STUDIES ON THE INTERACTION BETWEEN PHOTOS ENSITIZER METHYLENE-BLUE AND DIFFERENT ORGANIC-SOLVENTS

The spectrophotometric characteristics of methylene blue in different organic solvents have been studied in this paper. From application of Kasha's theory on the difference spectrum between MB monomer and dimer , we have estimated that the distance between monomer planes of MB ran ges from 1.345 nm to 1.425 nm and these planes form the cross angle 82 .9 similar to 87.5 degrees in dimer molecules. In order to obtain info rmation on the solution state of different solvents with methylene blu e, interaction between different solvents and MB have been investigate d by the analysis of UV-Vis absorption spectra in terms of a modified McRas's equation, The sum of the dispersion and induction force of the MB estimated from the equation is 21.3 kJ/mol, the orientation force as 20.5 kJ/mol, the hydrogen bonding as 0.17 kJ/mol in ethanol solutio n. The sum of the dispersion and induction force of the MB estimated f rom the equation is 25.9 kJ/mol, the orientation force as 20.1 kJ/mol in dimethyl sulfoxide solution.