@article{BalischewskiBehrensZehbeetal.2020,
  author    = {Balischewski, Christian and Behrens, Karsten and Zehbe, Kerstin and G{\"u}nter, Christina and Mies, Stefan and Sperlich, Eric and Kelling, Alexandra and Taubert, Andreas},
  title     = {Ionic liquids with more than one metal},
  series = {Chemistry - a European journal},
  volume    = {26},
  journal   = {Chemistry - a European journal},
  number    = {72},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {0947-6539},
  doi       = {10.1002/chem.202003097},
  pages     = {17504 -- 17513},
  year      = {2020},
  abstract  = {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.},
  language  = {en}
}
@article{BalischewskiBhattacharyyaSperlichetal.2022,
  author    = {Balischewski, Christian and Bhattacharyya, Biswajit and Sperlich, Eric and G{\"u}nter, Christina and Beqiraj, Alkit and Klamroth, Tillmann and Behrens, Karsten and Mies, Stefan and Kelling, Alexandra and Lubahn, Susanne and Holtzheimer, Lea and Nitschke, Anne and Taubert, Andreas},
  title     = {Tetrahalidometallate(II) ionic liquids with more than one metal},
  series = {Chemistry - a European journal},
  volume    = {28},
  journal   = {Chemistry - a European journal},
  number    = {64},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1521-3765},
  doi       = {10.1002/chem.202201068},
  pages     = {13},
  year      = {2022},
  abstract  = {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.},
  language  = {en}
}
@misc{BehrensBalischewskiSperlichetal.2022,
  author    = {Behrens, Karsten and Balischewski, Christian and Sperlich, Eric and Menski, Antonia Isabell and Balderas-Valadez, Ruth Fabiola and Pacholski, Claudia and G{\"u}nter, Christina and Lubahn, Susanne and Kelling, Alexandra and Taubert, Andreas},
  title     = {Mixed chloridometallate(ii) ionic liquids with tunable color and optical response for potential ammonia sensors},
  series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {1316},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-58751},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-587512},
  pages     = {35072 -- 35082},
  year      = {2022},
  abstract  = {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.},
  language  = {en}
}
@article{BehrensBalischewskiSperlichetal.2022,
  author    = {Behrens, Karsten and Balischewski, Christian and Sperlich, Eric and Menski, Antonia Isabell and Balderas-Valadez, Ruth Fabiola and Pacholski, Claudia and G{\"u}nter, Christina and Lubahn, Susanne and Kelling, Alexandra and Taubert, Andreas},
  title     = {Mixed chloridometallate(ii) ionic liquids with tunable color and optical response for potential ammonia sensors},
  series = {RSC Advances},
  volume    = {12},
  journal   = {RSC Advances},
  publisher = {RSC},
  address   = {London},
  issn      = {2046-2069},
  doi       = {10.1039/d2ra05581c},
  pages     = {35072 -- 35082},
  year      = {2022},
  abstract  = {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.},
  language  = {en}
}
@misc{BhattacharyyaBalischewskiSperlichetal.2023,
  author    = {Bhattacharyya, Biswajit and Balischewski, Christian and Sperlich, Eric and G{\"u}nter, Christina and Mies, Stefan and Kelling, Alexandra and Taubert, Andreas},
  title     = {N-Butyl Pyridinium Diiodido Argentate(I)},
  series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {1341},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-60487},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-604874},
  pages     = {7},
  year      = {2023},
  abstract  = {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.},
  language  = {en}
}
@article{BhattacharyyaBalischewskiSperlichetal.2023,
  author    = {Bhattacharyya, Biswajit and Balischewski, Christian and Sperlich, Eric and G{\"u}nter, Christina and Mies, Stefan and Kelling, Alexandra and Taubert, Andreas},
  title     = {N-Butyl Pyridinium Diiodido Argentate(I)},
  series = {Advanced materials interfaces},
  volume    = {10},
  journal   = {Advanced materials interfaces},
  number    = {12},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {2196-7350},
  doi       = {10.1002/admi.202202363},
  pages     = {7},
  year      = {2023},
  abstract  = {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.},
  language  = {en}
}
@article{FudickarMetzMaiLindeetal.2021,
  author    = {Fudickar, Werner and Metz, Melanie and Mai-Linde, Yasemin and Kr{\"u}ger, Tobias and Kelling, Alexandra and Sperlich, Eric and Linker, Torsten},
  title     = {Influence of functional groups on the ene reaction of singlet oxygen with 1,4-cyclohexadienes},
  series = {Photochemistry and photobiology : the official journal of the American Society for Photobiology},
  volume    = {97},
  journal   = {Photochemistry and photobiology : the official journal of the American Society for Photobiology},
  number    = {6},
  publisher = {Wiley},
  address   = {Malden, Mass.},
  issn      = {0031-8655},
  doi       = {10.1111/php.13422},
  pages     = {1289 -- 1297},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@article{KrauseSperlichSchmidt2021,
  author    = {Krause, Andreas and Sperlich, Eric and Schmidt, Bernd},
  title     = {Matsuda-Heck arylation of itaconates},
  series = {Organic \& biomolecular chemistry : an international journal of synthetic, physical and biomolecular organic chemistry},
  volume    = {19},
  journal   = {Organic \& biomolecular chemistry : an international journal of synthetic, physical and biomolecular organic chemistry},
  number    = {19},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1477-0520},
  doi       = {10.1039/d1ob00392e},
  pages     = {4292 -- 4302},
  year      = {2021},
  abstract  = {Itaconic acid esters and hemiesters undergo Pd-catalyzed coupling reactions with arene diazonium salts in high to excellent yields. The coupling products of ortho-nitro arene diazonium salts can be converted in one or two steps to benzazepine-2-ones.},
  language  = {en}
}
@article{KruegerBramborgKellingetal.2021,
  author    = {Kr{\"u}ger, Tobias and Bramborg, Andrea and Kelling, Alexandra and Sperlich, Eric and Linker, Torsten},
  title     = {Birch Reduction of Arenes as an Easy Entry to γ-Spirolactones},
  series = {European journal of organic chemistry},
  volume    = {2021},
  journal   = {European journal of organic chemistry},
  number    = {46},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1434-193X},
  doi       = {10.1002/ejoc.202101018},
  pages     = {6383 -- 6391},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@article{KwesigaKellingKerstingetal.2020,
  author    = {Kwesiga, George and Kelling, Alexandra and Kersting, Sebastian and Sperlich, Eric and von Nickisch-Rosenegk, Markus and Schmidt, Bernd},
  title     = {Total syntheses of prenylated isoflavones from Erythrina sacleuxii and their antibacterial activity},
  series = {Journal of natural products},
  volume    = {83},
  journal   = {Journal of natural products},
  number    = {11},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0163-3864},
  doi       = {10.1021/acs.jnatprod.0c00932},
  pages     = {3445 -- 3453},
  year      = {2020},
  abstract  = {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.},
  language  = {en}
}