The Effect of Complex Formation on the Static and Frequency-Dependent Nonlinear Optical Properties: A Combined Experimental and Theoretical Investigation

Abstract

A novel mixed ligand Mn(II) complex of 6-Bromopyridine-2-carboxylic acid (6Brpca) and 4,4 '-dimethyl-2,2 ' dipyridyl has been prepared and structurally characterized using single-crystal X-ray diffraction. The spectroscopic properties were also analyzed by using FT-IR and UV-Vis spectral techniques. The coordination complexes having transition metal ions are known to have promising optical nonlinearity behavior. Therefore, B3LYP level density functional theory was used to investigate first- and second-order hyperpolarizabilities (beta and gamma) and provide a deep understanding of the relation between the structure and NLO properties. The calculations of frequency-dependent alpha, beta, and gamma at frequencies of w = 0.0856252 and 0.0428126 au. for 6Brpca and Dmdpy ligands as well as Mn(II) complex have been also carried out using B3LYP/LanL2DZ level. Especially second harmonic generation (SHG) first and second hyperpolarizabilities (beta(- 2w;w,w) and gamma (-2w;w,w,0)) parameters for Mn(II) complex have been calculated as 11448 x 10(-30) and 680035 x 10(-36) esu, respectively. It has been determined that there is a tremendous increase in beta and gamma parameters when 6Brpca and Dmdpy ligands coordinate to the high spin multiplicity Mn(II) ion. Theoretical calculations revealed that the large first- and secondorder hyperpolarizabilities are caused by strong intramolecular charge transfer between the transition metal and the coordinated ligands. These results indicate that the the organometallic complex under investigation is valuable candidate for optoelectronic and photonic applications.