高效发光材料[(C^N)2IrL]+阳离子配合物的结构和光谱特征

从理论上研究了一系列Ir(Ⅲ)[(C^N)2IrL]+[C^N=ppy, L=pzpy(1); C^N=dfppy, L=pzpy(2); C^N=ppy, L=pybi(3); C^N=tpy, L=acac(4); 其中ppy=2-苯基吡啶, dfppy=2-(2,4-双氟苯基)吡啶, pzpy=2-吡唑基吡啶, pybi=1-苯基-2-(吡啶基)-1H-苯并咪唑, tpy=2-(4-甲苯基)-吡啶, acac=乙酰丙酮]配合物的结构和光谱特征. 分别在B3LYP/LanL2DZ和CIS/LanL2DZ计算水平下优化了它们的基态和激发态结构. 计算得到的Ir-N, Ir-C和Ir-O基态键长和相应实验值符合较好. 在激发态下, Ir-N和Ir-C键长增加了约0.0003~0.003 nm, 而Ir-O键长则缩短了约0.0012 nm. 在含时密度泛函理论(TD-DFT)计算水平下, 结合极化连续介质模型(PCM), 得到配合物1~4的最低能的吸收和发射分别出现在398 nm(1), 370 nm(2), 419 nm(3)和437 nm(4)以及511 nm(1), 457 nm(2), 602 nm(3)和479 nm(4). 配合物1, 2, 4的跃迁属于d(Ir)+π(C^N)→π*(C^N)的电荷转移跃迁, 而化合物3的跃迁则归因于d(Ir)+π(C^N)→π*(pybi)的电荷转移跃迁. 这表明此类配合物的吸收和发射主要受前线分子轨道的金属成分控制, 同时也受辅助配体L的影响.

Structures and Spectroscopic Properties of Highly Efficient Luminescence Material Cationic [ (C^N) 2 IrL ] + Complexes

A series of iridium(Ⅲ) complexes [(C^N)2IrL]+[C^N=ppy, L=pzpy(1); C^N=dfppy, L=pzpy(2); C^N=ppy, L=pybi(3); C^N=tpy, L=acac(4); ppy=2-phenyl-pyridine, dfppy=2-(2,4-difluorophenyl)pyridine, pzpy=2-(1H-pyrazol-1-yl)pyridine, pybi=1-phenyl-2-(pyridin-2-yl)-1H-benzoimidazole, tpy=2-(4-tolyl)-pyridine, acac=acetoylacetonate] was investigated theoretically to explore their electronic structures and spectroscopic properties. Their structures in the ground and excited states were optimized at the B3LYP/LanL2DZ and CIS/LanL2DZ levels, respectively. The results indicate that the calculated bond lengths of Ir—N, Ir—C, and Ir—O in the ground state agree well with the corresponding experimental results. Upon excitation, the bond lengths of Ir—N and Ir—C lengthen by 0.0003—0.003 nm and that of Ir—O shortens by ca. 0.0012 nm compared with those of ground states. At the time-dependent density functional theory(TD-DFT) level with the polarized continuum model(PCM), complexes 1—4give rise to lowestying absorptions at 398 nm(1), 370 nm(2), 419 nm(3), and 437 nm(4) and phosphorescent emissions at 511 nm(1), 457 nm(2), 602 nm(3), and 479 nm(4), respectively. The transitions of complexes 1, 2 and 4 are attributed to d(Ir)+π(C^N)→π*(C^N) charge transfer, whereas those of complex 3 are related to d(Ir)+π(C^N)]→π*(pybi). It is shown that the emissions are significantly dominated by the metal participating in the frontier molecular orbitals and affected by the L ligands.