Supramolecular Chemistry and Self-Assembly in Organic Materials Design

Organic materials naturally lend themselves to the crafting of structure and function using the strategies of self-assembly and supramolecular chemistry employed so effectively by biological systems. This perspective illustrates progress over the past two decades on self-assembly in materials chemistry through research on systems where function is directly linked to noncovalent interactions among molecules. The genesis of this approach in chemistry of materials involves the design of relatively simple structures using hydrogen bonding, pi-pi stacking, metal ligand interactions, electrostatic forces, strong dipole dipole association, hydrophobic forces, and steric repulsion. Gradually many new and exciting opportunities have emerged, such as supramolecular nanostructures that assemble into functional bulk materials and supramolecular polymers in which the motif of covalent connections among monomers is imitated by creating one-dimensional assemblies of an arbitrarily large set of molecules in both composition and size. Supramolecular polymers offer the opportunity to create structures that integrate unprecedented order in ID assemblies with interesting dynamics through bond reversibility. Other fascinating systems are those in which intermolecular interactions and other forces can be used to create the hierarchical and highly functional structures ubiquitous in biology, such as bone and muscle, in which different types of order exist within the same structure at different length scales. Directions that have a bright future include nonequilibrium dynamic materials with the capacity to be adaptive, self-repairing, chemically alterable, and even replicative all characteristics we see in living organic matter. Additional promising areas include 2D and 3D systems that are not necessarily classical crystals and the rational synthesis of functional organic inorganic hybrid materials. The most exciting aspect of self-assembly and supramolecular chemistry is their open ended nature, and these are two areas of chemistry for which many new principles will be established in this century.