CHIRAL SOLVENT STRUCTURE AROUND CHIRAL MOLECULES - EXPERIMENTAL AND THEORETICAL-STUDY

Molecular dynamics simulations of bromocamphor in n-hexane, CCl4, and CHCl3 were performed at three temperatures to establish the distributi on of the solvent molecules about the solute and to see how this chang ed with temperature. The results were used to calculate the solvent co ntribution to the circular dichroism (CD) of the solute at each temper ature. The variation in experimental CD as a function of temperature w as also measured for bromocamphor, dibromocamphor, camphor, and fencho ne in n-hexane, CCl4, and CHCl3. Since the intrinsic CD of the solute is essentially temperature independent, the variation in measured Co a s a function of temperature could be attributed solely to the solvent- induced CD. The results of calculations and experiments were used to e xplain the chiral solvent distribution induced about itself by a chira l molecule. The observed effects were able to be explained in terms of pockets around the solute being occupied by the solvent and therefore creating a dissymmetric arrangement around the optically active carbo nyl chromophore. This effect was found to be very temperature dependen t. The magnitude of the solvent effect was found to depend upon the na ture of the solute as well as the solvent.