Schultz Zachary D, Gewirth Andrew A
Department of Chemistry, University of Illinois at Urbana-Champaign, 61801, USA.
Anal Chem. 2005 Nov 15;77(22):7373-9. doi: 10.1021/ac0511593.
We report on the potential-dependent behavior of the zwitterionic molecule p-aminobenzoic acid (PABA) at a Ag(111) electrode surface. Infrared-visible sum frequency generation spectroscopy (SFG) in tandem with electrochemical capacitance and CV measurements are used to study the effects of applied potential on the adsorption and orientation of PABA. Changes in the SFG signal indicate that PABA changes orientation in response to the charge on the electrode surface, orienting one way positive of the potential of zero charge (pzc) and oppositely negative of the pzc. At positive potentials, a phase change is observed associated with the formation of a condensed layer. PABA is observed to remain on the surface at all potentials examined. These results show that the orientation of small molecules with large dipoles, like zwitterions, can be controlled by applied potential.
我们报道了两性离子分子对氨基苯甲酸（PABA）在Ag(111)电极表面的电位依赖性行为。结合电化学电容和循环伏安测量的红外-可见和频产生光谱（SFG）用于研究施加电位对PABA吸附和取向的影响。SFG信号的变化表明，PABA会根据电极表面的电荷改变取向，在零电荷电位（pzc）正向时以一种方式取向，在pzc负向时则相反取向。在正电位下，观察到与凝聚层形成相关的相变。在所研究的所有电位下，PABA都能保留在表面。这些结果表明，具有大偶极矩的小分子（如两性离子）的取向可以通过施加电位来控制。
