Supramolecular layer: Toward resolving the conflict between rigidity and flexibility in design of pressure-enhanced luminescence molecule

The design of pressure-related aggregation-induced emission (PAIE) molecular structure has to find a compromise between rigidity and flexibility. In order to resolve the contradiction, here a supramolecular layer is constructed by employing three components containing 1,2-bis[4-(3-sulfonatopropoxyl)-phenyl]-1,2-diphenylethene sodium salt (BSTPE), layered double hydroxides (LDHs) and poly(acrylic acid) (PAA). Mechanism shows: 1) rigid LDH nanosheet not only can avoid interpenetration between adjacent layers of PAA films, but assistants the formation of aggregation-induced emission (AIE) molecular layer; 2) PAA can wrap the BSTPE molecules and provide sufficient free space for rearrangement of AIE molecules during the pressure response owing to its high flexibility. The as-constructed (BSTPE@PAA/LDH)n supramolecular layer film shows an excellent anisotropic structure and emission performances, accompanied by high stability (photo, adhesion and storage). Interestingly, the pressure-related luminescence behavior of the film at the MPa level. The gradually increased intensity with the increase of pressure is attributed to the tight and order packing of BSTPE in interlayer of LDHs by the external pressure. This work provides a design rule for the construction of pressure-sensitive supramolecular layer, which resolves the conflict between rigidity and flexibility in the molecule design of pressure-enhanced emission materials.