New approach for evaluation optical absorption measurements of charge transfer complexes between dimethoxynaphthalenes and tetracyanoethylene: singular value decomposition method

Singular-value decomposition (SVD) method is a numerical multidimensional technique appropriate for evaluation of optical absorption measurements of 1:1 charge transfer complexes (CTCs). Matrix algebra of the absorption data for different solutions and wavenumbers is primarily used for evaluation of the equilibrium constant and to obtain some general expressions to illustrate physical significance of the results obtained. The influence of the ratio of the concentrations of donor and acceptor is examined. It can lead to information about the stoichiometry of the complex formed in solution. Calculations on data for CTCs between dimethoxynaphthalene (DMNs) and tetracyanoethylene (TCNE) in CH2Cl2 at various temperatures are described. The results suggest that there is a noticeable difference in the K4, caused by substitutions at alpha- and beta-positions, because the alpha-position of naphthalene exhibits relatively high electron density compared with the corresponding beta-position. There is a linear correlation between the donor HOMO energy and charge-transfer absorption maxima.