by pi-pi stacking between homoleptic tetrahedral metal complexes, exhibiting low-energy MLCT transitions N2 - 2,11-Dialkylated 1,12-diazaperylenes (alkyl = Me, Et, iPr) dmedap, detdap and dipdap have been synthesized by reductive cyclization of 3,3-dialkylated 1,1-biisoquinolines 3a-c, resulting in the first copper(I) complexes of a large- surface ligand. The new copper(I) complexes show low-energy MLCT absorptions unprecedented for bis(-diimin)copper(I) complexes. The solid structures of the complexes[Cu(dipdap)2]BF4·CH2Cl2·1.5H2O, [Cu(dipdap)2]OTf·CH2Cl2, [Cu(dipdap)2]I·C2H4Cl2·THF·2H2O, [Cu(dmedap)2]OTf and [Cu(dipdap)2]AQSO3·H2O (AQSO3 = sodium 9,10-dihydro-9,10-dioxo-2- anthracenesulfonate) are reported. In [Cu(dipdap)2]BF4·CH2Cl2·1.5H2O, each copper(I) complex cation interacts with two others by - stacking interactions forming a novel supramolecular column structural motif running along the crystallographic c axis. In the crystalline compound [Cu(dipdap)2]AQSO3·H2O, aggregation between two complex cations and two additional anions by - stacking interactions is observed, leading to a tetrameric assembly. Furthermore, the three complex compounds [Cu(L)2]BF4 (L = dmedap, detdap, dipdap) were tested for sensory applications in aqueous buffer solutions in electrochemical studies of the complex immobilized on glassy carbon electrodes. Y1 - 2009 UR - http://www3.interscience.wiley.com/journal/27721/home U6 - https://doi.org/10.1002/ejic.200900695 SN - 1434-1948 ER - TY - JOUR A1 - Müller, Holger A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Holdt, Hans-Jürgen T1 - Ag(I)-, Hg(II)- und Pt(II)-Komplexe von Maleonitril-thiakronenethern BT - Silber(II)-, Quecksilber(II)- und Platin(II)-Komplexe von Maleonitril-thiakronenethern N2 - The synthesis and single crystal X-ray structures of eight AgI, HgII, and PtII complexes with the thiacrown ethers maleonitrile-tetrathia-12-crown-4 (mn12S4), maleonitrile-tetrathia-13-crown-4 (mn13S4), and maleonitrile- pentathia-15-crown-5 (mn15S5) (1) are reported. The ligand mn15S5 was synthesized for the first time and characterized by X-ray diffraction. With silver(I) perchlorate and silver(I) tetrafluoroborate it forms the chiral complexes [Ag(mn15S5)]ClO4·CH3NO2 (2) and [Ag(mn15S5)]BF4·CH3NO2·0.25H2O (3) with half-sandwich moieties. AgI is located in a distorted tetrahedral coordination environment, involving three sulfur atoms of the crown cycle and a fourth one of the adjacent half-sandwich moiety, forming a helical structure. The reaction of Hg(ClO4)2 with mn13S4 yielded the dinuclear complex [Hg2(mn13S4)3](ClO4)4 (4) containing two half-sandwich moieties with a third ligand molecule as a bridging unit. Mercury(II) chloride and mercury(II) iodide react with mn12S4 and mn13S4 to form complexes of the general composition [HgX2(L)] (X = Cl, I; L = mn12S4, mn13S4): [HgCl2(mn12S4)] (5), [HgI2(mn12S4)] (6), [HgCl2(mn13S4)] (7) or [HgX2(L)2] (X = I; L = mn13S4): [HgI2(mn13S4)2] (8). Only one or two sulfur atoms of the ligand are involved in the complexation, and chain or ribbon structures are formed. In these compounds the HgX2 units (X = Cl, I) are preserved, coordinated by sulfur atoms of bridging mn12S4 or mn13S4 ligands. In all complexes of this type, the metal atoms are not coordinated inside the cavity, but in an exocyclic mode, because the diameter of the macrocycle is too small. Additionally, the PtCl2 complex of mn12S4 was investigated, where PtII is coordinated in an exocyclic mode forming the complex [PtCl2(mn12S4)] (9). Two of the four sulfur atoms of the macrocycle are bonded to the metal giving together with both