Functional columnar assemblies

Abstract

Many functional materials rely on a well-organized internal structure for their output properties, and this makes them suitable for a variety of applications. Indeed, the control of the macroscopic molecular arrangement is essential for certain properties to manifest or to be enhanced. Our group has reported several examples of materials consisting of molecular building blocks encoded with functionality as well as with possibilities of self-organization. The final end is to create functional materials with well-defined molecular architectures that enable structural- and order-dependent properties. A particular approach is to exploit mesogenic driving forces to generate functional architectures by the self-organization of molecules into columnar mesophases. Furthermore, these mesophases are often based on molecules that can self-aggregate in solvents to afford functional gel materials with defined columnar molecular arrangements along their fibers. The work herein discussed will cover two types of functional columnar assemblies: i) Chiroptical supramolecular switches consisting on H-bonded complexes derived from melamine and carboxylic acids that self-organize into well-defined columnar mesophases, the supramolecular chirality of which can be tuned in a reversible manner by illumination with circularly polarized light. ii) Luminescent materials based on mesogenic molecules derived from a rigid π-conjugated core, 1,6-diphenyl-3-hexen-1,5-diyne. In bulk, the molecules self-organize into columnar mesophases that display luminescent as well as photoconducting properties. In solvents, the molecules give rise to aggregates that can immobilize the solvent affording luminescent organogels with enhanced emission