Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, Buenos Aires C1428EHA, Argentina.
Langmuir. 2010 Jan 5;26(1):173-8. doi: 10.1021/la903660y.
In recent years, self-assembled monolayers (SAMs) of selenols have been characterized using electrochemistry, scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), thermal desorption spectroscopy, and other experimental approaches. Interest in the relative stability and conductance of the Se-Au interface as compared to S-Au prompted different investigations which have led to contradictory results. From the theoretical side, on the other hand, the study of selenol-based SAMs has concentrated on the investigation of the electron transport across the Se-Au contact, whereas the structural and the thermodynamic features of the monolayer were essentially neglected. In this Article, we examine the binding of selenols to the Au(111) surface using density functional theory with plane wave basis sets and periodic boundary conditions. Our calculations provide insights on the geometry of the headgroup, the stability of the monolayer, and the electronic properties of the bond. In particular, we propose that the presence of a conjugated backbone might be a major factor determining the relative conductance at the monolayer, by differentially enhancing the intramolecular electron transport in selenols with respect to thiols. This surmise, if confirmed, would explain the conflictive data coming from the available experiments.
近年来，已采用电化学、扫描隧道显微镜（STM）、X 射线光电子能谱（XPS）、热脱附光谱等实验方法对硒醇的自组装单层（SAMs）进行了表征。与 S-Au 相比，人们对 Se-Au 界面的相对稳定性和电导率产生了兴趣，这促使人们进行了不同的研究，得出了相互矛盾的结果。另一方面，从理论角度来看，基于硒醇的 SAMs 的研究集中在研究电子在 Se-Au 接触处的传输，而单层的结构和热力学特性基本上被忽略了。在本文中，我们使用平面波基组和周期性边界条件的密度泛函理论研究了硒醇与 Au(111) 表面的结合。我们的计算提供了关于头基的几何形状、单层的稳定性和键的电子性质的深入了解。特别是，我们提出，共轭骨架的存在可能是决定单层相对电导率的一个主要因素，它通过相对于硫醇不同程度地增强硒醇中的分子内电子传输。如果这一假设得到证实，将解释来自现有实验的相互矛盾的数据。
