Impact of Ligand Structure on Biological Activity and Photophysical Properties of NHC-Protected Au Nanoclusters.

N-heterocyclic carbene (NHC)-protected gold nanoclusters display high stability and high photoluminescence, making them well-suited for fluorescence imaging and photodynamic therapeutic applications. We report herein the synthesis of two bisNHC-protected Au nanoclusters with π-extended aromatic systems. Depending on the position of the π-extended aromatic system, changes to the structure of the ligand shell in the cluster are observed, with the ability to correlate increases in rigidity with increases in fluorescence quantum yield.

Photophysical investigation into room-temperature emission from xanthene derivatives.

The photophysical consequences of replacing the nitrogen heteroatom in phenothiazine with methylene are investigated for both solutions and crystalline solids. We analysed the excited state dynamics of four xanthene derivatives and observed an anomalous fluorescence from an energy level higher than the S state with lifetimes between 2.8 ns and 5.