Department of Polymer Science, College of Polymer Science and Polymer Engineering, University of Akron, Akron, OH 44325, USA.
Department of Chemistry and Biotechnology, School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Science. 2015 Apr 24;348(6233):424-8. doi: 10.1126/science.aaa2421.
Self-assembly of rigid building blocks with explicit shape and symmetry is substantially influenced by the geometric factors and remains largely unexplored. We report the selective assembly behaviors of a class of precisely defined, nanosized giant tetrahedra constructed by placing different polyhedral oligomeric silsesquioxane (POSS) molecular nanoparticles at the vertices of a rigid tetrahedral framework. Designed symmetry breaking of these giant tetrahedra introduces precise positional interactions and results in diverse selectively assembled, highly ordered supramolecular lattices including a Frank-Kasper A15 phase, which resembles the essential structural features of certain metal alloys but at a larger length scale. These results demonstrate the power of persistent molecular geometry with balanced enthalpy and entropy in creating thermodynamically stable supramolecular lattices with properties distinct from those of other self-assembling soft materials.
具有明确形状和对称性的刚性构建块的自组装受到几何因素的极大影响，在很大程度上仍未得到探索。我们报告了一类精确定义的纳米级巨型四面体的选择性组装行为，这些巨型四面体由刚性四面体框架顶点处的不同多面体低聚倍半硅氧烷（POSS）分子纳米颗粒构建而成。通过对这些巨型四面体进行对称性破坏，可以引入精确的位置相互作用，并导致多种选择性组装的、高度有序的超分子晶格，包括弗兰克-卡珀 A15 相，其类似于某些金属合金的基本结构特征，但在更大的尺度上。这些结果表明，持久的分子几何形状具有平衡的焓和熵，在创造具有不同于其他自组装软物质的特性的热力学稳定超分子晶格方面具有强大的功能。
