银电极上4-氨基安替比林原位表面增强拉曼光谱电化学

在银电极表面4-氨基安替比林(4-AAP)分子自组装,形成单分子膜层.应用表面增强拉曼散射(SERS)光谱原位考察不同电位下4-AAP在电极表面的吸附机理及其组装液pH值对组装分子与银作用方式的影响.依据密度泛函数(DFT)理论预测4-AAP分子振动模式及其SERS光谱归属.结果表明:在开路电位下,组装层中的4-AAP分子以N15和O3为位点,由苯环倾斜和比林环垂直的方式吸附在银表面;但随着外加电位负移,4-AAP分子的苯环趋于垂直吸附而比林环则逐渐以平行方式靠近银表面.在-0.8V电位下,4-AAP分子从银表面脱附.酸性溶液中组装,形成的4-AAP膜层以N15和O3为位点吸附于银表面,比林环倾斜而苯环直立;碱性条件下,分子的吸附位点不变,比林环呈平行取向,而苯环倾斜于银表面.

In-situ Surface Enhanced Raman Scattering Electrochemical Investigation of 4-aminoantipyrine on Silver Electrode

In this paper,4-AAP was self-assembled on silver surface to form monolayers. Surface-enhanced Raman Spectroscopy ( SERS) was used to in-situ investigate the adsorption mechanism of the 4-aminoantipyrine( 4-AAP) on silver surface dependent on shifting potentials and the effect of solution pH. Based on density functional theory( DFT) calculation of vibration modes,approximate assignment of 4-AAP SERS spectrum was conducted. In situ SERS spectral electrochemical experiments indicated that the 4-AAP monolayers experience a dynamic adsorption process from a tilted fashion to a more vertical mode for benzene ring and more parallel for pyrine ring with the potential applied toward more negative voltages. The complete desorption of 4-AAP from the silver surface happened as the potentials was applied at - 0. 8 V. The 4-AAP SAMs formed in acid medium anchoring at the silver surface via N15 and O3 atoms in a perpendicular fashion for the benzene ring and the tilted mode for pyrine ring. In case of the alkaline solution,benzene ring tended to being more perpendicular while pyrine ring parallel to the silver surface.