Theoretical Studies on Phosphorescent Materials: The Conjugation-Extended Pt-II Complexes

摘要

A theoretical study on the Pt-II complex A based on a dimesitylboron (BMes(2))-functionalized [Pt(C<^>N)(acac)] (C<^>N=2-phenyl-pyridyl, acac=acetylaceton) complex, as well as three conjugation-extended analogues of the methylimidazole (C*) ligand BMes(2)-[Pt(C<^>C*)(acac)] complexes B-D is performed. Their theoretical geometries, electronic structures, emission properties, and the radiative decay rate constants (k(r)) were also investigated. The energy differences between the two highest occupied orbitals with dominant Pt d-orbital components (dd(occ)) of D both at the ground and excited states are the smallest of all. Compared with B, the charge transfer in D possesses a marked trend towards the extended conjugated group, while C changed inconspicuously. The lowest-lying absorptions and the phosphorescence of them can be described as a mixed metal-to-ligand charge transfer (MLCT)/intra-ligand * charge transfer (ILCT) and (MLCT)-M-3/(ILCT)-I-3, respectively. The variation of charge transfer properties induced by extended conjugation and the radiative decay rate constants (k(r)) calculated revealed that D is a more efficient blue phosphorescence material with a 497nm emission transition.