Computational studies on nonlinear optical properties of metal complexes containing azobenzene

Abstract

Ruthenium complexes containing different azobenzene derivatives with different substituents provide different nonlinear optical (NLO) properties. A computational study through the Hartree-Fock (HF) method based on a 3-21G level and the density functional theory (DFT) methods based on LANL2DZ/6-31G level were used in the investigation to reduce cost and time of the experimental investigation. It was discovered that DFT-based calculations were more accurate than the HF method based on the result of bond length and bond angle obtained after the geometry optimization of three ruthenium-azobenzene complexes; complex A, complex B, and complex C. The investigation through the DFT method revealed that the three complexes possess a high NLO property based on the value of total frequency-dependent first hyperpolarizability, βtot obtained at the wavelength of 1064 nm contributed by the electron delocalization effect, due to the presence of a strong electron donating and withdrawing group in the azobenzene derivatives. It was revealed that Complex C possessed the highest NLO property with a βtot value of 12414.87 x10-30 esu followed by complex A (11828.63x10-30 esu) and Complex B (3372.10 x10-30 esu). The influence of the different structures of azobenzene containing metal to enhance the strength of nonlinear optical properties through NLO calculation has been successfully performed by the DFT method. The high NLO property of complex C was contributed by the-O(C=O)R group, which is a moderate electron-donating group (EDG) and an amine group, which is a strong EDG especially when its hydrogen group is replaced by the alkyl group.