Issue 19, 2007
From the journal:

Dalton Transactions

Color tuning associated with heteroleptic cyclometalated Ir(iii) complexes: influence of the ancillary ligand†

Chau-Jiun Chang,a   Cheng-Han Yang,a   Kellen Chen,a   Yun Chi,*a   Ching-Fong Shu,*b   Mei-Lin Ho,c   Yu-Shan Yehc  and  Pi-Tai Chou*c  

* Corresponding authors

a Department of Chemistry, National Tsing Hua University, Hsinchu 300, Taiwan
E-mail: ychi@mx.nthu.edu.tw
Fax: +886-3-772-0864
Tel: +886-2-571-2956

b Department of Applied Chemistry, National Chiao Tung University, Hsinchu 300, Taiwan
E-mail: shu@cc.nctu.edu.tw
Fax: +886-3-572-3764
Tel: +886-3-571-2121 ext. 56544

c Department of Chemistry, National Taiwan University, Taipei 106, Taiwan
E-mail: chop@ntu.edu.tw
Fax: +886-2-23695208
Tel: +886-2-33663894

Abstract

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.

Graphical abstract: Color tuning associated with heteroleptic cyclometalated Ir(iii) complexes: influence of the ancillary ligand

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Article information

DOI
https://doi.org/10.1039/B700998D
Article type
Paper
Submitted
22 Jan 2007
Accepted
28 Feb 2007
First published
23 Mar 2007

Dalton Trans., 2007, 1881-1890

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Color tuning associated with heteroleptic cyclometalated Ir(III) complexes: influence of the ancillary ligand

C. Chang, C. Yang, K. Chen, Y. Chi, C. Shu, M. Ho, Y. Yeh and P. Chou, Dalton Trans., 2007, 1881 DOI: 10.1039/B700998D

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