取代基对过渡金属铱配合物结构和光谱性质的影响

采用DFT和TD-DFT方法研究了一系列(C^N)2Ir(N^N-X) C^N=2-苯基吡啶，N^N=2-吡啶基-1,3,4-恶二唑，X=氯苯(1)、X=苯基(2)、X=苯乙炔(3)和X=吡啶(4)]配合物的结构和光谱特征。首先采用B3LYP/LanL2DZ泛函优化了配合物1-4的基态几何结构，在此基础上选用UB3LYP/LanL2DZ泛函得到其激发态结构。计算得到的Ir-N(1)和Ir-N(3)基态键长和相应实验值符合得较好。在TD-DFT和PCM计算水平下，得到1-4的低能吸收和发射分别出现在454(1)、446(2)、453(3)、461(4) nm和649(1)、650(2)、642 (3)、638(4) nm。这些激发的起始分子轨道HOMO-1主要由苯基吡啶配体(C^N)占据，而终止轨道LUMOs均为*(N^N)型轨道，因此，该跃迁被指认为π-π*跃迁，具有配体到配体的电荷转移跃迁(LLCT)特征。研究显示出此类配合物的吸收和发射主要由双齿配体本身控制，受X取代群组影响较小。

The Effect of Substitutes Group on the Electron Structures and Spectroscopic Properties of Transition Metal Iridium Complexes

The structures and spectroscopic properties of a series of (C^N)2Ir(N^N-X) C^N=2-phenylpyridine, N^N = 2-pyridyl-1,3,4-oxadiazole, X=chlorobenzene (1), X=phenyl(2), X=phenylyne (3), X=pyridine (4)] complexes were investigated by the DFT and TDDFT methods. We first optimized geometrical structures in ground state of complexes 1-4, at the B3LYP/LanL2DZ levels, and the excited state structures by selected UB3LYP/LanL2DZ functionals. The calculated bond lengths of Ir-N(1) and Ir-N(3) in the ground state agree well with the corresponding experimental results. At the TD-DFT and PCM levels, 1-4 give rise to lower energy absorptions at 454(1), 446(2), 453(3), 461(4) nm and corresponding phosphorescent emissions at 649(1), 650(2), 642 (3), and 638(4) nm, respectively. The HOMO-1 of 1-4 are mainly localized on the phenylpyridine(C^N) ligands, while the LUMOs are the *(N^N) type orbital. Therefore, the transitions of 1-4 were assigned to the π-π* transition with ligand-to-ligand charge transfers(LLCT) characters. It is shown that the absorptions and emissions are significantly dominated by the bidentate ligand itself, but are minor impact by the X-substituent group.