chlorine atoms a square-planar coordination geometry. Together with a long-range interaction with a further sulfur atom of the macrocycle a square-pyramidal coordination environment is formed. Y1 - 2009 UR - http://www.znaturforsch.com/rb/s64b1003.pdf SN - 0932-0776 ER - TY - THES A1 - Elamparuthi, Elangovan A1 - Linker, Torsten A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - Crystal structure of methyl 3,4,6-tri-O-benzyl-2-deoxy-2-C-nitromethyl-beta-D-galactopyranoside, C29H33NO7 Y1 - 2009 UR - http://www.oldenbourg.de/verlag/zkristallogr/mn-ncsc.htm U6 - https://doi.org/10.1524/ncrs.2009.0054 SN - 1433-7266 ER - TY - JOUR A1 - Elamparuthi, Elangovan A1 - Linker, Torsten A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - Crystal structure of methyl 3,4-di-O-benzyl-2-deoxy-2-C-nitromethyl-alpha-D-arabinopyranoside, C21H25NO6 Y1 - 2009 UR - http://www.oldenbourg.de/verlag/zkristallogr/mn-ncsc.htm U6 - https://doi.org/10.1524/ncrs.2009.0027 SN - 1433-7266 ER - TY - JOUR A1 - Zehm, Daniel A1 - Fudickar, Werner A1 - Hans, Melanie A1 - Schilde, Uwe A1 - Kelling, Alexandra A1 - Linker, Torsten T1 - 9,10-Diarylanthracenes as molecular switches : syntheses, properties, isomerisations and their reactions with singlet oxygen N2 - A series of 9,10-diarylanthracenes with various substituents at the ortho positions have been synthesised by palladium-catalysed cross-coupling reactions. Such compounds exhibit interesting physical properties and can be applied as molecular switches. Despite the high steric demand of the substituents, products were formed in moderate-to-good yields. In some cases, microwave conditions further improved yields. Bis-coupling afforded two isomers (syn and anti) that do not interconvert at room temperature. These products were easily separated and their relative stereochemistries were unequivocally assigned by NMR spectroscopy and X-ray analysis. The syn and anti isomers exhibit different physical properties (e.g., melting points and solubilities) and interconversion by rotation around the aryl-aryl axis commences at <100 °C for fluoro-substituted diarylanthracenes and at >300 °C for alkyl- or alkoxy-substituted diarylanthracenes. The reactions with singlet oxygen were studied separately and revealed different reactivities and reaction pathways. The yields and reactivities depend on the size and electronic nature of the substituents. The anti isomers form the same 9,10-endoperoxides as the syn species, occasionally accompanied by unexpected 1,4-endoperoxides as byproducts. Thermolysis of the endoperoxides exclusively yielded the syn isomers. The interesting rotation around the aryl-aryl axis allows the application of 9,10-diarylanthracenes as molecular switches, which are triggered by light and air under mild conditions. Finally, the oxygenation and thermolysis sequence provides a simple, synthetic access to a single stereoisomer (syn) from an unselective coupling step. Y1 - 2008 SN - 0947-6539 ER - TY - JOUR A1 - Shainyan, Bagrat A. A1 - Meshcheryakov, Vladimir I. A1 - Sterkhova, I. V. A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - Structure of the molecule of 1,2-bis(1-ethyl-1 H -1,2,3-triazol-4-yl)diazene 1-oxide in the crystal and in solutions N2 - Reduction of 4-nitro-1-ethyl-1H-1,2,3-triazole with aluminum in alkaline medium resulted in a syn-isomer of 1,2- bis(1-ethyl-1H-1,2,3-triazol-4-yl)diazene 1-oxide. The latter according to the data of X-ray diffraction analysis existed in the crystal as the most stable s-cis,s-trans-conformer, and in solution, as showed NMR data, as a mixture of s-cis,s-trans- and