Laboratory of Clean Energy Chemistry and Materials, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China.
Langmuir. 2013 May 7;29(18):5394-406. doi: 10.1021/la400202r. Epub 2013 Mar 12.
The engineering of single molecules into higher-order hierarchical assemblies is a current research focus in molecular materials chemistry. Molecules containing π-conjugated units are an important class of building blocks because their self-assembly is not only of fundamental interest, but also the key to fabricating functional systems for organic electronic and photovoltaic applications. Functionalizing the π-cores with "alkyl chains" is a common strategy in the molecular design that can give the system desirable properties, such as good solubility in organic solvents for solution processing. Moreover, the alkylated-π system can regulate the self-assembly behavior by fine-tuning the intermolecular forces. The optimally assembled structures can then exhibit advanced functions. However, while some general rules have been revealed, a comprehensive understanding of the function played by the attached alkyl chains is still lacking, and current methodology is system-specific in many cases. Better clarification of this issue requires contributions from carefully designed libraries of alkylated-π molecular systems in both self-assembly and nonassembly materialization strategies. Here, based on recent efforts toward this goal, we show the power of the alkyl chains in controlling the self-assembly of soft molecular materials and their resulting optoelectronic properties. The design of alkylated-C60 is selected from our recent research achievements, as the most attractive example of such alkylated-π systems. Some other closely related systems composed of alkyl chains and π-units are also reviewed to indicate the universality of the methodology. Finally, as a contrast to the self-assembled molecular materials, nonassembled, solvent-free, novel functional liquid materials are discussed. In doing so, a new journey toward the ultimate organic "soft" materials is introduced, based on alkylated-π molecular design.
将单个分子工程化为更高阶的分级组装是分子材料化学的当前研究重点。含有π共轭单元的分子是一类重要的构建块，因为它们的自组装不仅具有基础意义，而且是为有机电子和光伏应用制造功能系统的关键。在分子设计中，用“烷基链”官能化π核是一种常见策略，它可以赋予系统所需的性质，例如在有机溶剂中的良好溶解性，以进行溶液处理。此外，烷基化-π 系统可以通过精细调整分子间力来调节自组装行为。最优组装结构然后可以表现出先进的功能。然而，虽然已经揭示了一些一般规则，但对所附烷基链所起作用的全面理解仍然缺乏，并且在许多情况下，当前方法是针对特定系统的。更好地澄清这个问题需要在自组装和非组装材料化策略中精心设计的烷基化-π 分子系统文库中做出贡献。在这里，基于实现这一目标的最新努力，我们展示了烷基链在控制软分子材料自组装及其光电性能中的作用。选择 C60 的烷基化设计来自我们最近的研究成果，是此类烷基化-π 系统中最具吸引力的例子。还综述了一些由烷基链和π单元组成的其他密切相关的系统，以表明该方法的普遍性。最后，作为对自组装分子材料的对比，讨论了非组装、无溶剂的新型功能液体材料。这样，基于烷基化-π 分子设计，引入了通向终极有机“软”材料的新旅程。
