title: Modulation of iridium(III) phosphorescence via photochromic ligands: a density functional theory study.
abstract: The photochromic iridium(iii) complex (Py-BTE)(2)Ir(acac) synthesized by Tan et al. [W. Tan et al., Org. Lett. 2009, 11, 161-164] has shown distinct photo-reactivity and photo-controllable phosphorescence. We here present a density functional theory study on the (Py-BTE)(2)Ir(acac) complex to explore the mechanism at the molecular level and to help further design of photochromic iridium(iii) complexes with the desirable properties. The hybrid functional PBE0, with 25% Hartree-Fock exchange, is found to give an optimal structure compared with X-ray crystallographic data. The absorption bands are well reproduced by using time-dependent density functional theory calculations, lending the possibility to assign the metal-to-ligand and intra-ligand charge transfer transitions. The radiative and nonradiative deactivation rate constants, k(r) and k(nr), are rationalized for both the open-ring and closed-ring forms of the complex. The very large k(nr) and small k(r) make the closed-ring form of the complex non-emissive. The triplet reactivity of the Py-BTE ligand is also studied by performing density functional theory calculations on the potential energy surfaces of the ground state and the lowest triplet state.
authors.affiliation: Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237, People's Republic of China.
authors.forename: Xin
authors.initials: X
authors.lastname: Li
authors.forename: Qiong
authors.initials: Q
authors.lastname: Zhang
authors.forename: Yaoquan
authors.initials: Y
authors.lastname: Tu
authors.forename: Hans
authors.initials: H
authors.lastname: Agren
authors.forename: He
authors.initials: H
authors.lastname: Tian
mesh_terms: D056831:Coordination Complexes / Q000737:chemistry; D007495:Iridium / Q000737:chemistry*; D007700:Kinetics; D008024:Ligands; D049449:Luminescence
chemical_list: D056831:Coordination Complexes; D008024:Ligands; D007495:Iridium