s-trans,s-trans-conformers. The data of quantum-chemical calculations are in agreement with the results of the structural studies. Y1 - 2008 UR - http://springer.metapress.com/content/p210730742rh4117/ SN - 1070-4280 ER - TY - JOUR A1 - Venkatraman, S. A1 - Kumar, R. A1 - Sankar, J. A1 - Chandrashekar, T. K. A1 - Sendhil, K. A1 - Vijayan, C. A1 - Kelling, Alexandra A1 - Senge, Mathias O. T1 - Oxasmaragdyrin-ferrocene and oxacorrole-ferrocene conjugates : Synthesis, structure, and nonlinear optical properties N2 - Ferrocenyl macrocyclic conjugates involving 22pi oxasmaragdyrins and 18pi oxacorroles have been synthesized and characterized. The direct covalent linkage of the ferrocenyl moiety to the meso position of the macrocycle is achieved by simple oxidative coupling of appropriate precursors with trifluoroacetic acid as catalyst. The electronic coupling between the ferrocenyl moiety and the macrocyclic pi system is apparent from: a) the red shifts (293-718 cm(-1)) of the Soret and Q-bands in the electronic absorption spectra of ferrocenyl conjugates; b) the shift of oxidation potentials (50 130 mV) of both the ferrocene and the corrole rings to the positive potentials; and c) considerable shortening of the C-C bond which connects the ferrocene and the meso-carbon atom of the macrocycle. The single-crystal X-ray structure of oxasmaragdyrin-ferrocene conjugate 9 reveals the planarity of the 22pi skeleton with very small deviations of the meso-carbon atoms. The meso-ferrocenyl substituent has a small dihedral angle of 38degrees, making way for mixing of the molecular orbitals of the ferrocene and the macrocycle. However, the other two meso substituents are almost perpendicular to the mean plane, defined by the three meso carbon atoms. Classical C-(HO)-O-... and nonclassical C- H(...)pi interactions lead to a two-dimensional supramolecular network. Ferrocene-smaragdyrin conjugate 9 bonds to a chloride ion in the protonated form and a rhodium(i) ion in the free base form. Nonlinear optical measurements reveal a larger nonlinear refractive index (-5.83 x 10(-8) cm(2) W-1) and figure of merit (2.28 x 10(-8) cm(3)W(-1)) for the rhodium smaragdyrin-ferrocene conjugate 19 than for the others, suggesting its possible application in optical devices Y1 - 2004 SN - 0947-6539 ER - TY - JOUR A1 - Senge, Mathias O. A1 - Hatscher, S. S. A1 - Wiehe, A. A1 - Dahms, Katja A1 - Kelling, Alexandra T1 - The dithianyl group as a synthon in porphyrin chemistry : condensation reactions and preparation of formylporphyrins under basic conditions Y1 - 2004 SN - 0002-7863 ER - TY - JOUR A1 - Siebold, M. A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Strauch, Peter T1 - Heterobimetallic 3d-4-complexes with bis(1;2-dithiooxalato)nickelate(II) as planar bridging block N2 - Planar bis(1,2-dithiooxalato)nickelates(II) react in aqueous solutions of lanthanide ions to form pentanuclear, heterobimetallic complexes of the general composition [{Ln(H2O)(n)}(2)- {Ni(dto)(2)}(3)] (.) xH(2)O (Ln = Y3+, La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+, Lu3+; n = 4 or 5; x = 9-12). With [{Nd(H2O)(5)}(2){Ni(S2C2O2)(2)}(3)] (.) xH(2)O (x = 10-12) (1) and [{Er(H2O)(4)}(2){Ni(S2C2O2)(2)}(3)] (.) xH(2)O (x = 9- 10) (2) we were able to isolate two complexes of this series as single crystals, which were characterized by X-ray structure analysis. Depending on the individual ionic radii of the lanthanide ions, the compounds crystallize in two different crystal systems with the following unit cell parameters: 1, monoclinic in P2(1)/c with a = 11.3987(13), b = 11.4878(8), c = 20.823(2)angstrom , beta = 98.907(9)degrees