Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke St. W., Montreal, Québec H4B 1R6, Canada.
Nanoscale. 2018 Aug 9;10(31):14993-15002. doi: 10.1039/c8nr04220a.
Controlled double-deck packing is an appealing means to expand upon conventional 2D self-assembly which is critical in crystal engineering, yet it is rare and poorly understood. Herein, we report the first systematic study of double-deck assembly in a series of alkylated aminoquinone derivatives at the liquid-solid interface. The competition between the fraction of alkyl chains adsorbed on the surface and the optimal conformation of the alkyl chains near the head group leads to a stepwise structural transformation ranging from complete double-deck packing to complete monolayer packing. Alkyl chains on the bottom or top layer of the double-deck assemblies were selectively visualized by carefully tuning the scanning tunneling microscopy settings. A method to easily identify mirror image domains was discovered based on the coincidence of domain boundaries with a graphite main axis. The effect of molecular symmetry and metal complexation on the formation of the double-deck assembly was also explored. Based on 2D crystal engineering principles, this bottom-up double-deck assembly can potentially provide an essential toehold for constructing precise 3D hierarchical structures.
双层控制包装是一种很有吸引力的方法，可以扩展传统的二维自组装，这在晶体工程中是至关重要的，但它很少见，也理解得不好。在此，我们报告了在一系列烷基化氨基醌衍生物在固-液界面的双层组装的第一个系统研究。吸附在表面的烷基链部分和靠近头基团的烷基链的最佳构象之间的竞争导致了从完全双层包装到完全单层包装的逐步结构转变。通过仔细调整扫描隧道显微镜设置，可以选择性地观察双层组装底部或顶部的烷基链。基于域边界与石墨主轴的重合，发现了一种易于识别镜像域的方法。还探索了分子对称性和金属络合对双层组装形成的影响。基于二维晶体工程原理，这种自下而上的双层组装有可能为构建精确的三维层次结构提供一个基本的立足点。
