Color tuning associated with heteroleptic cyclometalated Ir(iii) complexes: influence of the ancillary ligand
作者:Chau-Jiun Chang、Cheng-Han Yang、Kellen Chen、Yun Chi、Ching-Fong Shu、Mei-Lin Ho、Yu-Shan Yeh、Pi-Tai Chou
DOI:10.1039/b700998d
日期:——
We report the preparation of a series of new heteroleptic Ir(III) metal complexes chelated by two cyclometalated 1-(2,4-difluorophenyl)pyrazole ligands (dfpz)H and a third ancillary bidentate ligand (L^X). Such an intricate design lies in a core concept that the cyclometalated dfpz ligands always warrant a greater ππ* gap in these series of iridium complexes. Accordingly, the lowest one-electron excitation would accommodate the π* orbital of the ancillary L^X ligands, the functionalization of which is then exploited to fine-tune the phosphorescent emission wavelengths. Amongst the L^X ligands designed, three classes (series 1–3) can be categorized, and remarkable bathochromic shifts of phosphorescence were observed by (i) replacing the 2-benzoxazol-2-yl substituent (1a) with the 2-benzothiazol-2-yl group (1b) in the phenolate complexes, (ii) converting the pyridyl group (2a) to the pyrazolyl group (2b) and even to the isoquinolyl group (2c) in the pyrazolate complexes and (iii) extending the π-conjugation of the benzimidazolate ligand from 3a to 3b. Single-crystal X-ray diffraction study on complex [(dfpz)Ir(bzpz)] (2b) was conducted to confirm their general molecular architectures. Complex 2b was also used as a representative example for fabrication of multilayered, green-emitting phosphorescent OLEDs using the direct thermal evaporation technique.
我们报告了一系列新的杂齿三价铱金属配合物的制备,这些配合物由两个环金属化的1-(2,4-二氟苯基)吡唑配体(dfpz)H和第三个辅助双齿配体(L^X)螯合而成。这种复杂设计的核心概念在于,环金属化的dfpz配体在这些铱配合物中总是能够形成更大的ππ*能隙。因此,最低的一电子激发会占据辅助L^X配体的π*轨道,其功能化则被用于微调磷光发射波长。在设计的L^X配体中,可以将三种类别(系列1-3)进行分类,通过以下方式观察到显著的红移现象:(i)在苯醇配合物中,将2-苯并恶唑-2-基取代基(1a)替换为2-苯并噻唑-2-基(1b);(ii)在吡唑配合物中,将吡啶基(2a)转化为吡唑基(2b),甚至转变为异喹啉基(2c);(iii)将苯并咪唑配体的π-共轭从3a扩展到3b。对配合物[(dfpz)Ir(bzpz)] (2b)进行了单晶X射线衍射研究,以确认其一般分子结构。配合物2b还被用作示例,采用直接热蒸发技术制造多层发光绿色磷光OLED。