Pillararene-Based Fluorescent Supramolecular Systems: The Key Role of Chain Length in Gelation.

Four supramolecular assemblies are fabricated from two pillararene tetramers with aggregation-induced emission properties (SH and LH) and two different lengths of neutral guests with three binding sites (arms) for pillararene cavities (SG and LG) through host-guest interactions, and their fluorescent behaviors in organic solvent are investigated. SG⊂SH exhibits the largest fluorescent enhancement in chloroform due to supramolecular assembly-induced emission enhancement, while only LG⊂LH turns into supramolecular gel with stimuli responsiveness owing to their most flexible arms.