TY - JOUR A1 - Hahn, Simone A1 - Träger, Juliane A1 - Holdt, Hans-Jürgen T1 - Solid-Phase extraction of Pt(IV) with Dialkyl-(hexane-1,6-diyl) phosphate modified merrifield resins from aqueous chloride media in column operations JF - Separation and purification technology N2 - A series of three dialkyl phosphate resins with a Merrifield resin support was used to extract platinum from acidic media. In column operations total capacities of 85-130 mg/g were gained. The presence of palladium and rhodium results in the order: Pt(IV) > Pd(II) >> Rh(III). From a leach liquor gained from spent automotive catalysts metals forming anionic chloro complexes are co-extracted only to a small extent. However, in order to separate and enrich platinum a selective back-extraction can be done with a sodium thiocyanate solution. A second elution step with acidic thiourea leads to a mixed solution of palladium and rhodium. KW - platinum KW - column operation mode KW - phosphate KW - solid-phase extraction Y1 - 2015 U6 - https://doi.org/10.1080/01496395.2014.968264 SN - 0149-6395 SN - 1520-5754 VL - 50 IS - 2 SP - 191 EP - 206 PB - Taylor & Francis Group CY - Philadelphia 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 - Attenberger, Bianca A1 - Moussa, Mehdi El Sayed A1 - Brietzke, Thomas Martin A1 - Vreshch, Volodimir A1 - Holdt, Hans-Jürgen A1 - Lescop, Christophe A1 - Scheer, Manfred T1 - Discrete Polymetallic Arrangements of Ag-I and Cu-I Ions Based on Multiple Bridging Phosphane Ligands and pi-pi Interactions JF - European journal of inorganic chemistry : a journal of ChemPubSoc Europe N2 - A simple and straightforward approach to new polymetallic Ag-I and Cu-I supramolecules is presented. The reaction of N,P,N,P,N ligand 2 with Ag-I ions affords a trimetallic complex bearing a triangular Ag-3 core; metallophilic interactions are stabilized by ligands that display a multiple bridging coordination mode as 10-electron donors. Heteroleptic polymetallic Ag-I and Cu-I complexes based on ligand 2 and the 1,12-diazaperylene (dape) ligand are obtained by an alternative molecular organization of the polymetallic arrays compared to that in homoleptic complexes of ligand 2. KW - Heterocycles KW - N KW - P ligands KW - Pi interactions KW - Polyaromatic fragments KW - Supramolecular chemistry Y1 - 2015 U6 - https://doi.org/10.1002/ejic.201500445 SN - 1434-1948 SN - 1099-0682 IS - 18 SP - 2934 EP - 2938 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Trautmann, Michael A1 - Holdt, Hans-Jürgen T1 - Separation of platinum and ruthenium by a sulphoxide modified polystyrene resin in laboratory column systems JF - Separation and purification technology N2 - The present study deals with the adsorption performance of fixed bed columns using powdered sulphoxide modified poly(styrene-co-divinylbenzene) (d(10) < 13 mu m, d(50) < 30 mu m, d(90) < 50 mu m) for the separation of platinum and ruthenium from hydrochloric acidic solutions containing both metals (c(Pt) = 20 mg/L, c(Ru) = 10 mg/L). The influence of hydrochloric acid concentration, temperature, flow rate, flow direction, redox potential and bed height on the breakthrough characteristics was examined. Platinum was separately adsorbed mainly induced by hydrochloric acid concentration and redox potential keeping platinum as Pt-IV and ruthenium as Ru-III. Ruthenium was separately adsorbed to 90% essentially induced by hydrochloric acid concentration, temperature and redox potential keeping platinum as Pt-IV and ruthenium predominantly as Ru-IV. Experimental data at optimised separation conditions were fitted to different kinetic models (Thomas, Yoon-Nelson, Bohart-Adams, Wolborska) to characterise the fixed bed column behaviour. Adsorption of both metals was well described by Thomas and Yoon-Nelson model with correlation coefficients R-2 >= 0.95 whereas Bohart-Adams and Wolborska model were less suitable. (C) 2015 Elsevier B.V. All rights reserved. KW - Solid-phase extraction KW - Platinum group metals KW - Sulphoxide KW - Breakthrough curve KW - Kinetic model Y1 - 2015 U6 - https://doi.org/10.1016/j.seppur.2015.05.013 SN - 1383-5866 SN - 1873-3794 VL - 149 SP - 279 EP - 287 PB - Elsevier CY - Amsterdam 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 - Schwarze, Thomas A1 - Riemer, Janine A1 - Eidner, Sascha A1 - Holdt, Hans-Jürgen T1 - A Highly K+-Selective Two-Photon Fluorescent Probe JF - Chemistry - a European journal N2 - A highly K+-selective two-photon fluorescent probe for the in vitro monitoring of physiological K+ levels in the range of 1-100 mM is reported. The two-photon excited fluorescence (TPEF) probe shows a fluorescence enhancement (FE) by a factor of about three in the presence of 160 mM K+, independently of one-photon (OP, 430 nm) or two-photon (TP, 860 nm) excitation and comparable K+-induced FEs in the presence of competitive Na+ ions. The estimated dissociation constant (K-d) values in Na+-free solutions (K-d(OP)=(28 +/- 5) mM and K-d(TP)=(36 +/- 6) mM) and in combined K+/Na+ solutions (K-d(OP)=(38 +/- 8) mM and K-d(TP)=(46 +/- 25) mM) reflecting the high K+/Na+ selectivity of the fluorescent probe. The TP absorption cross-section (sigma(2PA)) of the TPEF probe+160 mMK(+) is 26 GM at 860 nm. Therefore, the TPEF probe is a suitable tool for the in vitro determination of K+. KW - click chemistry KW - fluorescence KW - fluorescent probes KW - potassium KW - two-photon Y1 - 2015 U6 - https://doi.org/10.1002/chem.201501473 SN - 0947-6539 SN - 1521-3765 VL - 21 IS - 32 SP - 11306 EP - 11310 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Behrens, Karsten A1 - Matthes, Philipp R. A1 - Schönfeld, Fabian A1 - Nitsch, Jörn A1 - Steffen, Andreas A1 - Primus, Philipp-Alexander A1 - Kumke, Michael Uwe A1 - Müller-Buschbaum, Klaus A1 - Holdt, Hans-Jürgen T1 - White light emission of IFP-1 by in situ co-doping of the MOF pore system with Eu3+ and Tb3+ JF - Journal of materials chemistry : C, Materials for optical and electronic devices N2 - Co-doping of the MOF 3∞[Zn(2-methylimidazolate-4-amide-5-imidate)] (IFP-1 = Imidazolate Framework Potsdam-1) with luminescent Eu3+ and Tb3+ ions presents an approach to utilize the porosity of the MOF for the intercalation of luminescence centers and for tuning of the chromaticity to the emission of white light of the quality of a three color emitter. Organic based fluorescence processes of the MOF backbone as well as metal based luminescence of the dopants are combined to one homogenous single source emitter while retaining the MOF's porosity. The lanthanide ions Eu3+ and Tb3+ were doped in situ into IFP-1 upon formation of the MOF by intercalation into the micropores of the growing framework without a structure directing effect. Furthermore, the color point is temperature sensitive, so that a cold white light with a higher blue content is observed at 77 K and a warmer white light at room temperature (RT) due to the reduction of the organic emission at higher temperatures. The study further illustrates the dependence of the amount of luminescent ions on porosity and sorption properties of the MOF and proves the intercalation of luminescence centers into the pore system by low-temperature site selective photoluminescence spectroscopy, SEM and EDX. It also covers an investigation of the border of homogenous uptake within the MOF pores and the formation of secondary phases of lanthanide formates on the surface of the MOF. Crossing the border from a homogenous co-doping to a two-phase composite system can be beneficially used to adjust the character and warmth of the white light. This study also describes two-color emitters of the formula Ln@IFP-1a–d (Ln: Eu, Tb) by doping with just one lanthanide Eu3+ or Tb3+. Y1 - 2015 U6 - https://doi.org/10.1039/C4TC02919D SN - 2050-7534 SN - 2050-7526 VL - 18 IS - 3 SP - 4623 EP - 4631 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Behrens, Karsten A1 - Matthes, Philipp R. A1 - Schönfeld, Fabian A1 - Nitsch, Jörn A1 - Steffen, Andreas A1 - Primus, Philipp-Alexander A1 - Kumke, Michael Uwe A1 - Müller-Buschbaum, Klaus A1 - Holdt, Hans-Jürgen T1 - White light emission of IFP-1 by in situ co-doping of the MOF pore system with Eu3+ and Tb3+ JF - Journal of materials chemistry : C, Materials for optical and electronic devices Y1 - 2015 U6 - https://doi.org/10.1039/c4tc02919d SN - 2050-7526 