College of Material Science and Engineering & State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Chemistry & biology Engineering, Donghua University, Shanghai 201620, China.
Phys Chem Chem Phys. 2013 Dec 21;15(47):20753-63. doi: 10.1039/c3cp52864b. Epub 2013 Nov 6.
The substituent group and hydrogen bonds play important roles in supramolecular self-assembly. To exploit the influential mechanism of hydrogen bonds during the dipole-dipole induced supramolecular self-assembly, some rigid azobenzene molecules with different electronegativity and hydrogen bonding capabilities were identified and designed. Different regular-shaped architectures were constructed via a simple solution process under mild conditions. Both experimental results and density functional theory calculations show that weak π-π stacking interactions lead to thick and short nanocylinders, strong dipole-dipole interactions and dipole induced π-π stacking lead to long and thin nanorods, appropriate hydrogen bonds consolidate the dipole-dipole interactions and dipole induced π-π stacking, forming thin nanosheets, while excessive hydrogen bonds in azobenzene would ruin the regular-shaped structures, giving irregular and stochastic aggregates. Namely there exists a certain hydrogen bond saturation effect in generating azobenzene nanostructures driven by dipole-dipole interactions. The results indicate that the morphologies of organic materials with azobenzene structures can be effectively controlled through rational molecular design by way of introducing appropriate dipole and hydrogen bonds.
取代基和氢键在超分子自组装中起着重要作用。为了利用氢键在偶极-偶极诱导的超分子自组装过程中的影响机制，我们鉴定并设计了一些具有不同电负性和氢键能力的刚性偶氮苯分子。通过简单的溶液处理在温和条件下构建了不同的规则形状的结构。实验结果和密度泛函理论计算都表明，弱的π-π堆积相互作用导致厚而短的纳米圆柱，强的偶极-偶极相互作用和偶极诱导的π-π堆积导致长而细的纳米棒，适当的氢键巩固了偶极-偶极相互作用和偶极诱导的π-π堆积，形成薄的纳米片，而过多的偶氮苯中的氢键会破坏规则的结构，形成不规则和随机的聚集体。即在偶极-偶极相互作用驱动的偶氮苯纳米结构的生成中存在一定的氢键饱和效应。结果表明，通过引入适当的偶极和氢键，通过合理的分子设计可以有效地控制具有偶氮苯结构的有机材料的形态。
