卟啉铂配合物的结构和光谱性质的量子理论研究

Quantum Theory Research on Structures and Spectroscopic Properties of Ptcomplexes with the π-Extended Porphyrins Ligand

采用密度泛函方法研究了四个卟啉铂配合物[PtR][R=顺二苯并卟啉(DBPs,1),5,15-二苯基-顺二苯并卟啉(PDBPs,2),顺二萘并卟啉(DNPs,3),5,15-二苯基-顺二萘并卟啉(PDNPs,4)]的几何结构、电子结构和光谱特性.首先使用密度泛函方法中的3种(B3LYP、M062X和B3PW91)不同功能泛函优化了四个分子的基态(S0)几何结构,选定UB3LYP泛函优化四个分子的激发态(T1)结构.并将计算结果与相关实验数据进行比较,以评价其性能.计算得到的基态Ir—N键长和吸收值与相应的实验结果吻合较好.在TD-DFT和PCM计算水平下,得到1-4的最低能吸收和发射分别在498、507、537、545 nm和684、683、761、823 nm.其最高占据分子轨道主要占据在卟啉配体上,而最低空轨道也是π^*(R)型轨道.因此,1-4的该跃迁被指认为[π(R)→π^*(R)]电荷转移跃迁.计算结果显示出,该类配合物的发光颜色主要受卟啉配体本身的π-扩展能力控制,而受5,15位置的取代基影响较小.

The geometrical structures,electronic structures,spectroscopic properties of four red-emitting[PtR][R=syn-dibenzoporphyrins(DBPs,1),5,15-Diaryl-syn-dibenzoporphyrins(PDBPs,2),syn-dinaphthoporphyrins(DNPs,3),5,15-Diaryl-syn-dinaphthoporphyrins(PDNPs,4)complexes were investigated by DFT and TDDFT methods.We first optimized geometrical structures in ground state(S0)of four complexes,using three functionals(B3 LYP,M062 X,and B3 PW91),and the excited state(T1)structures was optimized by selected UB3 LYP functionals.The calculation results were compared with relevant experimental data to assess the performance of the functionals.The calculated bond lengths of Ir-N and absorptions in the ground state agree well with the corresponding experimental results.At the TD-DFT and PCM levels,1~4 give rise to lowest energy absorptions at 498,507,537,545 nm and phosphorescent emissions at 684,683,761,823 nm,respectively.The HOMOs of 1~4 are mainly localized on the porphyrins ligands,while the LUMOs are theπ^*(R)type orbital.Therefore,the transitions of 1~4 are all attributed to[π(R)→π^*(R)]charge transfer.It is shown that the emitting color are significantly dominated by the porphyrins ligand itself,but are minor impact by the 5,15-substituent group.