DFT/TD‐DFT investigation on Ir(III) complexes with N‐heterocyclic carbene ligands: Geometries, electronic structures, absorption, and phosphorescence properties
DFT/TD‐DFT investigation on Ir(III) complexes with N‐heterocyclic carbene ligands: Geometries, electronic structures, absorption, and phosphorescence properties
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DOI：
10.1002/jcc.21360
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发表时间：
2009-06
影响因子：
3
通讯作者：
Tao Liu;B. Xia;Qingchuan Zheng;Xin Zhou;Qingjiang Pan;Hong-Xing Zhang
中科院分区：
文献类型：
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作者：
Tao Liu;B. Xia;Qingchuan Zheng;Xin Zhou;Qingjiang Pan;Hong-Xing Zhang
对铱（III）与氮杂环配体fac-Ir（pmb）3（1），mer-Ir（pmb）3（2），（pmb）2 Ir（acac）（3），mer-Ir（pypi）3（4），fac-Ir（pypi）3（5）[pmb = 1-苯基-3H-苯并咪唑啉-2-亚基，acac =乙酰基丙酮，pypi = 1-苯基-5H-苯并咪唑啉-2-亚基; fac =面基，mer =双醛]的配合物进行了理论研究.分别用限制性和非限制性密度泛函理论（DFT）方法优化了1-5的基态和激发态几何结构（对于Ir原子为LANL 2DZ，对于其它原子为6 - 31 G）. 1-3的HOMO（最高占据分子轨道）由d（Ir）和π（苯基）组成，而4和5的HOMO由d（Ir）和π（卡宾）组成。1、2、4和5的LUMO（最低未占分子轨道）位于卡宾上，而3的LUMO位于acac上。基于Perdew-Burke-Erzenrhof（PBE）泛函1（310 nm）、2（332 nm）和3（347 nm）的TD-DFT方法计算的最低激发态具有ML卡宾CT/IL苯基→卡宾CT（MLCT =金属-配体电荷转移; ILCT =配体内电荷转移）转变特征，而4（385 nm）和5（389 nm）的那些归属于ML卡宾CT/IL卡宾→卡宾CT跃迁。用TD-DFT方法计算了PBE 0泛函1（386 nm）和2（388 nm）的磷光来自3 ML卡宾CT/3 IL苯基→卡宾CT激发态，而PBE 0泛函4（575 nm）和5（578 nm）的磷光来自3 ML卡宾CT/3 IL卡宾→卡宾CT激发态。计算结果表明，卡宾和苯基在跃迁过程中是两个独立的发色团。与1和2相比，4和5的吸收峰由于C卡宾原子附近有效π共轭基团的增加而发生红移。我们推测（pmb）2 Ir（acac）是非发射性的，因为3的LUMO是由非发射性的acac配体贡献的。© 2009威利期刊公司.《计算化学杂志》，2010年
Iridium(III) complexes with N‐heterocyclic (NHC) ligands including fac‐Ir(pmb)3 (1), mer‐Ir(pmb)3 (2), (pmb)2Ir(acac) (3), mer‐Ir(pypi)3 (4), and fac‐Ir(pypi)3 (5) [pmb = 1‐phenyl‐3H‐benzimidazolin‐2‐ylidene, acac = acetoylacetonate, pypi = 1‐phenyl‐5H‐benzimidazolin‐2‐ylidene; fac = facial, mer = meridional] were investigated theoretically. The geometry structures of 1–5 in the ground and excited state were optimized with restricted and unrestricted DFT (density functional theory) methods, respectively (LANL2DZ for Ir atom and 6‐31G for other atoms). The HOMOs (highest occupied molecular orbitals) of 1–3 are composed of d(Ir) and π(phenyl), while those of 4 and 5 are contributed by d(Ir) and π(carbene). The LUMOs (lowest unoccupied molecular orbitals) of 1, 2, 4, and 5 are localized on carbene, but that of 3 is localized on acac. The calculated lowest‐lying absorptions with TD‐DFT method based on Perdew‐Burke‐Erzenrhof (PBE) functional of 1 (310 nm), 2 (332 nm), and 3 (347 nm) have MLcarbeneCT/ILphenyl→carbeneCT (MLCT = metal‐to‐ligand charge transfer; ILCT = intraligand charge transfer) transition characters, whereas those of 4 (385 nm) and 5 (389 nm) are assigned to MLcarbeneCT/ILcarbene→carbeneCT transitions. The phosphorescences calculated by TD‐DFT method with PBE0 functional of 1 (386 nm) and 2 (388 nm) originate from 3MLcarbeneCT/3ILphenyl→carbeneCT excited states, but those of 4 (575 nm) and 5 (578 nm) come from 3MLcarbeneCT/3ILcarbene→carbeneCT excited states. The calculated results showed that the carbene and phenyl groups act as two independent chromophores in transition processes. Compared with 1 and 2, the absorptions of 4 and 5 are red‐shifted by increasing the effective π‐conjugation groups near the Ccarbene atom. We predicated that (pmb)2Ir(acac) is nonemissive, because the LUMO of 3 is contributed by the nonemissive acac ligand. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010