Martínez-Alonso Marta, Cerdá Jesús, Momblona Cristina, Pertegás Antonio, Junquera-Hernández José M, Heras Aránzazu, Rodríguez Ana M, Espino Gustavo, Bolink Henk, Ortí Enrique
Departamento de Química, Facultad de Ciencias, Universidad de Burgos , Plaza Misael Bañuelos s/n, 09001 Burgos, Spain.
Instituto de Ciencia Molecular, Universidad de Valencia , Catedrático José Beltrán 2, 46980 Paterna, Spain.
Inorg Chem. 2017 Sep 5;56(17):10298-10310. doi: 10.1021/acs.inorgchem.7b01167. Epub 2017 Aug 24.
A series of bis-cyclometalated iridium(III) complexes of general formula [Ir(ppy)(NN)][PF] (ppy = 2-phenylpyridinate; NN = 2-(1H-imidazol-2-yl)pyridine (1), 2-(2-pyridyl)benzimidazole (2), 1-methyl-2-pyridin-2-yl-1H-benzimidazole (3), 2-(4'-thiazolyl)benzimidazole (4), 1-methyl-2-(4'-thiazolyl)benzimidazole (5)) is reported, and their use as electroluminescent materials in light-emitting electrochemical cell (LEC) devices is investigated. [2][PF] and [3][PF] are orange emitters with intense unstructured emission around 590 nm in acetonitrile solution. [1][PF], [4][PF], and [5][PF] are green weak emitters with structured emission bands peaking around 500 nm. The different photophysical properties are due to the effect that the chemical structure of the ancillary ligand has on the nature of the emitting triplet state. Whereas the benzimidazole unit stabilizes the LUMO and gives rise to a MLCT/LLCT emitting triplet in [2][PF] and [3][PF], the presence of the thiazolyl ring produces the opposite effect in [4][PF] and [5][PF] and the emitting state has a predominant LC character. Complexes with MLCT/LLCT emitting triplets give rise to LEC devices with luminance values 1 order higher than those of complexes with LC emitting states. Protecting the imidazole N-H bond with a methyl group, as in complexes [3][PF] and [5][PF], shows that the emissive properties become more stable. [3][PF] leads to outstanding LECs with simultaneously high luminance (904 cd m), efficiency (9.15 cd A), and stability (lifetime over 2500 h).
报道了一系列通式为[Ir(ppy)(NN)][PF]的双环金属化铱(III)配合物（ppy = 2-苯基吡啶酸酯；NN = 2-(1H-咪唑-2-基)吡啶(1)、2-(2-吡啶基)苯并咪唑(2)、1-甲基-2-吡啶-2-基-1H-苯并咪唑(3)、2-(4'-噻唑基)苯并咪唑(4)、1-甲基-2-(4'-噻唑基)苯并咪唑(5)），并研究了它们作为发光电化学电池(LEC)器件中的电致发光材料的用途。[2][PF]和[3][PF]是橙色发射体，在乙腈溶液中于590 nm左右有强烈的无结构发射。[1][PF]、[4][PF]和[5][PF]是绿色弱发射体，有结构发射带，在500 nm左右达到峰值。不同的光物理性质归因于辅助配体的化学结构对发射三重态性质的影响。苯并咪唑单元使最低未占分子轨道稳定，并在[2][PF]和[3][PF]中产生MLCT/LLCT发射三重态，而噻唑基环的存在在[4][PF]和[5][PF]中产生相反的效果，发射态具有主要的LC特征。具有MLCT/LLCT发射三重态的配合物产生的LEC器件的亮度值比具有LC发射态的配合物高1个数量级。如在配合物[3][PF]和[5][PF]中那样用甲基保护咪唑N-H键，表明发射性质变得更稳定。[3][PF]导致出色的LEC，同时具有高亮度(904 cd m)、效率(9.15 cd A)和稳定性（寿命超过2500小时）。