SN - 2050-7534 VL - 3 IS - 18 SP - 4623 EP - 4631 PB - Royal Society of Chemistry CY - Cambridge ER - TY - GEN A1 - Mondal, Suvendu Sekhar A1 - Marquardt, Dorothea A1 - Janiak, Christoph A1 - Holdt, Hans-Jürgen T1 - Use of a 4,5-dicyanoimidazolate anion based ionic liquid for the synthesis of iron and silver nanoparticles N2 - Sixteen new ionic liquids (ILs) with tetraethylammonium, 1-butyl-3-methylimidazolium, 3-methyl-1-octylimidazolium and tetrabutylphosphonium cations paired with 2-substituted 4,5-dicyanoimidazolate anions (substituent at C2 = methyl, trifluoromethyl, pentafluoroethyl, N,N′-dimethyl amino and nitro) have been synthesized and characterized by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA). The effects of cation and anion type and structure of the resulting ILs, including several room temperature ionic liquids (RTILs), are reflected in the crystallization, melting points and thermal decomposition of the ILs. ILs exhibited large liquid and crystallization ranges and formed glasses on cooling with glass transition temperatures in the range of −22 to −71 °C. We selected one of the newly designed ILs due to its bigger size, compared to the common conventional IL anion and high electron-withdrawing nitrile group leads to an overall stabilization anion that may stabilize the metal nanoparticles. Stable and better separated iron and silver nanoparticles are obtained by the decomposition of corresponding Fe2(CO)9 and AgPF6, respectively, under N2-atmosphere in newly designed nitrile functionalized 4,5-dicyanoimidazolate anion based IL. Very small and uniform size for Fe-nanoparticles of about 1.8 ± 0.6 nm were achieved without any additional stabilizers or capping molecules. Comparatively bigger size of Ag-nanoparticles was obtained through the reduction of AgPF6 by hydrogen gas. Additionally, the AgPF6 precursor was decomposed under microwave irradiation (MWI), fabricating nut-in-shell-like, that is, core-separated-from-shell Ag-nano-structures. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 220 Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-89696 SP - 5476 EP - 5483 ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Thomas, Arne A1 - Holdt, Hans-Jürgen T1 - In situ synthesis of amide-imidate-imidazolate ligand and formation of metal-organic frameworks: Application for gas storage JF - Microporous and mesoporous materials : zeolites, clays, carbons and related materials N2 - In this review article, we highlight the synthesis, structures and gas-sorption properties of a series of nine isostructural IFPs (IFP = Imidazolate Framework Potsdam) and two H-bonded networks. IFPs were synthesized by in situ partial hydrolysis of a 4,5-dicyanoimidazole under solvothermal conditions and hence an imidazolate-4-amide-5-imidate linker (C5H3N4O2) was generated, forming the metal -amide-imidate-imidazolateframeworks [M(C5H3N4O2)-R]. Varying R in the 2-substitued linker (R = Me, Cl, Br, Et, OMe and OEt) and metal centre (M2+ = zinc and cobalt) allowed the variation in channel diameter (4.2-03 angstrom) and a fine-tuning of the polarity and functionality of the channel walls of IFPs. Furthermore, we show that using ethyl or alkoxy substituted IFPs the flexible groups act as molecular gates for guest molecules. This allows highly selective CO2 sorption over Ny and CH4 gases. Moreover, during the synthesis of methoxy substituted IFPs (IFP-7 and -8), an imidazolate-4,5-diamide-2-olate linker (C5H4N4O3) formed in situ leads to the formation of a molecular building block (MBB) with a M-6 octahedron inscribed in a M-8 cube (M Zn2+ and Co2+). The MBBs connect by amide amide hydrogen bonds to a 3D robust supramolecular networks [Zn-14(C5H4N4O3)(12)(O) (OH)(2) (DMF)(4) denoted as 1 and 2, respectively, DMF = N,N'-dimethylformamide], which can be activated for N-2, CO2, CH4, and H-2 gas-sorption. (C) 2015 Elsevier Inc. All rights reserved. KW - Flexible linker KW - Gas sorption KW - Gate-effects KW - Hydrogen-bonding KW - Solvothermal synthesis Y1 - 2015 U6 - https://doi.org/10.1016/j.micromeso.2015.01.049 SN - 1387-1811 SN - 1873-3093 VL - 216 SP - 2 EP - 12 PB - Elsevier CY - Amsterdam ER -