Electrochemistry And In-situ FTIR Spectrochemistry Studies On Paeonol And A Series Of Quinones

Achievements of electrochemical studies of quinone compounds and phenoliccompounds were reviewed firstly in this paper. These two type compounds wererelevant through redox cycling. There are carbonyl groups (C=O) and hydroxylgroups (-OH), which are active center in redox cycling. Most of them areelectroactive molecules which play an important role in redox electron-transportchains of living systems and can be used in molecular electronics. Paeonol, and aseries of quinones (1, 4-Benzoquinone,β-1, 2-Naphthoquinone, TanshinoneⅡA), withrepresentative electrochemical characters were chosen as our research subject. Thispaper mainly covered the following research works:1, The electrochemical behaviours of paeonol on different solid electrodes werestudied by cyclic voltammetry in alkaline PBS solution. Comparative studies werecarried out by using phenol under similar experimental conditions. The paeonolelectrochemistry oxidation is irreversible, which produces a compact insulatedpolymeric film on the electrode surface, and the electrochemistry oxidation dynamicprocess was studied on ultramicroelectrode. The insulated polymeric film was provedpolymer arylether by real-time in-situ rapid scan IR spectroscopy. The insulatedpolymeric film modified platinum electrode was studied by electrochemicalimpedance techniques.2, In-situ rapid scan FTIR and In-situ difference FTIR Spectroelectrochemistrytechniques were used to track the whole electrochemical redox process of the BQ asvariable time and potential. The intermediate semiquinone anion radical appearanceand disappearance were clearly observed. Two-dimension (2D) spectral correlationanalysis was employed to determine the sequence of spectral emergence shown inrapid scan FTIR spectra. The result showed us a new insight into BQ electrochemicalreduction reaction mechanism. The relationship between the intermediate existent lifeand the temperature was studied. Based on the results, a kinetics simulation wasperformed according to the electrochemical reaction mechanism, and kineticparameter is concident with the Arrhenuis equation Arrhenius equation (k=Ae^-E/RT). 3, Electrochemical characters of two types of ortho-quinones were studied bycyclic voltammetry, differential pulse voltammetry, chronocoulometry, doublepotential step chronamperomery and so on. In-situ FTIR was also employed as apowerful tool in obtaining information on structural and moclecular properties duringthe process of electrochemical reaction. Compared with BQ, The electrochemicalprocess of ortho-quinones is not a simple two-step one-electron cathodic reduction.Actually there are some other complicated chemical processes, such as: semiquinoneradical dimerization, semiquinone radical protonation, and so on, followed byelectrochemical reduction.