QUANTUM MECHANICAL DESCRIPTION OF THE VARIOUS PHOTOCHEMICAL AND PHOTOPHYSICAL PROCESSES IN ASCORBIC ACID IN THE PRESENCE OF SOME WATER SOLUBLE VITAMINS

Abstract

Action of UV & visible light has been carried out on vitamin C (Ascorbic acid) in the presence of some water soluble vitamins (B1,B2,B6 and B12) in the solid and liquid phase (water as a solvent). Various physical properties such as pH, refractive index, viscosity and conductance before and after irradiation were measured for comparison and for kinetic purpose. X-ray diffraction of solid vitamins for different situations were also carried out and Bragg’s angle θ, interplanar distance d, Miller Indices hkl were calculated using suitable computer programs. Further more results obtained form UV and IR spectroscopy combined with X-ray different, were used as a data source for the programs GAMESS, MOPAC, IR PLUS, SHELX and MOLDY to obtain many possible quantum mechanical parameters, possible energies for excited states, wavefunctions, singlet and triplet energies, eigen vectors, etc. Molecular mechanics and quantum mechanics results were also obtained and bond length, angel torsion angle for all grounds states and excited states were calculated along with three dimensional structures of vitamins in different situations. Finally a proposed mechanistic scheme was developed for all vitamins.