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  - Schwarze, Thomas
A1  - Garz, Andreas
A1  - Teuchner, Klaus
A1  - Menzel, Ralf
A1  - Holdt, Hans-Jürgen
T1  - Two-photon probes for metal ions based on phenylaza[18]crown-6 ethers and 1,2,3-triazoles as pi-linkers
JF  - ChemPhysChem : a European journal of chemical physics and physical chemistry
KW  - absorption
KW  - cations
KW  - click chemistry
KW  - dyes/pigments
KW  - fluorescence
Y1  - 2014
U6  - https://doi.org/10.1002/cphc.201402232
SN  - 1439-4235
SN  - 1439-7641
VL  - 15
IS  - 12
SP  - 2436
EP  - 2439
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Ast, Sandra
A1  - Fischer, Tobias
A1  - Müller, Holger
A1  - Mickler, Wulfhard
A1  - Schwichtenberg, Mathias
A1  - Rurack, Knut
A1  - Holdt, Hans-Jürgen
T1  - Integration of the 1,2,3-Triazole "Click" Motif as a potent signalling element in metal ion responsive fluorescent probes
JF  - Chemistry - a European journal
N2  - 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.
KW  - charge transfer
KW  - click chemistry
KW  - electron transfer
KW  - fluorescent probes
KW  - metal ions
Y1  - 2013
U6  - https://doi.org/10.1002/chem.201201575
SN  - 0947-6539
VL  - 19
IS  - 9
SP  - 2990
EP  - 3005
PB  - Wiley-VCH
CY  - Weinheim
ER  -