Preparation and use of Cu nanoclusters as fluorescent probes to determine Au(III) ions

Polyethyleneimine-capped Cu nanoclusters (PEI-CuNCs) with a mean diameter of 2.5   nm and that emitted blue light at 485   nm were synthesized. The fluorescence of PEI-CuNCs was strongly quenched when Au(III) ions were present. Because of this specific response, a PEI-CuNC-based fluorescent turn-off sensor was developed. Under optimum conditions, a good linear relationship (R 2 =0.993) was found between the relative fluorescence intensity ( F 0 / F ) and the Au(III) ion concentration between 0.5 and 15   µM. The detection limit for Au(III) ions was 0.06   µM. The quenching mechanism was assessed by performing X-ray photoelectron spectroscopy spectra studies. The fluorescence quenching was ascribed to photo-induced electron transfer from the PEI-CuNCs to the AuCl 4 − occur. Using The method described is a new way of quantifying Au(III) ions.