Centre Energie, Materiaux et Telecommunications, Institut National de la Recherche Scientifique, 1650 Boulevard Lionel-Boulet, Varennes, QC, Canada J3X 1S2.
Nanoscale. 2019 Mar 21;11(12):5422-5428. doi: 10.1039/c8nr09810g.
Investigating two-dimensional (2D) self-assembled structures of biological monomers governed by intermolecular interactions is a prerequisite to understand the self-assembly of more complex biomolecular systems. 5,6-Dihydroxyindole carboxylic acid (DHICA) is one of the building blocks of eumelanin - an irregular heteropolymer and the most common form of melanin which has potential applications in organic electronics and bioelectronics. By means of scanning tunneling microscopy, density functional theory and Monte Carlo calculations, we investigate DHICA molecular configurations and interactions underlying the multiple 2D patterns formed on Au(111). While DHICA self-assembled molecular networks (SAMNs) are dominated by the hydrogen bonding of carboxylic acid dimers, a variety of 2D architectures are formed due to the multiple weak interactions of the catechol group. The hydroxyl group also allows for redox reactions, caused by oxidation via O2 exposure, resulting in molecular rearrangement. The susceptibility of the molecules to oxidation is affected by their SAMNs architectures, giving insights on the reactivity of indoles as well as highlighting non-covalent assembly as an approach to guide selective oxidation reactions.
研究受分子间相互作用控制的生物单体的二维（2D）自组装结构是理解更复杂生物分子系统自组装的前提。5,6-二羟基吲哚羧酸（DHICA）是真黑素的结构单元之一——一种不规则的杂多聚物，也是最常见的黑色素形式，在有机电子学和生物电子学中有潜在的应用。通过扫描隧道显微镜、密度泛函理论和蒙特卡罗计算，我们研究了 DHICA 分子在 Au(111)上形成的多种二维图案的分子构型和相互作用。虽然 DHICA 自组装分子网络（SAMNs）主要由羧酸二聚体的氢键控制，但由于儿茶酚基团的多种弱相互作用，形成了多种二维结构。羟基还允许通过暴露于 O2 进行氧化引起的氧化还原反应，导致分子重排。分子对氧化的敏感性受其 SAMNs 结构的影响，这为吲哚的反应性提供了深入了解，并强调了非共价组装作为指导选择性氧化反应的一种方法。
