以苯基吡唑为主配体的Ir配合物电子结构和光谱性质的密度泛函理论研究

Electronic Structures and Spectroscopic Properties Studies of Phosphorescent Iridium(Ⅲ) Complexes with Phenylpyrazole Ligands by Density Functional Theory

用密度泛函理论(DFT)和含时密度泛函理论(TD-DFT)的B3LYP方法对以苯基吡唑ppz为主配体的4种Ir配合物Ir(ppz)3,Ir(ppz)2(acac),Ir(ppz)2(pic)和Ir(ppz)2(dbm)的电子结构和光谱性质进行了理论研究.计算结果表明,辅助配体的改变对Ir配合物的最高占据轨道(HOMO)的影响不大,但会显著的降低分子最低空轨道(LUMO)的能级,从而调节Ir配合物的HOMO和LUMO间的能隙.4种配合物对应的发射跃迁分别为Ir(ppz)3:d(Ir)+π(ppz)→π*(ppz);Ir(ppz)2(pic):d(Ir)+(ppz)→π*(pic);Ir(ppz)2(acac),Ir(ppz)2(dbm):d(Ir)+π(acacdbm)→π*(acacdbm).金属配合物的发光颜色可以通过选择合适的辅助配体调节.

The electronic structures and spectroscopic properties ofphosphorescent Ir （Ⅲ） complexes It（ppz） 3, Ir（ppz） 2 （pie）, Ir （ppz） 2 （ acac ） and Ir （ ppz ） 2 （ dbm ） （ ppz = phenylpyrazole, pic = picolinate, acac = Pentane-2,4-dione and dbm = dibenzoylmethane）, were investigated theoretically. Density functional theory（DFT） and time dependent DFF calculations were performed on the ground and excited states of the investigated complexes to provide insight into the structural, electronic, and optical properties of these systems. Calculated results testify that ancillary ligands have little influence on the highest occupied molecular orbital （HOMO） and great effect on the lowest unoccupied molecular orbital（LUMO） by lowering the LUMO energy levels dramatically. The transition of It（ppz） 3 is attributed to d （Ir） ＋ π （ppz）→ π （ppz） ; whereas that of Ir （ ppz）2 （pic） is related to d （Ir） ＋ π （ppz） → π ^＊（ pie ） ; Ir （ ppz）2 （aeae） and Ir （ ppz）2 （dbm） are categorized as d（Ir） ＋ π （ acae/dbm）→π^＊ （aeae/dbm） charge transfer. Emission color of iridium complexes could be tuned by choosing congruent ancillary ligands.