Stock Philipp, Utzig Thomas, Valtiner Markus
Max-Planck-Institut für Eisenforschung GmbH, Department for Interface Chemistry and Surface Engineering, D-40237 Düsseldorf, Germany.
Phys Chem Chem Phys. 2017 Feb 8;19(6):4216-4221. doi: 10.1039/c6cp07562b.
In all realms of soft matter research a fundamental understanding of the structure/property relationships based on molecular interactions is crucial for developing a framework for the targeted design of soft materials. However, a molecular picture is often difficult to ascertain and yet essential for understanding the many different competing interactions at play, including entropies and cooperativities, hydration effects, and the enormous design space of soft matter. Here, we characterized for the first time the interaction between single hydrophobic molecules quantitatively using atomic force microscopy, and demonstrated that single molecular hydrophobic interaction free energies are dominated by the area of the smallest interacting hydrophobe. The interaction free energy amounts to 3-4 kT per hydrophobic unit. Also, we find that the transition state of the hydrophobic interactions is located at 3 Å with respect to the ground state, based on Bell-Evans theory. Our results provide a new path for understanding the nature of hydrophobic interactions at the single molecular scale. Our approach enables us to systematically vary hydrophobic and any other interaction type by utilizing peptide chemistry providing a strategic advancement to unravel molecular surface and soft matter interactions at the single molecular scale.
在软物质研究的所有领域中，基于分子相互作用对结构/性质关系的基本理解对于构建软材料靶向设计框架至关重要。然而，分子层面的情况往往难以确定，但对于理解众多不同的相互竞争作用（包括熵和协同性、水合作用以及软物质巨大的设计空间）却是必不可少的。在此，我们首次使用原子力显微镜对单个疏水分子之间的相互作用进行了定量表征，并证明单个分子疏水相互作用的自由能主要由最小相互作用疏水基团的面积决定。每个疏水单元的相互作用自由能为3 - 4 kT。此外，基于贝尔 - 埃文斯理论，我们发现疏水相互作用的过渡态相对于基态位于3 Å处。我们的结果为在单分子尺度上理解疏水相互作用的本质提供了一条新途径。我们的方法使我们能够通过利用肽化学系统地改变疏水及任何其他相互作用类型，为在单分子尺度上揭示分子表面和软物质相互作用提供了战略进展。