and Z = 2; 2, triclinic in P (1) over bar with a = 10.5091(6), b = 11.0604(6), c = 11.2823(6) angstrom, alpha = 107.899(4)degrees, beta = 91.436(4)degrees, gamma = 112.918(4)degrees and Z = 1. The channels and cavities appearing in the packing of the molecules are occupied by uncoordinated water molecules. High magnetic moments up to 14.65 BM./f.u. have been observed at room temperature due to the combined moments of the individual lanthanide ions Y1 - 2005 SN - 0932-0776 ER - TY - JOUR A1 - Klinka, Karel D. A1 - Balentova, Eva A1 - Bernát, Juraj A1 - Imrich, Ján A1 - Vavrusová, Martina A1 - Pihlaja, Kalevi A1 - Koch, Andreas A1 - Kleinpeter, Erich A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - Structural revision of products resulting from the reaction of methylhydrazine with acridin-9-yl isothiocyanate due to unexpected acridinyl migration And further reactions N2 - The reaction of methyl acridin-9-ylthiosemicarbazide under basic conditions with methyl bromoacetate resulted in a 1,3-thiazolin-4-one structure as provided by X-ray crystallography. The structure forced a re-evaluation of the reactant methyl acridin-9-ylthiosemicarbazide, originally thought to be 2-methyl 4-acridin-9-ylthiosemicarbazide based on synthetic expectations, but which when examined by X-ray crystallography was found to be in fact the isomeric 2- methyl 1-acridin-9-ylthiosemicarbazide resulting from rearrangement via a spiro form which it is in equilibrium with in solution. The product resulting from reaction with methyl iodide was also studied and the previously reported semicarbazide produced by reaction with MNO was re-examined. In both cases, the 1,2 isomer rather than the 2,4 isomer was found to be present based on the sign of the 3JCH3,N11 coupling. Full characterization of the compounds was rendered by 1H, 13C, and 15N solution-state NMR, and in the solid state, by both 13C and 15N NMR. Y1 - 2006 UR - http://arkat-usa.org/home.aspx?VIEW=BROWSE&MENU=ARKIVOC SN - 1551-7004 ER - TY - JOUR A1 - Holdt, Hans-Jürgen A1 - Müller, Holger A1 - Kelling, Alexandra A1 - Drexler, Hans-Joachim A1 - Müller, Thomas A1 - Schwarze, Thomas A1 - Schilde, Uwe A1 - Starke, Ines T1 - Mercury(II) chloride and iodide complexes of dithia- and tetrathiacrown ethers N2 - The complexes [(HgCl2)(2)((ch)(2)30S(4)O(6))] (1), [HgCl,(mn21S(2)O(5))] (2), [HgCl2(ch18S(2)O(4))] (3) and [HgI(meb12S(2)O(2))](2)[Hg2I6] (4) have been synthesized, characterized and their crystal structures were determined. In [(HgCl2)(2)((ch)(2)3OS(4)O(6))] two HgCl2 units are discretely bonded within the ligand cavity of the 30-membered dichinoxaline-tetrathia-30-crown-10 ((ch)(2)30S(4)O(6)) forming a binuclear complex. HgCl2 forms I : I "in-cavity" complexes with the 21-membered maleonitrile-dithia-21-crown-7(mn21S(2)O(5)) ligand and the 18-membered chinoxaline- dithia-18-crown-6 (ch18S(2)O(4)) ligand, respectively. The 12-membered 4-methyl-benzo-dithia-12-crown-4 (meb12S(2)O(2)) ligand gave with two equivalents HgI2 the compound [HgI(meb12S(2)O(2))](2)[Hg2I6]. In the cation [HgI(meb12S(2)O(2))](+) meb12S(2)O(2) forms with the cation HgI+ a half-sandwich complex Y1 - 2006 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/10005159 U6 - https://doi.org/10.1002/zaac.200500281 SN - 0044-2313 ER - TY - JOUR A1 - Kammer, Stefan A1 - Müller, Holger A1 - Grunwald, Nicolas A1 - Bellin, Anja A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Mickler, Wulfhard A1 - Dosche, Carsten A1 - Holdt, Hans-Jürgen T1 - Supramolecular assemblies with honeycomb structures by pi-pi stacking of octahedral metal complexes of 1,12- diazaperylene