New AIE-active pyrimidine-based boronfluoride complexes with high solid-state emission and reversible mechanochromism luminescence behavior

A new family of pyrimidine-based BF₂ complexes (PB-1-4) with aggregation-induced emission (AIE) and mechanochromic luminescence properties were developed. These compounds exhibit intense fluorescence in their aggregation/solid-state resulting from their large Stokes shift and AIE. X-ray crystallographic analysis shows that the weak intermolecular interactions by fixing the molecular conformations of PB-1-4 are responsible for the intense fluorescence in solid-state. In addition to their pronounced AIE behaviour, PB-4 also exhibits a reversible chromic response to grinding, and a distinct red-shift of emission is observed. The high solid-state luminescence and grinding-stimuli response properties of these compounds make them potential candidates for smart materials.