Spectroscopic Study of Highly Solvated Transient Complex of Methylene Blue with Reducing Sugars

The highly solvated transient complex of methylene blue (MB) with reducing sugars (RCHO)was reported through study of thermodynamic activation parameters and mass spectrum ofpurified isolated product after reduction in 50% aqueous methanol. For this purpose an opticalprocessor was used to study anaerobic reduction under monochromatic radiations of661 nm obtained via a source ofHg lamp. Four reducing sugars, two aldohexoses (glactose,mannose) and two disaccharides (lactose and maltose) were selected as reducing agents.Reaction mixtures were subjected to UV/Visible spectroscopy before and after irradiationto validate the photo reduction. IR and Mass spectrometry of leuco dye were performed to check the solvation of dye and different functional groups. IR spectroscopy showed N - Hstretching vibration at 3662 cm^-1 and bending vibration for N - H bond appeared around 1450 cm^-1 confirming the presences ofN - H bond for a secondary amine. Ultraviolet spectrashowed the change in absorbance without appreciable change in wavelength. The valuesof thermodynamics parameters like Ea, ΔG*,ΔS* and ΔH*were computed, and showed that transient complex is less disorderly oriented relative to the reactant.