Effects of geometrical isomerism on emissive behaviour of heteroleptic cyclometalated Ir(III) complexes
Yoshiki Jinsenji1, Kazuyoshi Takimoto, Jun Yoshida
1Graduate School of Science and Engineering, Ehime University, Matsuyama 790-8577, Japan. sato.hisako.my@ehime-u.ac.jp.
Abstract:
In this study, we report the emissive properties of a heteroleptic cyclometalated Ir(iii) complex, [Ir(bzq)2(PBO)] (bzqH = benzo[h]quinoline; PBOH = 2-(2-hydroxyphenyl)benzoxazole). The complex, [Ir(C^N)2(N^O)], was synthesised and optically resolved using a chiral column. Two geometrical isomers, trans-(N,N) and cis-(N,N) isomers, were obtained as the major and minor products in an enantiopure form, respectively. Their molecular structures were determined using single crystal X-ray analysis. In the crystalline states, the intermolecular C-Hπ interaction between PBO- and an H atom in bzq- was the main factor influencing molecular packing. When the complexes were dissolved in CH2Cl2 and excited at 430 nm under N2 atmosphere, yellow (λmax = 550 nm) and orange emissions (λmax = 570 nm) were observed for the trans-(N,N) and cis-(N,N) isomers, respectively, with the quantum yield higher for the former than the latter.
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