N2 - Homoleptic Ni-II and Fe-II complexes of the "large-surface" phenanthroline-type ligand 1,12-diazaperylene (dap), [Ni(dap)(3)](BF4)(2) (1) and [Fe(dap)(3)](PF6)(2) (2), respectively, were synthesized. In the crystal structure the complex cation [M(dap)(3)](2+) (M = Ni, Fe) exhibits C-3 symmetry and interacts with three other cations by pi-pi stacking. It forms a new metalla-supramolecular assembly with a honeycomb structure containing nanochannels running parallel to the crystallographic c axis. Aggregation by pi-pi stacking between metal complexes of "large-surface" ligands should give new perspectives for inorganic supramolecular chemistry. Y1 - 2006 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/27721/ U6 - https://doi.org/10.1002/ejic.200600092 SN - 1343-1948 ER - TY - JOUR A1 - Holdt, Hans-Jürgen A1 - Müller, Holger A1 - Potter, Matthias A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Starke, Ines A1 - Heydenreich, Matthias A1 - Kleinpeter, Erich T1 - The first sandwich complex with an octa(thioether) coordination sphere : Bis(maleonitrile-tetrathia-12-crown- 4)silver(I) N2 - The new tetrathiacrown ethers maleonitrile-tetrathia-12-crown-4 (mn12S(4)) and maleonitrile-tetrathia-13-crown- 4 (mn13S(4)) have been prepared and characterised by X-ray crystallographic analysis. These crown ethers form 2:1, 3:2 and 1: 1 complexes with AgY (Y = BF4, PF6). The crystal structures of [Ag(mn12S(4))(2)]BF4 (3a), [Ag(mn13S(4))(2)]BF4 (4a) and [Ag-2(mn13S(4))(3)](PF6)(2) (6b) have been determined. Compound 3a contains the centrosymmetric sandwich complex cation [Ag(mn12S(4))(2)](+) where each mn12S(4) ligand is coordinated to the Ag centre in an endo manner through all four S atoms. The 2:1 complex [Ag(mn12S(4))(2)](+) is the first sandwich complex with a tetrathiacrown ether and the first complex with an octa(thioether) coordination sphere. The crystal structure of compound 4a also reveals a 2:1 complex. This complex, [Ag(mnl3S(4))(2)](+), exhibits a half-sandwich structure. One mn13S(4) ligand coordinates to Ag+ by all four S donor atoms and the other 13S(4) crown by only one S atom. Compound 6b contains a dinuclear Ag complex. The Ag complexes 3a,b-8a,b were also studied by electrospray ionisation mass spectrometry. Collision-induced dissociation (CID) was used to compare the relative stability of 2:1 complexes [AgL2]+ and 1:1 complexes [AgL](+) (L = mn12S(4), mn13S(4)). The C-13 NMR chemical shifts of 2:1 and 1:1 Ag complexes and their corresponding free ligands were also estimated and compared. The free energy of the barrier of ring inversion (Delta G(double dagger)) for [Ag(mn12S(4))(2)](+) was determined to be 64 kJmol(-1). Y1 - 2006 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/27721/ U6 - https://doi.org/10.1002/ejic.200501109 SN - 1434-1948 ER - TY - JOUR A1 - Hahn, Simone A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Holdt, Hans-Jürgen T1 - Crystal structure of bis(2-ethylthiomethylpyridine)platinum(II) hexachloroplatinate, [Pt(C8H11NS)2][PtCl6] N2 - C16H22Cl6N2Pt2S2, orthorhombic, Pbca (no. 61), a = 15.5660(8) angstrom, b = 17.4892(9) angstrom, c = 18.161 (1) angstrom, V = 4944. 