Adhikari Bimalendu, Lin Xu, Yamauchi Mitsuaki, Ouchi Hayato, Aratsu Keisuke, Yagai Shiki
Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
Chem Commun (Camb). 2017 Aug 29;53(70):9663-9683. doi: 10.1039/c7cc04172a.
Hydrogen-bonded supermacrocycles (rosettes) are attractive disk-shaped noncovalent synthons for extended functional columnar nanoassemblies. They can serve not only as noncovalent monomer units for supramolecular polymers and discrete oligomers in a dilute solution but also as constituent entities for soft matters such as gels and lyotropic/thermotropic liquid crystals. However, what are the merits of using supramolecular rosettes instead of using expanded π-conjugated covalent molecules? This review covers the self-assembly of photochemically and electrochemically active π-conjugated molecules through the formation of supramolecular rosettes via directional complementary multiple hydrogen-bonding interactions. These rosettes comprising π-conjugated covalent functional units stack into columnar nanoassemblies with unique structures and properties. By overviewing the design principle, characterization, and properties and functionalities of various examples, we illustrate the merits of utilizing rosette motifs. Basically, one can easily access a well-defined expanded π-surface composed of multi-chromophoric systems, which can ultimately afford stable extended nanoassemblies even in a dilute solution due to the higher association constants of supermacrocyclized π-systems. Importantly, these columnar nanoassemblies exhibit unique features in self-assembly processes, chiroptical, photophysical and electrochemical properties, nanoscale morphologies, and bulk properties. Moreover, the stimuli responsiveness of individual building blocks can be amplified to a greater extent by exploiting rosette intermediates to organize them into one-dimensional columnar structures. In the latter parts of the review, we also highlight the application of rosettes in supramolecular polymer systems, photovoltaic devices, and others.
氢键连接的超大环（玫瑰花结）是用于扩展功能柱状纳米组装体的有吸引力的盘状非共价合成子。它们不仅可以作为稀溶液中超分子聚合物和离散低聚物的非共价单体单元，还可以作为诸如凝胶和溶致/热致液晶等软物质的组成实体。然而，使用超分子玫瑰花结而不是使用扩展的π共轭共价分子有哪些优点呢？本综述涵盖了通过定向互补多重氢键相互作用形成超分子玫瑰花结，使光化学和电化学活性π共轭分子进行自组装。这些由π共轭共价功能单元组成的玫瑰花结堆叠成具有独特结构和性质的柱状纳米组装体。通过概述各种实例的设计原理、表征、性质和功能，我们阐述了利用玫瑰花结基序的优点。基本上，人们可以轻松获得由多发色团系统组成的定义明确的扩展π表面，由于超大环化π系统具有更高的缔合常数，即使在稀溶液中也能最终形成稳定的扩展纳米组装体。重要的是，这些柱状纳米组装体在自组装过程、手性光学、光物理和电化学性质、纳米级形态以及本体性质方面表现出独特的特征。此外，通过利用玫瑰花结中间体将单个构建块组织成一维柱状结构，可以在更大程度上放大它们的刺激响应性。在综述的后半部分，我们还强调了玫瑰花结在超分子聚合物系统、光伏器件等方面的应用。
