@article{HoldtMuellerKellingetal.2006, author = {Holdt, Hans-J{\"u}rgen and M{\"u}ller, Holger and Kelling, Alexandra and Drexler, Hans-Joachim and M{\"u}ller, Thomas and Schwarze, Thomas and Schilde, Uwe and Starke, Ines}, title = {Mercury(II) chloride and iodide complexes of dithia- and tetrathiacrown ethers}, issn = {0044-2313}, doi = {10.1002/zaac.200500281}, year = {2006}, abstract = {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}, language = {en} } @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{SchwarzeSperlichMuelleretal.2021, author = {Schwarze, Thomas and Sperlich, Eric and M{\"u}ller, Thomas and Kelling, Alexandra and Holdt, Hans-J{\"u}rgen}, title = {Synthesis efforts of acyclic bis(monoalkylamino)maleonitriles and macrocyclic bis(dialkylamino)maleonitriles as fluorescent probes for cations and a new colorimetric copper(II) chemodosimeter}, series = {Helvetica chimica acta}, volume = {104}, journal = {Helvetica chimica acta}, number = {6}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1522-2675}, doi = {10.1002/hlca.202100028}, pages = {e2100028}, year = {2021}, abstract = {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.}, language = {en} } @article{Schwarze2021, author = {Schwarze, Thomas}, title = {Determination of Pd2+ by fluorescence enhancement caused by an off-switching of an energy- and an electron transfer}, series = {ChemistrySelect}, volume = {6}, journal = {ChemistrySelect}, number = {3}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2365-6549}, doi = {10.1002/slct.202003975}, pages = {318 -- 322}, year = {2021}, abstract = {In this paper, we introduce a fluorescent dye 1, which is able to detect selectively Pd2+ by a clear fluorescence enhancement (FE) in THF. In the presence of eight Pd2+ equivalents, we observed a fluorescence enhancement factor (FEF) of 28.3. The high Pd2+ induced FEF can be explained by an off switching of multiple quenching processes within 1 by Pd2+. In the free dye 1 a photoinduced electron transfer (PET) and energy transfer (ET) takes place and quenches the anthracenic fluorescence. The coordination of eight Pd2+ units by the alkylthio-substituted porphyrazine receptor suppresses the PET and ET quenching process and the anthracenic fluorescence is switched on.}, language = {en} } @article{SchwarzeRiemer2020, author = {Schwarze, Thomas and Riemer, Janine}, title = {Highly K+ selective probes with fluorescence emission wavelengths higher than 500 nm in water}, series = {ChemistrySelect}, volume = {5}, journal = {ChemistrySelect}, number = {42}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2365-6549}, doi = {10.1002/slct.202003785}, pages = {13174 -- 13178}, year = {2020}, abstract = {Herein, we report on the synthesis of highly K+/Na+ selective fluorescent probes in a feasible number of synthetic steps. These K+ selective fluorescent probes, so called fluoroionophores, 1 and 2 consists of different highly K+/Na+ selective building blocks the alkoxy-substituted N-phenylaza-18-crown-6 lariat ethers (ionophores) and "green" (cf. coumarin unit in 1) or "red" (cf. nile red unit in 2) fluorescent moieties (fluorophores). The fluorescent probes 1 and 2 show K+ induced fluorescence enhancement factors of 4.1 for 1 and 1.9 for 2 and dissociation constants for the corresponding K+ complexes of 43 mM (1+K+) and 18 mM (2+K+) in buffered aqueous solution. The fluorescence signal of 1 and 2 is changed by less than 5 \% by pH values in the range of 6.8 to 8.8. Thus, 1 and 2 are capable fluorescent tools to determine extracellular K+ levels by fluorescence enhancements at wavelengths higher than 500 nm.