Molecular “Hozo”: Thermally Stable Yet Conformationally Flexible Self-Assemblies Driven by Tight Molecular Meshing

• Published in: Bulletin of the Chemical Society of Japan 2021-10, Vol.94 (10), p.2329-2341
• Main Authors: Zhan, Yi-Yang, Hiraoka, Shuichi
• Format: Article
• Language: English
• Subjects: Assemblies; Bonding strength; Cations; Hydrogen bonds; Hydrophobic surfaces; Hydrophobicity; Masterpiece Materials with Functional Excellence; Meshing; Molecular interactions; Self-assembly; Thermal stability; Water chemistry
• ISSN: 0009-2673; 1348-0634
• DOI: 10.1246/bcsj.20210228

Various noncovalent molecular interactions have been employed as driving forces to construct well-defined discrete self-assemblies. Among them, coordination and hydrogen bonds are widely used due to their high directionality and appropriate bond strength. However, the utilization of nondirectional, week molecular interactions for this purpose still presents a key challenge in supramolecular self-assembly. To tackle this critical issue, we presented a novel design concept, molecular “Hozo”, that the components with large, indented complementary hydrophobic surfaces tightly mesh with each other driven by the hydrophobic effect in water. Based on this concept, we developed a series of water-soluble cube-shaped molecular assemblies, i.e., nanocubes, composed of six molecules of identical gear-shaped amphiphiles (GSAs) with the aid of van der Waals (vdW) and cation-π interactions as well as the hydrophobic effect. The nanocubes exhibit unique properties derived from molecular meshing of the building blocks, such as high thermal stability yet as high conformational flexibility as biological molecules and emission whose intensity is affected by the structural change of the nanocube.