Coenzyme And The Phytic Acid Molecule With The Metal Surface Interaction Raman Spectroscopy Study

The confocal laser Raman microspectroscope has high spatial resolution and sensitivity as well as SERS can provide the information of at monolayer at molecular level. In addition, self-assembled monolayers (SAMs) technique can present a uniform and order molecular array as a well defining mode for surface study. In this thesis, the three methods mentioned above, were employed together to observe the mechanism and phenomenon of surface process.Under different experiment conditions, SERS spectra of coenzyme NAD⁺ and phytic SAMs on the metal surface were obtained. Based on the calculation results for vibration by quantum chemistry methods along with the SERS mechanism, the adsorption structure of the monolayers at the metallic surface could be deduced. And also, the electrochemical and in situ spectroelectrochemical methods are used to investigate the relationships of structure-properties and examine the stability of monolayers. The main contents of this thesis include the following parts:Rare earth is applied widely and its biochemical effects as a hot spot are concerned. Charged silver surface could serve as the bio-mimic interface and the influence of Ce(III) on the structure of NAD⁺ monolayer at that surface was investigated by SERS study for understanding the mechanism of interaction between rare earth ion and coenzyme adsorbed on the bio-membranes. After the Ce(III) added in the obtained SERS spectra, it is found that, the change of the peaks are almost related to the vibrational modes of ribose and phosphate groups, it could be suggested that NAD⁺ form complexes with Ce(III), leading that the nicotinamide moiety left away from the surface.Phytic acid (IP₆) is an environmentally friendly anti-corrosive agent. Six phosphate groups of IP₆ molecule possess the chelating capability with metal and the configuration of IP₆ in solution is dependent of the pH value. Phytic acid monolayers self-assembled at the different metal surfaces were observed by the SERS spectroscopy and electrochemistry. On the basis of results of SERS mapping and quantum chemistry calculation, one concludes that in a solution of pH 1.27, IP₆ tends to anchor at the silver surface via one phosphate group to assemble the monolayers and under pH=13, it adsorbs chemically at the surface through four...