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 approximate to 270 times lower than the maximum contamination level (2.7 M) 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 CN- can be observed.