【摘要】 维生素B12分子在金属电极表面的吸附特性可以反映其与金属相互作用的机理,进而为研究其在生命活动中表现出的生物化学活性提供依据。测试了维生素B12分子的正常拉曼光谱以及其吸附在不同负电位下铜电极上的表面增强拉曼散射光谱。结果表明:在不同的电极电位下,维生素B12分子在铜电极表面的吸附状态不同。在较高负电位下,维生素B12分子的钴啉环倾斜吸附在铜电极表面,Co-CN基团距离铜电极表面较远;随着电极电位的降低,钴啉环与衬底表面所呈夹角开始减小,Co-N基团和5,6二甲基苯并咪唑基团向电极表面靠近。这一结果首次提供了有关维生素B12分子与铜电极进行作用时的结构特性,并给进一步研究其电化学生物活性提供了有意义的参考价值。更多还原

【Abstract】 The Vitamin B12 molecule has long fascinated chemists because of its exclusive complex structure and unusual reactivities in biological systems.In order to achieve a better understanding of the structural attribute of the Vitamin B12 molecule when it interacted with metal,in the present paper,the Vitamin B12 molecules adsorbed on variation of copper electrode potential from 0 to-1.0 Vwas studied by surface-enhanced Raman spectroscopy(SERS).An excellent SERS substrate was obtained with insitu electrochemical oxidation-reduction cycle(ORC),and its surface roughness was characterized by atomic force microscope(AFM).Assignments of Raman peaks observed by normal Raman spectrum(NRS)and SERS spectra of Vitamin B12 molecule were given based on previous literatures.It was found that the potential-dependent relative intensity changed in SERS spectra which depended on the Vitamin B12 molecular orientation with respect to the copper surface according to the surface selection rule(SSR).It was concluded that the corrin ring was adsorbed in tilt form on copper surface and the Co-CN group was farther away from the copper surface at higher potentials.With the decrease in potential,the tilt angle between the corrin ring and copper surface became smaller,then the Co-N group and 5,6 dimethylbenzimidazole group got close to the copper surface.The results offered an important structural attribute of Vitamin B12molecule when it interacted with copper electrode for the first time,and supplied a meaningful reference for the electrochemical bioactivity of the Vitamin B12 molecule.更多还原