Rodríguez González Miriam C, Carro Pilar, Pensa Evangelina, Vericat Carolina, Salvarezza Roberto, Hernández Creus Alberto
Área de Química Física, Departamento de Química, Facultad de Ciencias, Universidad de La Laguna, Instituto de Materiales y Nanotecnología, 38200-, La Laguna, Tenerife, Spain.
Instituto de Investigaciones Fisicoquímicas, Teóricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, Universidad Nacional de La Plata-CONICET- Sucursal 4, Casilla de Correo 16, 1900, La Plata, Argentina.
Chemphyschem. 2017 Apr 5;18(7):804-811. doi: 10.1002/cphc.201601313. Epub 2017 Feb 13.
The dynamics of the self-assembly process of thiol molecules on Au(111) is affected by the interplay between molecule-substrate and molecule-molecule interactions. Therefore, it is interesting to explore the effect of a second anchor to the gold surface, in addition to the S atom, on both the order and the feasibility of phase transitions in self-assembled monolayers. To assess the role of an additional O anchor, we have compared the adsorption of two mercaptobenzoic acid isomers, 2-mercaptobenzoic acid (2-MBA) and 4-mercaptobenzoic acid (4-MBA), on Au(111). Results from scanning tunneling microscopy, X-ray photoelectron spectroscopy, electrochemical techniques, and density functional theory calculations show that the additional O anchor in 2-MBA hinders surface mobility, reducing domain size and impeding the molecular reorganization involved in phase transition to denser phases on the Au(111) substrates. This knowledge can help to predict the range order and molecular density of the thiol SAM depending on the chemical structure of the adsorbate.
硫醇分子在Au(111)上的自组装过程动力学受分子-底物和分子-分子相互作用之间相互影响。因此，除了S原子外，探索第二个与金表面结合的基团对自组装单分子层中相变的有序性和可行性的影响很有意思。为了评估额外的O结合基团的作用，我们比较了两种巯基苯甲酸异构体，即2-巯基苯甲酸（2-MBA）和4-巯基苯甲酸（4-MBA）在Au(111)上的吸附情况。扫描隧道显微镜、X射线光电子能谱、电化学技术和密度泛函理论计算结果表明，2-MBA中额外的O结合基团阻碍了表面迁移率，减小了畴尺寸，并阻碍了Au(111)衬底上向更致密相的相变过程中涉及的分子重组。这一知识有助于根据吸附质的化学结构预测硫醇自组装单分子层的有序范围和分子密度。
