Neutral Cyclometalated Iridium(III) Complexes Bearing Substituted N-Heterocyclic Carbene (NHC) Ligands for High-Performance Yellow OLED Application
Neutral Cyclometalated Iridium(III) Complexes Bearing Substituted N-Heterocyclic Carbene (NHC) Ligands for High-Performance Yellow OLED Application
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DOI：
10.1021/acs.inorgchem.9b01678
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发表时间：
2019-11-04
影响因子：
4.6
通讯作者：
Sun, Wenfang
中科院分区：
文献类型：
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作者：
Liu, Bingqing;Jabed, Mohammed A.;Sun, Wenfang
报道了一系列中性环化铱（III）配合物的合成、晶体结构和物理性质，这些配合物带有取代的N-杂环卡宾（NHC）辅助配体（（CN）（2）Ir（R-NHC），其中CN和NHC分别指环金属化配体苯并[h]喹啉和1-苯基苯并咪唑）。NHC配体在苯环的C4'（R = NO_2（Ir_1），CN（Ir_2），H（Ir_3），OCH_3（Ir_4），N（CH_3）（2）（Ir_5））或苯并咪唑环的C5（R = NO_2（Ir_6），N（CH_3）（2）（Ir_7））上被吸电子或供电子基团取代。通过单晶X射线衍射分析确认了Ir 1的构型。通过光谱方法和含时密度泛函理论（TDDFT）计算研究了Ir 1-Ir 7的基态和激发态性质。所有配合物在约400 nm处均具有中等强度的无结构吸收带。440 nm处，源自基于CN配体的（1）pi，pi*/（CT）-C-1（电荷转移）/（1）d，d跃迁和超过500 nm的非常弱的自旋禁戒（MLCT）-M-3（金属-配体电荷转移）/（LLCT）-L-3（配体-配体电荷转移）跃迁。与未取代的配合物Ir 3相比，吸电子取代基引起（1）pi，pi*/（CT）-C-1/（1）d，d带轻微蓝移，而给电子取代基引起该带红移。除了弱发射的硝基取代配合物Ir 1和Ir 6具有短得多的寿命外，
The synthesis, crystal structure, and photophysics of a series of neutral cyclometalated iridium(III) complexes bearing substituted N-heterocyclic carbene (NHC) ancillary ligands ((CN)(2)Ir(R-NHC), where CN and NHC refer to the cyclo-metalating ligand benzo[h]quinoline and 1-phenylbenzimidazole, respectively) are reported. The NHC ligands were substituted with electron-withdrawing or -donating groups on C4' of the phenyl ring (R = NO2 (Ir1), CN (Ir2), H (Ir3), OCH3 (Ir4), N(CH3)(2) (Ir5)) or C5 of the benzimidazole ring (R = NO2 (Ir6), N(CH3)(2) (Ir7)). The configuration of Ir1 was confirmed by a single-crystal X-ray diffraction analysis. The ground- and excited-state properties of Ir1-Ir7 were investigated by both spectroscopic methods and time-dependent density functional theory (TDDFT) calculations. All complexes possessed moderately strong structureless absorption bands at ca. 440 nm that originated from the CN ligand based (1)pi,pi*/(CT)-C-1(charge transfer)/(1)d,d transitions and very weak spin-forbidden (MLCT)-M-3 (metal-to-ligand charge transfer)/(LLCT)-L-3 (ligand-to-ligand charge transfer) transitions beyond 500 nm. Electron-withdrawing substituents caused a slight blue shift of the (1)pi,pi*/(CT)-C-1/(1)d,d band, while electron-donating substituents induced a red shift of this band in comparison to the unsubstituted complex Ir3. Except for the weakly emissive nitro-substituted complexes Ir1 and Ir6 that had much shorter lifetimes (