Foster William, Miyazawa Keisuke, Fukuma Takeshi, Kusumaatmaja Halim, Voϊtchovsky Kislon
Durham University, Physics Department, Durham DH1 3LE, UK.
Nanoscale. 2020 Mar 7;12(9):5452-5463. doi: 10.1039/c9nr09505e. Epub 2020 Feb 21.
Although common in nature, the self-assembly of small molecules at sold-liquid interfaces is difficult to control in artificial systems. The high mobility of dissolved small molecules limits their residence at the interface, typically restricting the self-assembly to systems under confinement or with mobile tethers between the molecules and the surface. Small hydrogen-bonding molecules can overcome these issues by exploiting group-effect stabilization to achieve non-tethered self-assembly at hydrophobic interfaces. Significantly, the weak molecular interactions with the solid makes it possible to influence the interfacial hydrogen bond network, potentially creating a wide variety of supramolecular structures. Here we investigate the nanoscale details of water and alcohols mixtures self-assembling at the interface with graphite through group-effect. We explore the interplay between inter-molecular and surface interactions by adding small amounts of foreign molecules able to interfere with the hydrogen bond network and systematically varying the length of the alcohol hydrocarbon chain. The resulting supramolecular structures forming at room temperature are then examined using atomic force microscopy with insights from computer simulations. We show that the group-based self-assembly approach investigated here is general and can be reproduced on other substrates such as molybdenum disulphide and graphene oxide, potentially making it relevant for a wide variety of systems.
尽管小分子在固液界面的自组装在自然界中很常见，但在人工系统中却难以控制。溶解的小分子的高迁移率限制了它们在界面处的停留，通常将自组装限制在受限系统或分子与表面之间有可移动连接链的系统中。小分子氢键分子可以通过利用基团效应稳定作用来克服这些问题，从而在疏水界面实现无连接链的自组装。值得注意的是，与固体的弱分子相互作用使得影响界面氢键网络成为可能，这有可能创造出各种各样的超分子结构。在这里，我们通过基团效应研究水和醇混合物在与石墨的界面处自组装的纳米级细节。我们通过添加少量能够干扰氢键网络的外来分子并系统地改变醇烃链的长度，来探索分子间相互作用和表面相互作用之间的相互影响。然后使用原子力显微镜并结合计算机模拟的见解，研究在室温下形成的超分子结构。我们表明，这里研究的基于基团的自组装方法具有通用性，并且可以在其他底物（如二硫化钼和氧化石墨烯）上重现，这可能使其适用于各种各样的系统。
