2-氨基乙硫醇自组装单分子膜表面电离常数的FT-SERS方法测定(英文)

本文报道了采用原位傅立叶变换-表面增强拉曼散射(Fouriertransform-surfaceenhancedRamanscattering,FT-SERS)光谱技术测定在缓冲溶液和金电极界面上自组装单分子膜(self-assembledmonolayers,SAMs)的表面电离常数及其随电极电位改变的研究之初步结果。该方法通过应用FT-SERS原位光谱技术测定SAMs中质子化端基氨基的对离子ClO4特征峰强度随溶液pH值改变而变化的数值,获得相应的FT-SERS滴定曲线,进而可以确定一定条件下该SAMs功能化端基的表面电离常数。实验测定了2-氨基乙硫醇(2-aminoethanethiol,2AT)SAMs在三个不同电位下,在含有NaClO4支持电解质的Britton＆Robinson缓总溶液中的表面电离常数。实验结果揭示了在所研究的电位范围内,2ATSAMs端基氨基基团的表面pKa值随电极电位的正向增加而减小的变化规律。

Surface pKa Values of 2-Aminoethanethiol Self-assembled Monolayers Evaluated by Direct Observation of Counter Anion by FT-SERS Spectroscopy

Determination of the surface pK_a of self-assembled monolayers (SAMs) at aqueous buffer/gold interfaces, and the shift of pK_a values with the change of electrode potentials by direct observation of counter anion by Fourier transform-surface enhanced Raman scattering (FT-SERS) measurements, namely, FT-SERS titration, is reported here. Compared to the conventional contact angle titration, FT-SERS titration has the advantage of giving further insight into the microscopic and dynamic information of the surface-confined functional groups. In addition, such a technique has high sensitivity, micrometer spatial resolution, and chemical selectivity. From the analysis of pH-dependent FT-SERS spectra of 2-aminoethanethiol (2AT) monolayers on gold, its surface pK_a values under different potentials, 0.0V, 0.1V and 0.2V, were determined. It was found that the pK_a values of 2AT monolayers on gold decreased with increasing of the potential exerted.