QUANTUM-CHEMICAL APPROACH TO THE GIBBS ENERGY OF ION TRANSFER BETWEEN2 IMMISCIBLE LIQUIDS

The linear dependence of the standard ion transfer potential Delta(O)( W) phi degrees of polyanions on their surface field strength E is eluc idated on the basis of Mulliken's charge-transfer (CT) complex theory. Quantum chemical considerations based on a simple model, where an ele ctron in the 2p orbital (HOMO) of the surface oxygen atom of the polya nion partially transfers to the 4a(1) molecular orbital (LUMO) of wate r, have shown that the CT interaction energy per primary solvent is a function of E, approximately a quadratic equation. This leads to the a pparent linear dependence of Delta(O)(W) phi degrees (exactly, the cha rge-dependent part) on E. The theoretically estimated coefficient of t he linear term is in fair agreement with the experimental value, sugge sting that the CT interaction plays the most important role in the lin ear dependence. In this paper, comments on Aoki's theory of 1995 (J. E lectroanal. Chem., 386 (1995) 17) are also offered.