@article{SchwarzeRiemerEidneretal.2015,
  author    = {Schwarze, Thomas and Riemer, Janine and Eidner, Sascha and Holdt, Hans-J{\"u}rgen},
  title     = {A Highly K+-Selective Two-Photon Fluorescent Probe},
  series = {Chemistry - a European journal},
  volume    = {21},
  journal   = {Chemistry - a European journal},
  number    = {32},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {0947-6539},
  doi       = {10.1002/chem.201501473},
  pages     = {11306 -- 11310},
  year      = {2015},
  abstract  = {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+.},
  language  = {en}
}
@article{SchwarzeGarzTeuchneretal.2014,
  author    = {Schwarze, Thomas and Garz, Andreas and Teuchner, Klaus and Menzel, Ralf and Holdt, Hans-J{\"u}rgen},
  title     = {Two-photon probes for metal ions based on phenylaza[18]crown-6 ethers and 1,2,3-triazoles as pi-linkers},
  series = {ChemPhysChem : a European journal of chemical physics and physical chemistry},
  volume    = {15},
  journal   = {ChemPhysChem : a European journal of chemical physics and physical chemistry},
  number    = {12},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1439-4235},
  doi       = {10.1002/cphc.201402232},
  pages     = {2436 -- 2439},
  year      = {2014},
  language  = {en}
}
@misc{AstFischerMuelleretal.2013,
  author    = {Ast, Sandra and Fischer, Tobias and M{\"u}ller, Holger and Mickler, Wulfhard and Schwichtenberg, Mathias and Rurack, Knut and Holdt, Hans-J{\"u}rgen},
  title     = {Integration of the 1,2,3-Triazole "Click" Motif as a potent signalling element in metal ion responsive fluorescent probes},
  series = {Chemistry - a European journal},
  volume    = {19},
  journal   = {Chemistry - a European journal},
  number    = {9},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {0947-6539},
  doi       = {10.1002/chem.201201575},
  pages     = {2990 -- 3005},
  year      = {2013},
  abstract  = {In a systematic approach we synthesized a new series of fluorescent probes incorporating donoracceptor (D-A) substituted 1,2,3-triazoles as conjugative -linkers between the alkali metal ion receptor N-phenylaza-[18]crown-6 and different fluorophoric groups with different electron-acceptor properties (4-naphthalimide, meso-phenyl-BODIPY and 9-anthracene) and investigated their performance in organic and aqueous environments (physiological conditions). In the charge-transfer (CT) type probes 1, 2 and 7, the fluorescence is almost completely quenched by intramolecular CT (ICT) processes involving charge-separated states. In the presence of Na+ and K+ ICT is interrupted, which resulted in a lighting-up of the fluorescence in acetonitrile. Among the investigated fluoroionophores, compound 7, which contains a 9-anthracenyl moiety as the electron-accepting fluorophore, is the only probe which retains light-up features in water and works as a highly K+/Na+-selective probe under simulated physiological conditions. Virtually decoupled BODIPY-based 6 and photoinduced electron transfer (PET) type probes 35, where the 10-substituted anthracen-9-yl fluorophores are connected to the 1,2,3-triazole through a methylene spacer, show strong ion-induced fluorescence enhancement in acetonitrile, but not under physiological conditions. Electrochemical studies and theoretical calculations were used to assess and support the underlying mechanisms for the new ICT and PET 1,2,3-triazole fluoroionophores.},
  language  = {en}
}