Light-induced switching of azo-imidazoles on gold nanoparticles

In the past decade, a large number of photochromic compounds with different photoresponsive units have been synthesized and their properties have been investigated [1,2]. Recently photochromic compounds have attracted considerable attention due to their extensive applications in display and anti-counterfeiting systems, optical storage and memory devices, and optical molecular switches. The self-assembly of functional photochromic molecules as ligands on the surface of metal nanoparticles is a promising strategy for the fabrication of nanoscale devices with potential applications in clinical diagnostics, optical storage and photoswitchable surface wettability [3].In the present study, gold nanoparticles (AuNPs) were immobilized with sulfurmodified photochromic azo-imidazole derivatives and their photochromic performance was studied. In this class of photochromic compounds, a reversible switching reaction occurred between the trans-enol photoisomer into cis-keto and/or quinone-hydrazone photoisomers and vice versa under UV irradiation