4-aryl-3,5-bis(arylethynyl)aryl-4H-1,2,4-triazoles: Multitasking skeleton as a self-assembling unit

Abstract

The synthesis of a series of 4-aryl-3,5-bis(arylethynyl)aryl-4H-1,2,4-triazoles derivatives is reported and the influence exerted by peripheral substitution on the morphology of the aggregates generated from these 1,2,4-triazoles is investigated by SEM imaging. The presence of paraffinic side chains results in long fibrillar supramolecular structures, but unsubstituted triazoles self-assemble into thinner ribbons and needle-like aggregates. The crystals obtained from methoxy-substituted triazoles have been utilised to elaborate a model that helps to justify aggregation of the investigated 1,2,4-triazoles, in which the operation of arrays of C-H· π non-covalent interactions plays a significant role. The results presented herein demonstrate the ability of simple molecules to behave as multitasking scaffolds with different properties, depending on peripheral substitution. Thus, although 1,2,4-triazoles without long paraffinic side chains exhibit optical waveguiding behaviour, triazoles endowed with peripheral paraffinic side chains exhibit hexagonal columnar mesomorphism.