Monolayers of Biphenyl-3,4′,5-tricarboxylic Acid Formed on Cu and Ag from Solution
Monolayers of Biphenyl-3,4′,5-tricarboxylic Acid Formed on Cu and Ag from Solution
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DOI：
10.1021/acs.jpcc.5b01176
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发表时间：
2015-06-25
影响因子：
3.7
通讯作者：
Buck, Manfred
中科院分区：
文献类型：
--
作者：
Aitchison, Hannah;Lu, Hao;Buck, Manfred
采用扫描隧道显微镜、同步辐射x射线光电子能谱和近边x射线吸收精细结构能谱技术，研究了欠电位沉积Cu和Ag修饰的Au(111)/云母衬底上自组装的联苯-3,4′，5-三羧酸（BPTCA）单层。由于底物对分子间和分子间底物相互作用平衡的显著影响，BPTCA在Ag和Cu上形成明显不同的层。在Cu上形成了高度结晶相称的行结构，描述为6 x v3单元胞，相对于表面法线的分子倾斜45-50度，以及双足双齿吸附几何。相比之下，银表面形成不匹配的行结构，其特征是明显的波浪和弯曲，单足双足吸附几何形状，倾斜角度为25-30度。BPTCA与其较小的同质物苯-1,3,5-三羧酸平行，在底物特异性的单足和双足吸附几何形状上，Cu表面单层的制备条件和Ag表面的膜结构明显不同。从BPTCA的空间要求和分子对称性两个方面对结果进行了讨论。
Self-assembled monolayers of biphenyl-3,4',5-tricarboxylic acid (BPTCA) on Au(111)/mica substrates modified by underpotential deposited layers of Cu and Ag were studied by scanning tunneling microscopy under ambient conditions as well as by synchrotron-based X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy. BPTCA forms distinctly different layers on Ag and Cu due to a pronounced influence of the substrate on the balance of intermolecular and moleculesubstrate interactions. On Cu a highly crystalline commensurate row structure is formed, described by a 6 x v3 unit cell, a molecular tilt of 45-50 degrees relative to the surface normal, and a bipodal bidentate adsorption geometry. In contrast, incommensurate row structures are formed on Ag which are characterized by significant waves and kinks, a monopodal bidentate adsorption geometry, and a tilt angle of 25-30 degrees While BPTCA parallels its smaller homologue, benzene-1,3,5-tricarboxylic acid, with regard to the substrate-specific monopodal and bipodal adsorption geometries, the preparation conditions for the monolayer on Cu and the film structure on Ag are pronouncedly different. The results are discussed in terms of the steric requirements and molecular symmetry of BPTCA.