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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。
In this paper, a series of [Os (PH3) 2 (CN) 2 (N ^ N)] [N ^ N = bpy (1); N ^ N = phbpy , 2’-bipyridine; phbpy = 4,4-bis-phenyl-2,2’-bipyridyl] complexes. The lowest singlet absorption and phosphorescence emission of the two complexes were obtained at 471 (1), 487 (2) nm and 619 (1), 661 (2) nm using PBE functionalization in time- . The high-energy occupied molecular orbitals 1 and 2 are predominately occupied by the metal Os and CN ligands, while the low-energy unoccupied molecular orbital is dominated by the N ^ N ligand component. Therefore, the minimum energy absorptions of 1 and 2 are considered as MLCT transitions and are mixed There is a small amount of LLCT perturbation, and its most intense high energy absorption appears as a charge transfer transition within the ligand (bipyridine). The calculated results show that CN and bipyridyl ligands play two independent chromophores during the transition. Compared with molecule 1, due to the π-conjugated effect of 2 on the bipyridyl ligand, it leads to red-shift of its absorption and emission.