Supramolecular assembly of leaf-like fluorescent tetraphenylethylene through polymer-directed inter-locking

We report an easy process for the fabrication of highly emissive tetraphenylethylene (TPE) with leaf-like architecture through a simple physical inter-locking of its rotating phenyl rings directed by polydimethylsiloxane (PDMS) film. The results reveal that the swelling and deswelling of PDMS film in TPE solution cause the emissive molecules to penetrate into the PDMS film and aggregate onto the film surface, respectively, which eventually emerge into a strongly fluorescent assembly. Mechanistically, when the PDMS deswells upon drying, the buckling effect of the material guides the adsorbed TPE molecules to assemble into closely packed architectures, as observed using a confocal microscopy. The results from the theoretical calculations suggest that the existence of through-space Ar-C···π electronic cloud interaction locks the rotation of phenyl rings in the assembled TPE architecture. This kind of electronic cloud delocalization starts off radiative decay process, endowing the material with a photophysical phenomenon of aggregation-induced emission (AIE). Interestingly, the developed assembly shows a sensory capability as confirmed by the progressive variation on the fluorescence of material as a function of mechanical strain applied. The current work offers an easy route to design supramolecular architectures possessing AIE attribute without introducing any chemical substituent.