A photoresponsive Au25 nanocluster protected by azobenzene derivative thiolates.

An Au(25) cluster protected by azobenzene derivative thiolates (S-Az) ([Au(25)(S-Az)(18)](-)) was synthesized with the aim of producing a photoresponsive Au(25) cluster. The matrix-assisted laser desorption/ionization mass spectrum of the product revealed that [Au(25)(S-Az)(18)](-) was synthesized in high purity. Optical absorption spectra of [Au(25)(S-Az)(18)](-) obtained before and after photoirradiation suggest that the azobenzenes in the ligands of Au(25)(S-Az)(18) isomerize with an efficiency of nearly 100%, both from the trans to cis conformation and from the cis to trans conformation.

Continuous modulation of electronic structure of stable thiolate-protected Au25 cluster by Ag doping.

The effect of Ag doping on the electronic structure of a stable thiolate-protected Au(25) cluster (Au(25)(SR)(18)) was studied by measuring the optical spectra of Au(25-n)Ag(n)(SC(12)H(25))(18) (n = 0-11) and the results reveal that the electronic structure of Au(25)(SC(12)H(25))(18) is sensitive to Ag doping and is continuously modulated by incorporation of Ag atoms.