}, language = {en} } @article{SchwarzeSprengerRiemer2020, author = {Schwarze, Thomas and Sprenger, Tobias and Riemer, Janine}, title = {1,2,3-Triazol-1,4-diyl-Fluoroionophores for Zn2+, Mg2+ and Ca2+ based on Fluorescence Intensity Enhancements in Water}, series = {ChemistrySelect}, volume = {5}, journal = {ChemistrySelect}, number = {41}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2365-6549}, doi = {10.1002/slct.202003695}, pages = {12727 -- 12735}, year = {2020}, abstract = {Herein, we represent cation-responsive fluorescent probes for the divalent cations Zn2+, Mg2+ and Ca2+, which show cation-induced fluorescence enhancements (FE) in water. The Zn2+-responsive probes Zn1, Zn2, Zn3 and Zn4 are based on o-aminoanisole-N,N-diacetic acid (AADA) derivatives and show in the presence of Zn2+ FE factors of 11.4, 13.9, 6.1 and 8.2, respectively. Most of all, Zn1 and Zn2 show higher Zn2+ induced FE than the regioisomeric triazole linked fluorescent probes Zn3 and Zn4, respectively. In this set, ZN2 is the most suitable probe to detect extracellular Zn2+ levels. For the Mg2+-responsive fluorescent probes Mg1, Mg2 and Mg3 based on o-aminophenol-N,N,O-triacetic acid (APTRA) derivatives, we also found that the regioisomeric linkage influences the fluorescence responds towards Mg2+ (Mg1+100 mM Mg2+ (FEF=13.2) and Mg3+100 mM Mg2+ (FEF=2.1)). Mg2 shows the highest Mg2+-induced FE by a factor of 25.7 and an appropriate K-d value of 3 mM to measure intracellular Mg2+ levels. Further, the Ca2+-responsive fluorescent probes Ca1 and Ca2 equipped with a 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) derivative show high Ca2+-induced FEs (Ca1 (FEF=22.1) and Ca2 (FEF=23.0)). Herein, only Ca1 (K-d=313 nM) is a suitable Ca2+ fluorescent indicator to determine intracellular Ca2+ levels.}, language = {en} } @misc{SchwarzeRiemerMuelleretal.2019, author = {Schwarze, Thomas and Riemer, Janine and M{\"u}ller, Holger and John, Leonard and Holdt, Hans-J{\"u}rgen and Wessig, Pablo}, title = {Na+ Selective Fluorescent Tools Based on Fluorescence Intensity Enhancements, Lifetime Changes, and on a Ratiometric Response}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1136}, issn = {1866-8372}, doi = {10.25932/publishup-43748}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-437482}, pages = {13}, year = {2019}, abstract = {Over the years, we developed highly selective fluorescent probes for K+ in water, which show K+-induced fluorescence intensity enhancements, lifetime changes, or a ratiometric behavior at two emission wavelengths (cf. Scheme 1, K1-K4). In this paper, we introduce selective fluorescent probes for Na+ in water, which also show Na+ induced signal changes, which are analyzed by diverse fluorescence techniques. Initially, we synthesized the fluorescent probes 2, 4, 5, 6 and 10 for a fluorescence analysis by intensity enhancements at one wavelength by varying the Na+ responsive ionophore unit and the fluorophore moiety to adjust different K-d values for an intra- or extracellular Na+ analysis. Thus, we found that 2, 4 and 5 are Na+ selective fluorescent tools, which are able to measure physiologically important Na+ levels at wavelengths higher than 500 nm. Secondly, we developed the fluorescent probes 7 and 8 to analyze precise Na+ levels by fluorescence lifetime changes. Herein, only 8 (K-d=106 mm) is a capable fluorescent tool to measure Na+ levels in blood samples by lifetime changes. Finally, the fluorescent probe 9 was designed to show a Na+ induced ratiometric fluorescence behavior at two emission wavelengths. As desired, 9 (K-d=78 mm) showed a ratiometric fluorescence response towards Na+ ions and is a suitable tool to measure physiologically relevant Na+ levels by the intensity change of two emission wavelengths at 404 nm and 492 nm.