A π-Conjugated System with Flexibility and Rigidity That Shows Environment-Dependent RGB Luminescence

We have designed and synthesized a pi-conjugated system that consists of a flexible and nonplanar pi joint and two emissive rigid and planar wings. This molecular system exhibits respectively red, green, and blue (RGB) emission from a single-component luminophore in different environments, namely in polymer matrix, in solution, and in crystals. The flexible unit gives rise to a dynamic conformational change in the excited state from a nonplanar V-shaped structure to a planar structure, leading to a dual fluorescence of blue and green colors. The rigid and planar moieties favor the formation of a two-fold pi-stacked array of the V-shaped molecules in the crystalline state, which produces a red excimer-like emission. These E RGB emissions are attained without changing the excitation energy.