title: Aggregation effect on the luminescence properties of phenylbipyridine Pt(II) acetylide complexes. A theoretical prediction with experimental evidence.
abstract: We report a combined theoretical and experimental study of both the structural and optical properties of phosphorescent cyclometalated square-planar (phenylbipyridyl)platinum(II) acetylide complexes, namely (Pt(tBu2-ĈN̂N)(C≡C-Ph)] and (Pt(hex2-ĈN̂N)(C≡C-thienyl)] that exhibit, at high concentrations, an additional emission band at longer wavelength. The geometry optimizations of both the ground and the lowest triplet excited states of the considered monomers and different possible dimers have been performed in solution using several density functional theory (DFT) functionals corrected for dispersion effects. For the dimers, which are shown to exhibit a head-to-tail configuration, a significant shortening of the Pt···Pt distance, compared to that in the ground state, is observed in the first triplet state. Moreover, we show that trimeric species are highly improbable in solution. The UV-visible absorption spectra of the complexes are well rationalized using a vertical time-dependent DFT (TD-DFT) protocol relying on a global hybrid exchange-correlation functional. Finally, the new emission band at high concentration of the complexes can be assigned to a metal-metal to ligand charge transfer excited state ((3)MMLCT).
authors: UMR 6226 CNRS-Université de Rennes 1, Campus de Beaulieu, Institut des Sciences Chimiques de Rennes , 35042 Rennes, France.
authors: Anissa
authors: A
authors: Amar
authors: Hacène
authors: H
authors: Meghezzi
authors: Julien
authors: J
authors: Boixel
authors: Hubert
authors: H
authors: Le Bozec
authors: Véronique
authors: V
authors: Guerchais
authors: Denis
authors: D
authors: Jacquemin
authors: Abdou
authors: A
authors: Boucekkine