}, language = {en} } @article{SchwarzeMuellerSchmidtetal.2017, author = {Schwarze, Thomas and Mueller, Holger and Schmidt, Darya and Riemer, Janine and Holdt, Hans-J{\"u}rgen}, title = {Design of Na+-Selective Fluorescent Probes: A Systematic Study of the Na+-Complex Stability and the Na+/K+ Selectivity in Acetonitrile and Water}, series = {Chemistry - a European journal}, volume = {23}, journal = {Chemistry - a European journal}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0947-6539}, doi = {10.1002/chem.201605986}, pages = {7255 -- 7263}, year = {2017}, abstract = {There is a tremendous demand for highly Na+-selective fluoroionophores to monitor the top analyte Na+ in life science. Here, we report a systematic route to develop highly Na+/K+ selective fluorescent probes. Thus, we synthesized a set of fluoroionophores 1, 3, 4, 5, 8 and 9 (see Scheme 1) to investigate the Na+/K+ selectivity and Na(+-)complex stability in CH3CN and H2O. These Na+-probes bear different 15-crown-5 moieties to bind Na+ stronger than K+. In the set of the diethylaminocoumarin-substituted fluoroionophores 1-5, the following trend of fluorescence quenching 1 > 3 > 2 > 4 > 5 in CH3CN was observed. Therefore, the flexibility of the aza-15-crown-5 moieties in 1-4 determines the conjugation of the nitrogen lone pair with the aromatic ring. As a consequence, 1 showed in CH3CN the highest Na+-induced fluorescence enhancement (FE) by a factor of 46.5 and a weaker K+ induced FE of 3.7. The Na+-complex stability of 1-4 in CH3CN is enhanced in the following order of 2 > 4 > 3 > 1, assuming that the O-atom of the methoxy group in the ortho-position, as shown in 2, strengthened the Na+-complex formation. Furthermore, we found for the N( o-methoxyphenyl) aza-15-crown-5 substituted fluoroionophores 2, 8 and 9 in H2O, an enhanced Na+-complex stability in the following order 8 > 2 > 9 and an increased Na+/K+ selectivity in the reverse order 9 > 2 > 8. Notably, the Na+-induced FE of 8 (FEF = 10.9), 2 (FEF = 5.0) and 9 (FEF = 2.0) showed a similar trend associated with a decreased K+-induced FE [8 (FEF = 2.7) > 2 (FEF = 1.5) > 9 (FEF = 1.1)]. Here, the Na+-complex stability and Na+/K+ selectivity is also influenced by the fluorophore moiety. Thus, fluorescent probe 8 (K-d = 48 mm) allows high-contrast, sensitive, and selective Na+ measurements over extracellular K+ levels. A higher Na+/K+ selectivity showed fluorescent probe 9, but also a higher Kd value of 223 mm. Therefore, 9 is a suitable tool to measure Na+ concentrations up to 300 mm at a fluorescence emission of 614 nm.}, language = {en} } @article{SchwarzeMuellerAstetal.2014, author = {Schwarze, Thomas and M{\"u}ller, Holger and Ast, Sandra and Steinbr{\"u}ck, D{\"o}rte and Eidner, Sascha and Geißler, Felix and Kumke, Michael Uwe and Holdt, Hans-J{\"u}rgen}, title = {Fluorescence lifetime-based sensing of sodium by an optode}, series = {Chemical Communications}, journal = {Chemical Communications}, editor = {Kumke, Michael Uwe}, publisher = {The Royal Society Chemistry}, address = {Cambridge}, issn = {0022-4936}, pages = {14167 -- 14170}, year = {2014}, abstract = {We report a 1,2,3-triazol fluoroionophore for detecting Na+ that shows in vitro enhancement in the Na+-induced fluorescence intensity and decay time. The Na+-selective molecule 1 was incorporated into a hydrogel as a part of a fiber optical sensor. This sensor allows the direct determination of Na+ in the range of 1-10 mM by measuring reversible fluorescence decay time changes.}, language = {en} } @article{SchwarzeKellingMuelleretal.2012, author = {Schwarze, Thomas and Kelling, Alexandra and M{\"u}ller, Holger and Trautmann, Michael and Klamroth, Tillmann and Baumann, Otto and Strauch, Peter and Holdt, Hans-J{\"u}rgen}, title = {N-2-Pyridinylmethyl-N '-arylmethyl-diaminomaleonitriles: New Highly Selective Chromogenic Chemodosimeters for Copper(II)}, series = {Chemistry - a European journal}, volume = {18}, journal = {Chemistry - a European journal}, number = {34}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0947-6539}, doi = {10.1002/chem.201201731}, pages = {10506 -- 10510}, year = {2012}, language = {en} }