摘要
采用密度泛函方法从理论上研究了一类[Os(PH3)2(CN)2(N^N)][N^N=bpy(1);N^N=phbpy(2);bpy=2,2'-联吡啶;phbpy=4,4-双苯基-2,2'-联吡啶]配合物的几何结构和光谱性质。采用含时密度泛函方法中的PBE0泛函,得到两个配合物的最低能单态吸收和磷光发射分别在471(1)、487(2)nm和619(1)、661(2)nm。1和2的高能占据分子轨道主要由金属Os和CN配体占据,而低能非占据分子轨道主要受N^N配体成份控制,因此1和2的最低能吸收被指认为MLCT跃迁,并混有少量的LLCT微扰,且其强度最大的高能吸收表现为配体(联吡啶)内部的电荷转移跃迁。计算结果表明,CN和联吡啶配体在跃迁过程中担当两个独立的发色团。与分子1相比,由于2在联吡啶配体上增加了π共轭效应,导致其吸收和发射产生红移。
The geometries and spectroscopic properties of a series of Os （II） complexes [Os （ PH3 ） 2 （CN） 2 （N^N） ] [ N^N = bpy （ 1 ） ; N^N = phbpy （2） and bpy = 2,2＇- bipyridine ; phbpy = 4,4 - diphenyl - 2,2＇- bipyridine ] were investigated theoretically by density functional theory methods. The calculated lowest -lying absorptions with TDDFT method based on Perdew- Burke- Erzenrhof （PBE0） functional are at 471 （1） and 487 （2） nm and phosphorescent emissions at 619 （1） and 661 （2） nm for 1 and 2, respectively. The high -energy occupied molecular orbitals were dominantly localized on the Os atom and CN ligand, while the lowest unoccupied molecular orbitals were mainly composed of N^N ligand, therefore, the lowest - lying energy absorptions of 1 and 2 were attributed to the MLCT transition mixed with some LLCT transition characters, and the high energy absorptions were also manifested as ILCT （N^N ligand） transition characters. The calculated results showed that the CN and N^N groups act as two independent chromophores in transition processes. Compared with 1, the absorptions and emissions of 2 were red - shifted by increasing the effective - conjugation groups near the N^N ligand.
出处
《广州化工》
CAS
2013年第20期94-96,165,共4页
GuangZhou Chemical Industry
基金
吉林大学理论化学计算国家重点实验室开放课题基金资助(No:20130023)
