Synthesis, structure and optical data storage properties of silver nanoparticles modified with azobenzene thiols

Silver nanoparticles modified with photoresponsive azobenzene thiol ligands are prepared and the interaction between them has been investigated through photoisomerization behaviour by UV-vis spectroscopy. Upon irradiation with UV light at 365 nm, an increase of the absorbance centered at 445 nm corresponding to the n-π* transition band of cis azobenzene isomers is observed for azobenzene solution without Ag and a decrease of the absorbance centered at 445 nm is observed for azobenzene solution with Ag, showing strong interaction of azo chromophores with surface plasmons of Ag nanoparticles, in particular when the absorption bands are overlapped with each other. The enhanced light-responsivity has been confirmed by two-photon induced optical data storage experiments. An image can be recorded on the photoactive film doped with 7 wt% silver nanoparticles modified with azobenzene thiol ligands under writing power of 25 mW, but is failed to be recorded in the azobenzene film without Ag even under the same recording condition.