Molecular Selective Ordinal Stacking And Their Hierarchical Structures

The functions of biological macromolecular (e.g. protein) are not only related to its component, the covalent molecular structure, but are decided to a large extent by the high-level structure formed by its assembly via non-covalent interaction. Similarly, as for those functional materials, their functions, to a great degree, depend on the high-level structure of its assembly. With people understanding more about life and pursuing the function of materials, more attention is paid to the understandings and designs of the high-level structure. Therefore, non-covalent synthesis gradually becomes the focus of chemosynthesis. How to probe and discuss the molecular behavior by making use of the intermolecular weak interactions to rational design, realize the ordinal stacking between molecules and establish hierarchical structures is one of the most difficult issues in this century's chemical research. At the same time, as for crystal engineering, another hang-up is about how to regulate intermolecular weak interactions so as to predict and design the packing and assembly of the high-level structure directly according to the covalent molecular structure.In the researches of this dissertation, we utilized diethoxycarbonyl glycoluril as the basic molecular component and modified it rationally and functionally. We obtained three series with thirty-two new supramolecular building blocks. In addition, in order to have a systematical research about the weak intermolecular interaction and selective stacking, we purposefully gave these compounds a systematical cultivation of single crystal and got totally twenty-five systematic structures of single crystal.The result of the initial research showed that molecular clips bearing one 1,4-dimethoxyxylylene sidewall could form cleft-cleft dimeric structure. Based on such a basic assembly, we designed and synthesized the chiral molecular clip (±)-3U-R-OMe. Meanwhile, we also penetrated the characteristic of the lack of symmetry and site complementary of interactions for molecular clip with a rigid framework, and used molecular clip serve as a kind of especial supramolecular synthon to form the secondary structure driven by weak C-H…O andÏ€-Ï€interactions, while this secondary structure could be further assembled to get a tertiary structure driven by H-bonded interaction of the functional group (e.g. (±)-3U-NH₂-OMe, (±)-3U-H-OMe) or metal-coordination interaction (e.g. (±)-3U-Py-OMe)). The whole process represented a rational design and synthesis of high-level assembly structure similar to the hierarchical structure of protein. At the same time, we systematically analyzed all the possible dimeric modes of the chiral molecular clip (±)-3U-R-0Me and researched its driving force during the formation of dimeric structure. On its basis, we introduced the functional group with competitive interaction into this kind of molecular clip. It was showed that the dimeric mode of molecules did change due to the competitive interaction, which proved that the self-assembly of complex systems would also choose relatively competitive interaction to drive.Besides, we also systematically did researches about (±)-2U-R glycoluril system. The former reports about the compounds with similar structures were invariably the researches of self-assembly's commonness, but we studied the diversity of structures of such compounds during the self-assembly. As it was shown, the chirality of molecules and the nature of functional group would influence molecular self-assembly and the formation of supramolecular polymer, and we also found the solvent effect and polymorph. For example, the compound (±)-2U-CCH formed a twelve-member ring driven by DMSO-assisted H-bonded interactions and the compound (±)-2U-Ph-OMe formed a polymer chain structure with the help of MeOH or H₂O molecules.Finally, we also designed and synthesized isomeric molecular clip (±)-3U-R-CT, 3U-R-CC and systematically discussed the impact of the functional group's location on molecular self-assembly. As the research showed, it was easy for CC molecule to form cleft-cleft dimeric structure, while it was impossible for CT molecule due to the repulsion of substituent groups, rather, it inclined to form the outward packing for the sidewalls. This research also showed that the nature of functional groups played a decisive role in the form of molecular self-assembly, for instance, molecular clip 3U-Ph-OMe-CC, it could form a self-recognition supramolecular polymer driven by the OCH₃…O= C interactions.