二苯基脲类化合物在银电极上吸附行为的SERS研究

利用表面增强拉曼光谱(SERS)方法分别研究了二苯基胍(DPGA)、二苯基脲(DPU)和二苯基硫脲(DPTU)在硫酸溶液中银电极表面上的吸附行为。结果表明:质子化的DPGA通过苯环的π电子作用吸附,吸附取向为平行吸附;DPU通过N原子上的p π电子作用吸附,吸附取向为倾斜吸附;DPTU通过苯环上的p π电子作用吸附,吸附取向为平行吸附。三种有机物的结构与吸附行为的关系也被讨论。

SERS Study of Adsorption of Diphenylguanidine and Diphenylurea and Diphenylthiourea on Silver Electrode

The adsorption behaviors of N,N diphenylguanidine (sym DPGA)?N,N diphenylurea(sym DPU) and N,N diphenylthiourea (sym DPTU) on the silver electrode in sulphuric acid were investigated by means of SERS spectra. First of all, the adsorption characteristics of three kinds of diphenyl compound(sym DPGA?sym DUP and sym DPTU) on the silver electrode were studied by analyzing the correlation between the electrode potential and SERS spectrum peak. Different function groups lead to different adsorption behaviors. Because DPGA is apt to protonate, protonated DPGA is adsorbed on the silver surface in parallel orientation by the π electron interaction of the aromatic ring. Compared with DPU, the conjugate extent of N atom of secondary amine group in DPTU is greater than that in DPU, which leads to the adsorption of DPTU in parallel orientation by the p π electron interaction of the aromatic ring. But DPU adsorbs on the silver surface in inclined orientation by p π electron interaction of the nitrogen atom because of space barrier.