Dahan Elianne, Sundararajan Pudupadi R
Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada.
Soft Matter. 2014 Aug 7;10(29):5337-49. doi: 10.1039/c4sm00999a. Epub 2014 Jun 17.
Organogels with perylene derivatives and phthalocyanines reported in the literature so far involve self-assembly promoted by hydrogen bonds, in addition to aromatic and van der Waals interactions. Although the self assembly of these types of molecules without a hydrogen bonding group in the structure occurs in solution or during crystallization, the gelation studies reported so far incorporated a hydrogen bonding pair of the type N-H···O=C in the structure of the molecule. We present a case of thermo-reversible gelation without a hydrogen bonding group in the structure of (1) a coil-rod-coil molecule based on perylenetetracarboxylic diimide (PTCDI) and poly(dimethyl siloxane) (PDMS) and (2) a rod-coil molecule with perylene dicarboxylic imide (PDI) and PDMS. However IR spectroscopy shows the presence of multiple types of hydrogen bonding between the solvents and the gelator molecules. In addition, publications so far on gelation of perylene diimide based molecules involve groups attached to both imide nitrogens and with or without substitution in the bay position. We discuss here the gelation with a Mono-substituted perylene imide. The PDMS segment was attached to one side of PDI (Mono-PDMS) or to both imide nitrogens of PTCDI (Di-PDMS). The Mono-PDMS is an inverse macromolecular surfactant applicable to non-aqueous systems, and the Di-PDMS is a Gemini surfactant. The PDMS segment that we attached to PTCDI here is longer than most substituents used by other authors. These molecules gel propylamine, as well as mixed solvents of hexane-water and diisopropylamine-water. Both hexane and diisopropylamine dissolve Mono-PDMS and Di-PDMS at room temperature and addition of water results in precipitation. However, heating the solution to about 70 °C, adding water (5-15 wt%) and slowly cooling the solution, lead to gelation. The Di-PDMS forms fibers which are not flat but curved as an eaves trough. The Mono-PDMS forms hollow spheres. Although the Mono-PDMS and Di-PDMS are a homologous pair, blends of these do not show molecular intercalation during gelation, but self-sort. The fibers of Di-PDMS based gels encapsulate the spheres of the Mono-PDMS based gels.
迄今为止，文献中报道的含有苝衍生物和酞菁的有机凝胶除了芳香相互作用和范德华相互作用外，还涉及通过氢键促进的自组装。尽管这些在结构中没有氢键基团的分子类型的自组装发生在溶液中或结晶过程中，但迄今为止报道的凝胶化研究在分子结构中引入了N-H···O=C类型的氢键对。我们展示了一种热可逆凝胶化的情况，该凝胶化发生在以下两种分子的结构中，它们均没有氢键基团：（1）一种基于苝四羧酸二酰亚胺（PTCDI）和聚二甲基硅氧烷（PDMS）的线圈-棒-线圈分子；（2）一种含有苝二羧酸酰亚胺（PDI）和PDMS的棒-线圈分子。然而，红外光谱显示溶剂和凝胶剂分子之间存在多种类型的氢键。此外，迄今为止关于基于苝二酰亚胺分子的凝胶化的出版物涉及连接到两个酰亚胺氮上的基团，且在湾区有或没有取代基。我们在此讨论单取代苝酰亚胺的凝胶化。PDMS链段连接到PDI的一侧（单-PDMS）或PTCDI的两个酰亚胺氮上（双-PDMS）。单-PDMS是一种适用于非水体系的反相高分子表面活性剂，双-PDMS是一种双子表面活性剂。我们在此连接到PTCDI上的PDMS链段比其他作者使用的大多数取代基都要长。这些分子能使丙胺以及己烷-水和二异丙胺-水的混合溶剂凝胶化。己烷和二异丙胺在室温下都能溶解单-PDMS和双-PDMS，加入水会导致沉淀。然而，将溶液加热到约70°C，加入水（5-15 wt%）并缓慢冷却溶液，会导致凝胶化。双-PDMS形成的纤维不是扁平的，而是像檐槽一样弯曲。单-PDMS形成空心球体。尽管单-PDMS和双-PDMS是同系物对，但它们的混合物在凝胶化过程中不显示分子插层，而是自我分类。基于双-PDMS的凝胶纤维包裹着基于单-PDMS的凝胶球体。
