@article{AstSchwarzeMuelleretal.2013, author = {Ast, Sandra and Schwarze, Thomas and M{\"u}ller, Holger and Sukhanov, Aleksey and Michaelis, Stefanie and Wegener, Joachim and Wolfbeis, Otto S. and K{\"o}rzd{\"o}rfer, Thomas and D{\"u}rkop, Axel and Holdt, Hans-J{\"u}rgen}, title = {A highly K+-Selective Phenylaza-[18]crown-6-Lariat-Ether-Based Fluoroionophore and its application in the sensing of K+ Ions with an optical sensor film and in cells}, series = {Chemistry - a European journal}, volume = {19}, journal = {Chemistry - a European journal}, number = {44}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0947-6539}, doi = {10.1002/chem.201302350}, pages = {14911 -- 14917}, year = {2013}, abstract = {Herein, we report the synthesis of two phenylaza-[18]crown-6 lariat ethers with a coumarin fluorophore (1 and 2) and we reveal that compound 1 is an excellent probe for K+ ions under simulated physiological conditions. The presence of a 2-methoxyethoxy lariat group at the ortho position of the anilino moiety is crucial to the substantially increased stability of compounds 1 and 2 over their lariat-free phenylaza-[18] crown-6 ether analogues. Probe 1 shows a high K+/Na+ selectivity and a 2.5-fold fluorescence enhancement was observed in the presence of 100 mm K+ ions. A fluorescent membrane sensor, which was prepared by incorporating probe 1 into a hydrogel, showed a fully reversible response, a response time of 150 s, and a signal change of 7.8\% per 1 mm K+ within the range 1-10 mm K+. The membrane was easily fabricated (only a single sensing layer on a solid polyester support), yet no leaching was observed. Moreover, compound 1 rapidly permeated into cells, was cytocompatible, and was suitable for the fluorescent imaging of K+ ions on both the extracellular and intracellular levels.}, language = {en} } @article{SchwarzeTraegerKellingetal.2013, author = {Schwarze, Thomas and Traeger, Juliane and Kelling, Alexandra and Schilde, Uwe and Holdt, Hans-J{\"u}rgen}, title = {Macrocyclic dithiomaleonitriles for an efficient PdCl2 coordination}, series = {Inorganica chimica acta : the international inorganic chemistry journal}, volume = {408}, journal = {Inorganica chimica acta : the international inorganic chemistry journal}, number = {2}, publisher = {Elsevier}, address = {Lausanne}, issn = {0020-1693}, doi = {10.1016/j.ica.2013.08.020}, pages = {53 -- 58}, year = {2013}, abstract = {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.}, language = {en} }