Graduate School of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
ACS Nano. 2020 Oct 27;14(10):13294-13303. doi: 10.1021/acsnano.0c05093. Epub 2020 Oct 5.
Molecular behavior and functionality are affected by their prevailing immediate environment. Molecular machines function according to conformational variations and have been studied largely in solution states. In order to access more highly complex functional molecular machines, it is necessary to analyze and control them in various environments. We have designed and synthesized a bisbinaphthyldurene (BBD) molecule that has two binaphthyl groups connected through a central durene moiety, allowing for the formation of several conformers. In density functional theory (DFT) calculations, BBD has five major conformers, denoted -1/-2/-1/-2/. It has been demonstrated that BBD exhibits different conformations in solution (-1 and -1) than on a gold surface ( dimer and ). In this work, the ratio of BBD conformations has been controlled in mixed monolayers with several different lipids at an air-water interface in order to compare conformational activity under different conditions. The conformations of BBD in transferred films obtained by using Langmuir-Blodgett techniques were estimated from circular dichroism spectra and DFT calculations. It has been found that the conformation of BBD in the mixed monolayer depends on its aggregated state, which has been controlled here by the mechanical properties and miscibility. In mixed monolayers with "hard" lipids having less miscibility with BBD as well as in cast film, BBD is self-aggregated and mostly forms stable -1 and -1 conformations, while unstable -2 and -2 conformers dominated in the more dispersed states involving "soft" lipids, which show good miscibility with BBD. Conformational changes in BBD are due to the formation of different aggregated states in each mixed monolayer according to the miscibility. Overall, BBD molecular conformations (and the resulting spectra) could be tuned by controlling the environment whether in solution, on a solid substrate, or in an admixture with lipids at the air-water interface.
分子的行为和功能受其所处的环境影响。分子机器根据构象变化发挥功能，其研究主要在溶液状态下进行。为了研究更复杂的功能分子机器，需要在各种环境中对其进行分析和控制。我们设计并合成了一种双联萘二芴（BBD）分子，该分子通过中央芴部分连接两个联萘基，形成了几种构象。在密度泛函理论（DFT）计算中，BBD 有五个主要构象，分别表示为-1/-2/-1/-2/。研究表明，BBD 在溶液中（-1 和-1）和在金表面（二聚体和）呈现出不同的构象。在这项工作中，我们通过在空气-水界面的混合单层中控制几种不同的脂质，控制了 BBD 构象的比例，以比较不同条件下的构象活性。通过使用 Langmuir-Blodgett 技术获得的转移膜中 BBD 的构象，是根据圆二色性光谱和 DFT 计算来估算的。研究发现，BBD 在混合单层中的构象取决于其聚集状态，而聚集状态又由机械性能和混溶性控制。在与 BBD 混溶性较差的“硬”脂质的混合单层以及在浇铸膜中，BBD 自聚集并主要形成稳定的-1 和-1 构象，而在涉及与 BBD 混溶性良好的“软”脂质的更分散状态下，不稳定的-2 和-2 构象占主导地位。BBD 的构象变化是由于在每个混合单层中根据混溶性形成了不同的聚集状态。总的来说，可以通过控制环境（无论是在溶液中、在固体基底上还是在空气-水界面与脂质的混合物中）来调节 BBD 分子的构象（以及由此产生的光谱）。
