TD-DFT Studies of Electronic Structures in Cyclometalated Phenylpyrazol Ir(III) Complexes: Fac-Ir(ppz) 3 and Ir(ppz) 2(acac)

Abstract

The ground state and low-lying excited electronic states of two related Ir(III)complexes fac-Ir(ppz)3(1)and Ir(ppz)2(acac)(2)are studied using density functional theory where ppz = phenylpyrazol, acac = acetylacetonate and fac = facial. The complex 1 is a blue phosphorescent material with about 450 nm of electroluminescent peak. The ground states of these complexes are studied using Becke's three parameter hybrid functional with Perdew 86(B3LYP)and the structure analysis of the optimized geometries are processed. Excited triplet and singlet states are examined using time-dependent density functional theory. Every low-lying transition for the former molecule and 6 lowest singlet and triplet excitations for the latter molecule are categorized as metal-to-ligand charge-transfer transitions, because the metal orbitals involved in the transitions have significant admixture of ligandπcharacter with amount of metal 5d character in the occupied molecular orbitals related to those transitions. Through the comparison of the calculated excitons with experimental absorption spectra, each peak was examined its originality.