Chapter 2:Designing Soft Supramolecular Materials Using Intermolecular Interactions

Gelation of solvent(s) by low molecular weight gelators (LMWGs – small molecules having MW <3000) is a supramolecular phenomenon. Aggregation of 1D fibres resulting from supramolecular self-assembly of gelator molecules, giving rise to a 3D gel network known as self-assembled fibrillar networks (SAFiNs), is believed to be the key factor in gelation. Molecules containing metal atoms that take part in forming SAFiNs resulting in gels (known as metallogels) are also known. Solvent molecules are immobilized due to surface tension or capillary force actions within such 3D network resulting in gel. The wide range of applications that these soft materials offer attracted worldwide attention and there has been an upsurge in research activities involving LMWGs in recent years. Due to the lack of molecular level insights of the gelation mechanism, designing LMWGs is a daunting task and as a consequence, serendipity plays a prominent role in discovering most of the gelators and subsequent design of the next generation gelators are based on modifying the serendipitously-obtained parent gelator molecules. This chapter focuses on the designing aspects and applications of LMWGs, including metal-containing gelator molecules. It particularly covers the development of supramolecular synthon approach in the context of crystal engineering along with the other strategies to design such rewarding soft-materials.