National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan.
Phys Chem Chem Phys. 2023 Apr 26;25(16):11331-11337. doi: 10.1039/d3cp00790a.
Understanding the interactions between the adsorbate and substrate is critical in basic and advanced scientific fields, including the formation of well-organised nanoarchitectures self-assembly on surfaces. In this study, the interactions of -alkanes and -perfluoroalkanes with circumcoronene were studied using dispersion-corrected density functional theory calculations as models of their adsorption on graphite. The interactions of -perfluoroalkanes with circumcoronene were significantly weaker than those of the corresponding -alkanes, the calculated adsorption energies of -perfluorohexane and -hexane were -9.05 and -13.06 kcal mol, respectively. The dispersion interactions were the major source of attraction between circumcoronene and the adsorbed molecules. Larger steric repulsion of -perfluoroalkanes compared to those of -alkanes increased their equilibrium distances from circumcoronene and decreased the dispersion interactions, resulting in weaker interactions. The interactions between two adsorbed -perfluorohexane molecules and those of -hexane molecules were -2.96 and -2.98 kcal mol, respectively, which are not negligible in the stabilisation of adsorbed molecules. The geometries of adsorbed -perfluoroalkane dimers revealed that the equilibrium distance between two -perfluoroalkane molecules did not match the width of the six-membered rings in circumcoronene, in contrast to that between -alkanes. The lattice mismatch also destabilised the adsorbed -perfluoroalkane dimers. The difference in the adsorption energy between flat-on and edge-on orientations of -perfluorohexane was smaller than that of corresponding -hexane.
理解吸附物与基底之间的相互作用在基础科学和高级科学领域都至关重要，包括在表面上自组装形成有序纳米结构。在这项研究中，使用色散校正密度泛函理论计算研究了 -链烷烃和 -全氟链烷烃与冠状烷之间的相互作用，作为它们在石墨上吸附的模型。 -全氟链烷烃与冠状烷之间的相互作用明显弱于相应的 -链烷烃，-全氟己烷和 -己烷的计算吸附能分别为-9.05 和-13.06 kcal mol。色散相互作用是冠状烷和吸附分子之间吸引力的主要来源。与 -链烷烃相比，-全氟链烷烃的较大空间位阻增加了它们与冠状烷的平衡距离，并降低了色散相互作用，导致相互作用减弱。两个吸附的 -全氟己烷分子之间的相互作用和 -己烷分子之间的相互作用分别为-2.96 和-2.98 kcal mol，这在吸附分子的稳定化中不可忽略。吸附的 -全氟链烷烃二聚体的几何形状表明，两个 -全氟链烷烃分子之间的平衡距离与冠状烷的六元环宽度不匹配，而与 -链烷烃不同。晶格失配也使吸附的 -全氟链烷烃二聚体不稳定。-全氟己烷的面向上和边缘向上取向之间的吸附能差异小于相应的 -己烷。
