One- and two-photon spectra of platinum acetylide chromophores: a TDDFT study.

We report one- (OPA) and two-photon absorption (TPA) excitation energies and cross-sections for a series of platinum acetylides using time-dependent density functional theory. Because of the facile rotations of the trimethylphosphinyl and phenylene groups, we apply a Boltzmann-weighted average over thermally accessible conformations to obtain the final spectra, resulting in better agreement with experimental observations. We examine various basis sets and functionals to evaluate their performance in the gas-phase and in solution. Effects of donor and acceptor groups on the OPA and TPA resonances and intensities are also discussed.