LAUSR

Abstract Solid-state acidochromic (SSAC) molecules often exhibit dual-coloured rather than multi-coloured stimuli-responsive properties. To obtain the molecule possessing a multi-coloured emission switching based on one specific solid-state of a single molecule, a new D-π-A type 1,4-dihydropyridine derivative 4a containing barbituric acid and N , N -dimethylaniline unit, which contains multiple sites that can be combined with H + , is designed and synthesized. Compound 4a is confirmed to have twisted molecular conformation by crystallographic data and exhibits aggregation-induced emission characteristic. Upon the stimuli of acid-base system, 4a exhibits rare seven-coloured emission switching in solid-state. Another 1,4-dihydropyridine derivative 4b based on 1,3-dimethylbarbituric acid is synthesized for comparison. Compared with 4b which only displays three-coloured solid-state emission switching, 4a exhibits a more abundant colour change, which might be attributed that the nitrogen atoms on the N H bonds are also involved in the process of protonation and deprotonation, slowing down the transformation between D-π-A and A-π-A structures. The results provide a new idea for the development of multicolour SSAC materials.