Abstract:

The molecular structural parameters of indophenol and its derivatives were calculated by semi empirical molecular orbital quantum chemical method. The relation between molecular structural parameters and formal potentials was analyzed by principal factor analysis and multiple linear regression method. It was found that the formal potential of indophenols has a good relation with two cent er electron exchange energy, Eex(2), resonance energy of O-C bond, Eex(C1-O),and molecular ionization potential, Ip, among 19 molecular structural parameters. The regression equation is E0′= 1.47×10－3 Eex(two)－5.74×10－2 Eex(C1－O)－1.41 ×10－2 Ip with RC=0.9999 and SD=0.00424.It was confirmed by the relation between structure parameters and formal potentials, and the thermodynamic stability of its intermediate products that the H＋ionization is prior to the electron transfer step in the oxidation mechanism.

Key words: Indophenols, Formal potential, Molecular structural parameters, Principal factor analysis and regression, Molecular mechanism of redox reaction