Light-Induced Size-Growth of Atomically Precise Nanoclusters.

A photo-induced transformation from [Au23(S-c-C6)16]-(TOA)+ to Au28(S-c-C6)20 nanocluster was first reported in this work. The [Au23(S-c-C6)16]-(TOA)+ nanocluster is first excited to [Au23(S-c-C6)16]•-(TOA)+ by photons with energy higher than its Eg (Eg = HOMO - LUMO energy gap), and then, the negatively charged [Au23(S-c-C6)16]•- nanocluster was oxidized to the neutral state by transfering one electron to O2. The unstable neutral cluster [Au23(S-c-C6)16]0 obtained was decomposed into smaller nanocluster and finally reassembled into the Au28(S-c-C6)20 nanocluster. Time-dependent UV-vis, matrix-assisted laser desorption/ionization time of flight mass spectrometry, electron paramagnetic resonance, and electrospray ionization mass spectrometry characterizations were performed to monitor the nanocluster size transformation.