Wu Yican, Li Jinxing, Yuan Yinlun, Dong Meiqiu, Zha Bao, Miao Xinrui, Hu Yi, Deng Wenli
College of Materials Science and Engineering, South China University of Technology, Wushan Road, Tianhe District, Guangzhou 510640, P. R. China.
Phys Chem Chem Phys. 2017 Jan 25;19(4):3143-3150. doi: 10.1039/c6cp08054e.
We design a bifunctional molecule (5-bromo-2-hexadecyloxy-benzoic acid, 5-BHBA) with a bromine atom and a carboxyl group and its two-dimensional self-assembly is experimentally and theoretically investigated by using scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. The supramolecular self-organization of 5-BHBA in two different solvents (1-octanoic acid and n-hexadecane) at the liquid-solid interface at different solution concentrations is obviously different due to the cooperative and competitive intermolecular halogen and hydrogen bonds. Three kinds of nanoarchitectures composed of dimers, trimers and tetramers are formed at the 1-octanoic acid/graphite interface based on -COOHHOOC-, triangular C[double bond, length as m-dash]OBrH-C, -BrO(H), BrBr, and OH interactions. Furthermore, by using n-hexadecane as the solvent, two kinds of self-assembled linear patterns can be observed due to the coadsorption, in which the dimers are formed by intermolecular -COOHHOOC- hydrogen bonds. The molecule-solvent and solvent-solvent van der Waals force and intermolecular hydrogen bonds dominate the formation of coadsorbed patterns. We propose that the cooperative and competitive halogen and hydrogen bonds are related to the polarity of the solvent and the type of molecule-solvent interaction. The intermolecular binding energy of different dimers and their stability are supported by theoretical calculations. The result provides a new and innovative insight to induce the 2D self-assembled nanostructures by halogen and hydrogen bonds at the liquid-solid interface.
我们设计了一种带有溴原子和羧基的双功能分子（5-溴-2-十六烷氧基苯甲酸，5-BHBA），并通过扫描隧道显微镜（STM）和密度泛函理论（DFT）计算，从实验和理论上研究了其二维自组装。由于分子间卤素键和氢键的协同与竞争作用，5-BHBA在两种不同溶剂（1-辛酸和正十六烷）中、在不同溶液浓度下于液-固界面处的超分子自组装明显不同。基于-COOHHOOC-、三角形C[双键，长度为m破折号]OBrH-C、-BrO(H)、BrBr和OH相互作用，在1-辛酸/石墨界面形成了由二聚体、三聚体和四聚体组成的三种纳米结构。此外，以正十六烷为溶剂时，由于共吸附可观察到两种自组装线性图案，其中二聚体由分子间-COOHHOOC-氢键形成。分子-溶剂和溶剂-溶剂范德华力以及分子间氢键主导了共吸附图案的形成。我们提出，卤素键和氢键的协同与竞争与溶剂的极性以及分子-溶剂相互作用的类型有关。理论计算支持了不同二聚体的分子间结合能及其稳定性。该结果为在液-固界面通过卤素键和氢键诱导二维自组装纳米结构提供了全新的见解。
