Zinc(II)‐Selective Ratiometric Fluorescent Sensors Based on Inhibition of Excited‐State Intramolecular Proton Transfer

Authors:
Publisher website
Google Scholar
Abstract
To develop a zinc(II)‐selective emission ratiometric probe suitable for biological applications, we explored the cation‐induced inhibition of excited‐state intramolecular proton transfer (ESIPT) with a series of 2‐(2′‐benzenesulfonamidophenyl)benzimidazole derivatives. In the absence of ZnII at neutral pH, the fluorophores undergo ESIPT to yield a highly Stokes' shifted emission from the proton‐transfer tautomer. Coordination of ZnII inhibits the ESIPT process and yields a significant hypsochromic shift of the fluorescence emission maximum. Whereas the paramagnetic metal cations CuII, FeII, NiII, CoII, and MnII result in fluorescence quenching, the emission response is not altered by millimolar concentrations of CaII or MgII, rendering the sensors selective for ZnII among all biologically important metal cations. Due to the modular architecture of the fluorophore, the ZnII binding affinity can be readily tuned by implementing simple structural modifications. The synthesized probes are suitable to gauge free ZnII concentrations in the micromolar to picomolar range under physiological conditions.

This publication has 45 references indexed in Scilit: