Acta Phys. -Chim. Sin. ›› 2015, Vol. 31 ›› Issue (2): 245-252.

• THEORETICAL AND COMPUTATIONAL CHEMISTRY •

Second-Order Nonlinear Optical Properties of Bis-Cyclometalated Iridium(Ⅲ) Isocyanide Complexes

ZHU Chang-Li, WANG Wen-Yong, TIAN Dong-Mei, WANG Jiao, QIU Yong-Qing

1. Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun 130024, P. R. China
• Received:2014-10-20 Revised:2014-12-18 Published:2015-01-26
• Contact: QIU Yong-Qing E-mail:qiuyq466@nenu.edu.cn
• Supported by:

The project was supported by the National Natural Science Foundation of China (21173035).

Abstract:

The second-order nonlinear optical (NLO) properties of bis-cyclometalated iridium(Ⅲ) isocyanide complexes were investigated by density functional theory (DFT). In this work, the geometries of the complexes were optimized using the B3PW91(UB3PW91) functional and they were found to be in good agreement with experimental data. The 6-31G* basis set was used for the non-metal elements while the LANL2DZ basis set was used for iridium. From the optimized geometries the total first hyperpolarizabilities (βtot) of the complexes were calculated by the B3PW91(UB3PW91) and B3LYP(UB3LYP) functionals. Because the polarization and diffuse function may have a nontrivial effect on the calculation of the first hyperpolarizabiliy the more flexible and polarized 6-31+G* non-metal atom basis sets and the LANL2DZ basis set for iridium were used. The absorption spectra of all the complexes were calculated at the CAM-B3LYP(UCAM-B3LYP)/6-31+G** (LANL2DZ iridium atom) level in acetonitrile to obtain a deeper insight into the second-order NLO properties of these complexes. The results indicate that the second-order NLO response is not strongly affected by different substituents, while the redox reaction plays an important role in improving the second-order NLO response and this comes from a change in the charge transfer pattern and an increase in the degree of charge transfer. The βtot values of the one-electron oxidized/reduced species (1a2+/1a)(complexes cyclometalated with N-arylazolesand alkyl isocyanides, [(CN)2Ir(CNR)2]+ (R=CH3)) are 75 and 144 times larger than that of the eigenstate complex (1a+), respectively. Therefore, the redox reaction of the cationic bis-cyclometalated iridium isocyanide complexes can effectively tune the second-order NLO properties.

MSC2000:

• O641