Self-assembly of novel fluorescent silole derivatives into different supramolecular aggregates: fibre, liquid crystal and monolayer

Abstract

Two novel organogelators based on 2,3,4,5-tetraphenylsilole functionalized with long-chain alkoxydiacylamido platforms (1a and 1b) were synthesized. The silole derivatives induced gelation of only hydrocarbon solvents and showed aggregation-induced emission (AIE) in the gel state, in contrast to very weak emission in solution. The polarized optical microscopic (POM) and field emission scanning electron microscopy (FE-SEM) studies exhibited that the xerogels formed fibrous structures. Hydrogen bonding and π-stacking interactions were the main driving forces for the formation of organogels, based on the FT-IR and absorption investigations. Differential scanning calorimetry (DSC) and POM studies indicated that both compounds 1a and 1b exhibited stable liquid crystalline (LC) phases over a wide temperature range. It is interesting that uniform and well-ordered monolayers were also obtained for both compounds on the HOPG surface. The new silole derivatives are quite unique because they can self-assemble into one-dimensional (fibres), three-dimensional (liquid crystal) and even two-dimensional (molecular monolayer) aggregates.