1 angstrom(3), Z = 8, R-gt(F) = 0.030, wR(ref)(F-2) = 0.055, T = 210 K. Y1 - 2008 UR - http://zkrist_ncs.cpfs.mpg.de/pdf223-4/216_1267-2377.pdf U6 - https://doi.org/10.1524/ncrs.2008.0216 SN - 1433-7266 ER - TY - JOUR A1 - Schilde, Uwe A1 - Kelling, Alexandra A1 - Umbreen, Sumaira A1 - Linker, Torsten T1 - Crystal structures of three bicyclic carbohydrate derivatives JF - Acta crystallographica Section E ; Crystallographic communications N2 - The title compounds, [(1R,3R,4R,5R,6S)-4,5-bis(acetyloxy)-7-oxo-2-oxabicyclo- [4.2.0]octan-3-yl]methyl acetate, C14H18O8, (I), [(1S,4R,5S,6R)-5-acetyloxy-7- hydroxyimino-2-oxobicyclo[4.2.0]octan-4-yl acetate, C11H15NO6, (II), and [(3aR,5R,6R,7R,7aS)-6,7-bis(acetyloxy)-2-oxooctahydropyrano[3,2-b]pyrrol-5- yl]methyl acetate, C14H19NO8, (III), are stable bicyclic carbohydrate derivatives. They can easily be synthesized in a few steps from commercially available glycals. As a result of the ring strain from the four-membered rings in (I) and (II), the conformations of the carbohydrates deviate strongly from the ideal chair form. Compound (II) occurs in the boat form. In the five-membered lactam (III), on the other hand, the carbohydrate adopts an almost ideal chair conformation. As a result of the distortion of the sugar rings, the configurations of the three bicyclic carbohydrate derivatives could not be determined from their NMR coupling constants. From our three crystal structure determinations, we were able to establish for the first time the absolute configurations of all new stereocenters of the carbohydrate rings. KW - crystal structure KW - carbohydrate deriv­atives KW - conformation KW - configuration Y1 - 2016 U6 - https://doi.org/10.1107/S2056989016018727 SN - 2056-9890 VL - 72 IS - 12 SP - 1839 EP - 1844 PB - IUCR CY - Chester ER - TY - JOUR A1 - Zabel, André A1 - Winter, Alette A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Strauch, Peter T1 - Tetrabromidocuprates(II)-Synthesis, Structure and EPR JF - International journal of molecular sciences N2 - Metal-containing ionic liquids (ILs) are of interest for a variety of technical applications, e.g., particle synthesis and materials with magnetic or thermochromic properties. In this paper we report the synthesis of, and two structures for, some new tetrabromidocuprates(II) with several “onium” cations in comparison to the results of electron paramagnetic resonance (EPR) spectroscopic analyses. The sterically demanding cations were used to separate the paramagnetic Cu(II) ions for EPR measurements. The EPR hyperfine structure in the spectra of these new compounds is not resolved, due to the line broadening resulting from magnetic exchange between the still-incomplete separated paramagnetic Cu(II) centres. For the majority of compounds, the principal g values (g|| and gK) of the tensors could be determined and information on the structural changes in the [CuBr4]2- anions can be obtained. The complexes have high potential, e.g., as ionic liquids, as precursors for the synthesis of copper bromide particles, as catalytically active or paramagnetic ionic liquids. KW - tetrabromidocuprate(II) KW - X-ray structure KW - electron paramagnetic resonance KW - copper(II) Y1 - 2016 U6 - https://doi.org/10.3390/ijms17040596 VL - 17 IS - 4 PB - MDPI CY - Basel ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Bhunia, Asamanjoy A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Janiak, Christoph A1 - Holdt, Hans-Jürgen T1 - A supramolecular Co(II)₁₄-metal–organic cube in a hydrogen-bonded network and a Co(II)–organic framework with a flexible methoxy substituent JF - Chemical communications : ChemComm N2 - The reaction of 4,5-dicyano-2-methoxyimidazole (L1) with Co(NO3)2·6H2O under solvothermal conditions in DMF, a MOF, IFP-8 and a hydrogen-bonded network consisting of tetradecanuclear Co(II)14-metal organic cube (1) are achieved. 1 shows the bcu net with 14 cobalt atoms. KW - zinc Y1 - 2014 U6 - https://doi.org/10.1039/c3cc49698h SN - 2046-2069 VL - 2014 IS - 41 SP - 5441 EP - 5443 PB - Royal Society of Chemistry ER -