Aggregation induced emission of amino-thiol capped gold nanoparticles (GNPs) through metal-amino-coordination.

Au11(SG)7 gold nanoparticles (GNPs) were synthesized from HAuCl4 using thiol compounds containing an amino group to serve as both the reducing agent and the ligand. A three-dimensional network structure (…Au-SNH2→Mn+⟵H2NS-Au…) was formed after the Mn+ (Pb2+, Cd2+, Zn2+ and Ag+) coordinated the gold nanoparticles through the amino group in the thiol ligand, which promoted aurophilicity (…Au…Au…) and induced GNP aggregation and emission. The differences in coordination between the amino group and metal ions resulted in different emission wavelengths (Pb2+, Cd2+, Zn2+ and Ag+: λex = 365 nm˜370 nm, λem = 580, 645, 630 and 565 nm). Aggregation induced emission of amino thiol capped GNPs via coordination of Pb2+ or Cd2+ can be used as a fluorescent sensor of the both metal ions (λex = 365 nm, λem = 580/645 nm) and were used for living bioimaging in vivo and in vitro.