Self-assembled Monolayers, Electrochemical Studies Of Schiff Base

Self-assembled monolayers(SAMs) of two short-chain molecules and self-assembled monolayers of Schiff bases were studied in this paper. It was investigated by the electrochemical method that the special cyclic voltammetric behavior of self-assembled monolayers(SAMs) of two short-chain molecules in Fe(CN)6^3-/4- solution and the response in Fe(CN)6(3-/4-) solution of different pH; electrochemical behavior of schiff bases self-assembled monolayers in a buffer solution with varying pH. Main results are as follows:First, two short-chain molecules of cysteamine and 4-Aminothiophenol with -NH2 were modified on gold electrode by self-assembled monolayers. When they were studied by cyclic voltammetry, it was found that peak current increased and the peak separation decreased. The surface pK_b of the self-assembled monolayers of cysteamine and 4-Aminothiophenol were 2.4+0.2 and 4.7+0.2 respectively by the electrochemical titration method. The reason that the surface pK_b of the self-assembled monolayers was lower than pK_b of -NH₂ at free state was explained.Secondly, two kinds of Schiff bases were synthesized and modified on gold by means of self-assembled monolayers(SAMs). Cyclic voltammetric technique was used to investigate the electrochemical behavior and stability of the two kinds of modified electrode in a B-R buffer in a pH range of 2.0-12.0. The results demonstrated that in a pH range of 2.0-10.0 Hydrolytic cleavage of -C=N- group in two kinds of Schiff bases occurred and in a pH range of 10.0-12.0 a irreversible reduction peak of -C = N- group appeared at -1.067V and -1.105V respectively.