Polyethyleneimine Solubilized Luminescent Au(I)-Thiolate Complexes for Highly Sensitive and Selective Cyanide Anion Sensing

Cyanide (CN−) is a highly toxic anion to human beings, exploring efficient probes for sensitive and selective detection of it is very important. In this study, we explore a simple one-pot reaction to synthesize polyethyleneimine (PEI) solubilized Au(I)-MUA (11-mercaptoundecanoic acid) complexes under mild condition. The as prepared Au(I)-MUA complexes exhibit strong red photoluminescence (PL) and can act as sensitive and selective CN− optical sensor in aqueous media based on the chemical reaction between CN− and gold atom that quench the fluorescence, and the limit of detection is 10 nM, which is ∼270 times lower than the maximum contamination level (2.7 μM) in drinking water permitted by WHO. Additionally, real water sample from a local lake is tested with these optical sensors, and the PL variation caused by 0.1 μ CN− can be observed.