Essay On Electrostatics

3. RESULTS AND DISCUSSION Investigation of solubility parameters and study of components of solute-solvent interactions is of immense help in the formulation of medicinally important compounds. Inter- molecular interactions of molecules control the structure and binding and hence they play important role to communicate and control their activities. Such interactions include several components. Among the various components, electrostatic interactions are of special importance because of their long range and their influence on polar or charged molecules. Continuum model for polar and non-polar solvation generally attempts to solve the electrostatics in dielectric medium. For this purpose, the electrostatic interaction, dispersion energy and repulsion energy of four vitamins in ten different solvents are evaluated by PCM. These quantities typically converge quickly during a

Analysis of cavitation energy data in table A5 reveals that the cavitation energy depends on structure of solute as well as nature of solvent. Damian et al suggested that the cavitation energy is linearly related to surface tension and area of cavity as
∆Gcav = γ S(ρ0) (3.1)
In equation (3.1), where γ is the surface tension and S(ρ0) is the surface of the same cavity employed in the electrostatic part of the solvation energy and is defined by an isosurface of the charge density [19]. Hence, cavitation energy of a given vitamin can be correlated with the macroscopic surface tension of the solvent. Thus cavitation energy of a particular solute is high in water which has high surface tension and it is low in chloroform which has low surface tension. In a given solvent, the order of cavitation energy is biotin > phylloquinone > pyridoxine > L-ascorbic acid.
The free energy of solution for the PCM solvated molecule equation (3.2) is defined as
∆Gsol= ∆Gel+∆Gcav+∆Gdisp+∆Grep