The NBO pattern in luminescent chromophores: unravelling excited-state features using TD-DFT

The optical properties of a series of recently synthesized [Chem. Eur. J., 2013, DOI: 10.1002/chem.201203625] fluorescent borate complexes based on the 2-(2'-hydroxyphenyl)benzoxazole (HBO) core have been modeled using Time-Dependent Density Functional Theory. The computations use a range-separated hybrid functional (omega B97X-D) and include vertical, adiabatic and vibronic simulations, as well as analysis of the charge-transfer characteristics of each state. This work allows us to interpret the major experimental features, including unexpected evolution of the lambda(max), band shapes and protonation effects. Two dyads, one including a BODIPY core, have also been tackled.