Facile one-pot synthesis of luminescent-thiolated Au nanocluster and Au(I)–thiolate complexes as highly selective Cu²⁺ probes

Here in this paper, we reported of a facile photo-induced one-step method for synthesizing highly luminescent Au(I)–thiolate complexes (size ~2–3 nm) and thiolated Au nanocluster (AuNC, size ~1.6 nm). The hydrophilic thiol being 3-mercaptopropanoic acid (3-MPA) was used as stabilizing agent. The as-prepared Au(I)–thiolate complexes exhibit bright red photoluminescence (PL) and were used as an efficient sensor for the selective detection of Cu²⁺ ions. We also observed the formation of thiol-stabilized Au nanoparticles through continuous electron beam irradiation of Au(I)–thiolated complexes. The Au(I)–thiolate complexes show a PL lifetime on the μs time scale, whereas the PL lifetime of the thiolated AuNC is on the ns time scales. The photo-physical, electronic, structural and morphological properties of the thiolated AuNC and Au(I)–thiolate complexes were examined upon performing UV–Vis absorption spectroscopy, stationary and time-resolved PL spectroscopy, X-ray photoelectron spectroscopy, femtosecond transient absorption spectroscopy and transmission electron microscopy experiments.