Manifold dynamic non-covalent interactions for steering molecular assembly and cyclization
Shaotang Song, Lulu Wang, Jie Su, Zhen Xu, Chia-Hsiu Hsu, Chenqiang Hua, Pin Lyu, Jing Li, Xinnan Peng, Takahiro Kojima, Shunpei Nobusue, Mykola Telychko, Yi Zheng, Feng‐Chuan Chuang, Hiroshi Sakaguchi, Ming Wah Wong, Jiong Lu
Abstract
Deciphering rich non-covalent interactions that govern many chemical and biological processes is crucial for the design of drugs and controlling molecular assemblies and their chemical transformations. However, real-space characterization of these weak interactions in complex molecular architectures at the single bond level has been a longstanding challenge. Here, we employed bond-resolved scanning probe microscopy combined with an exhaustive structural search algorithm and quantum chemistry calculations to elucidate multiple non-covalent interactions that control the cohesive molecular clustering of well-designed precursor molecules and their chemical reactions. The presence of two flexible bromo-triphenyl moieties in the precursor leads to the assembly of distinct non-planar dimer and trimer clusters by manifold non-covalent interactions, including hydrogen bonding, halogen bonding, C-H⋯π and lone pair⋯π interactions. The dynamic nature of weak interactions allows for transforming dimers into energetically more favourable trimers as molecular density increases. The formation of trimers also facilitates thermally-triggered intermolecular Ullmann coupling reactions, while the disassembly of dimers favours intramolecular cyclization, as evidenced by bond-resolved imaging of metalorganic intermediates and final products. The richness of manifold non-covalent interactions offers unprecedented opportunities for controlling the assembly of complex molecular architectures and steering on-surface synthesis of quantum nanostructures.