Journal of Chemical Sciences | 2021
Selective sensing of thiols by aryl iodide stabilized fluorescent gold cluster through turn-off excimer emission caused by ligand displacement
Abstract
Here we report fluorescence quenching based detection of selected “Thiol” molecules by employing a luminescent gold cluster through ligand displacement strategy. First, an aryl iodide (2-Iodonaphthalene, NP) and polyvinylpyrrolidone (PVP) mixed ligand stabilized gold cluster was synthesized with a strong fluorescence signal originated from excimer of 2-Iodonaphthalene ligands grafted on gold nano surface. Among different small molecule-based ligands, thiol (R-SH) forms a strong bond with gold nanoparticles. Anticipating this property, we have found that displacement of 2-Iodonaphthalene ligand from gold nanoparticle surface by thiols results in the sensitive detection of thiols through the quenching of emission of gold cluster. The selectivity for detection of different tested analytes follows the order: GSH > Cys > hCy whereas, other non-thiol based amino acids and common salts are innocent towards fluorescence response. Easy synthesis of the fluorescent gold cluster, selective sensing of small thiol molecules, high Stern-Volmer constant (KSV=3.3×106 M-1) and ultralow detection limit (LOD of 35 nM) are notable features of the present report. A fluorescence turn-off chemosensor has been developed for sensing selected ‘thiol’ molecules by employing 2-Iodonaphthalene and polyvinylpyrrolidone (PVP) mixed ligand stabilized luminescent gold cluster through ligand displacement strategy.