TY  - JOUR
A1  - Schwarze, Thomas
A1  - Schneider, Radu
A1  - Riemer, Janine
A1  - Holdt, Hans-Jürgen
T1  - A Highly K+-Selective Fluorescent Probe - Tuning the K+-Complex Stability and the K+/Na+ Selectivity by Varying the Lariat-Alkoxy Unit of a Phenylaza[18]crown-6 Ionophore
JF  - Chemistry : an Asian journal ; an ACES journal
N2  - A desirable goal is to synthesize easily accessible and highly K+/Na+-selective fluoroionophores to monitor physiological K+ levels in vitro and in vivo. Therefore, highly K+/Na+-selective ionophores have to be developed. Herein, we obtained in a sequence of only four synthetic steps a set of K+-responsive fluorescent probes 4, 5 and 6. In a systematic study, we investigated the influence of the alkoxy substitution in ortho position of the aniline moiety in -conjugated aniline-1,2,3-triazole-coumarin-fluoroionophores 4, 5 and 6 [R=MeO (4), EtO (5) and iPrO (6)] towards the K+-complex stability and K+/Na+ selectivity. The highest K+-complex stability showed fluoroionophore 4 with a dissociation constant K-d of 19mm, but the K-d value increases to 31mm in combined K+/Na+ solutions, indicating a poor K+/Na+ selectivity. By contrast, 6 showed even in the presence of competitive Na+ ions equal K-d values (K-d(K+)=45mm and K-d(K+/Na+)=45mm) and equal K+-induced fluorescence enhancement factors (FEFs=2.3). Thus, the fluorescent probe 6 showed an outstanding K+/Na+ selectivity and is a suitable fluorescent tool to measure physiological K+ levels in the range of 10-80mm in vitro. Further, the isopropoxy-substituted N-phenylaza[18]crown-6 ionophore in 6 is a highly K+-selective building block with a feasible synthetic route.
KW  - crown compounds
KW  - fluorescence
KW  - fluorescent probes
KW  - potassium
KW  - sodium
Y1  - 2016
U6  - https://doi.org/10.1002/asia.201500956
SN  - 1861-4728
SN  - 1861-471X
VL  - 11
SP  - 241
EP  - 247
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Wong, Joseph K. -H.
A1  - Ast, Sandra
A1  - Yu, Mingfeng
A1  - Flehr, Roman
A1  - Counsell, Andrew J.
A1  - Turner, Peter
A1  - Crisologo, Patrick
A1  - Todd, Matthew H.
A1  - Rutledge, Peter J.
T1  - Synthesis and Evaluation of 1,8-Disubstituted-Cyclam/Naphthalimide Conjugates as Probes for Metal Ions
JF  - ChemistryOpen : including thesis treasury
N2  - Fluorescent molecular probes for metal ions have a raft of potential applications in chemistry and biomedicine. We report the synthesis and photophysical characterisation of 1,8-disubstituted-cyclam/naphthalimide conjugates and their zinc complexes. An efficient synthesis of 1,8-bis-(2-azidoethyl)cyclam has been developed and used to prepare 1,8-disubstituted triazolyl-cyclam systems, in which the pendant group is connected to triazole C4. UV/Vis and fluorescence emission spectra, zinc binding experiments, fluorescence quantum yield and lifetime measurements and pH titrations of the resultant bis-naphthalimide ligand elucidate a complex pattern of photophysical behaviour. Important differences arise from the inclusion of two fluorophores in the one probe and from the variation of triazole substitution pattern (dye at C4 vs. N1). Introducing a second fluorophore greatly extends fluorescence lifetimes, whereas the altered substitution pattern at the cyclam amines exerts a major influence on fluorescence output and metal binding. Crystal structures of two key zinc complexes evidence variations in triazole coordination that mirror the solution-phase behaviour of these systems.
KW  - chromophores
KW  - click triazoles
KW  - fluorescent probes
KW  - macrocyclic compounds
KW  - photophysics
Y1  - 2016
U6  - https://doi.org/10.1002/open.201600010
SN  - 2191-1363
VL  - 5
SP  - 375
EP  - 385
PB  - Wiley-VCH
CY  - Weinheim
ER  -