Geometry and quadratic nonlinearity of charge transfer complexes in solution: A theoretical study

Mukhopadhyay, S and Pandey, Ravindra and Das, Puspendu K and Ramasesha, S (2011) Geometry and quadratic nonlinearity of charge transfer complexes in solution: A theoretical study. In: Journal of Chemical Physics, 134 (4).

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Abstract

In this paper, we have computed the quadratic nonlinear optical (NLO) properties of a class of weak charge transfer (CT) complexes. These weak complexes are formed when the methyl substituted benzenes (donors) are added to strong acceptors like chloranil (CHL) or di-chloro-di-cyano benzoquinone (DDQ) in chloroform or in dichloromethane. The formation of such complexes is manifested by the presence of a broad absorption maximum in the visible range of the spectrum where neither the donor nor the acceptor absorbs. The appearance of this visible band is due to CT interactions, which result in strong NLO responses. We have employed the semiempirical intermediate neglect of differential overlap (INDO/S) Hamiltonian to calculate the energy levels of these CT complexes using single and double configuration interaction (SDCI). The solvent effects are taken into account by using the self-consistent reaction field (SCRF) scheme. The geometry of the complex is obtained by exploring different relative molecular geometries by rotating the acceptor with respect to the fixed donor about three different axes. The theoretical geometry that best fits the experimental energy gaps, beta(HRS) and macroscopic depolarization ratios is taken to be the most probable geometry of the complex. Our studies show that the most probable geometry of these complexes in solution is the parallel displaced structure with a significant twist in some cases. (C) 2011 American Institute of Physics. doi:10.1063/1.3526748]

Item Type:	Journal Article
Publication:	Journal of Chemical Physics
Publisher:	American Institute of Physics
Additional Information:	Copyright of this article belongs to American Institute of Physics.
Keywords:	charge exchange;energy gap;light absorption;nonlinear optics;organic compounds;solutions;solvent effects;visible spectra
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	07 Apr 2011 06:37
Last Modified:	07 Apr 2011 06:37
URI:	http://eprints.iisc.ac.in/id/eprint/36017

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