Three new beta-diketone-containing styrenic monomers and their polymers were synthesized. The phenol and naphthol groups, and the electron-donating N,N-dimethylaniline groups were covalently attached to the beta-diketone monomers at a designed position. The keto-enol tautomerism was characterized by H-1, C-13 NMR and UV-vis absorption spectroscopy. It was found that the beta-diketone monomers exist in three forms, i.e. two cis-enol forms and one keto form. Their relative contents were determined by NMR spectroscopy. The beta-diketone monomers bearing the phenol (1) and naphthol (2) groups display photoinduced enolization during UV irradiation due to the formation of intramolecular hydrogen bonds between the phenolic or naphtholic hydroxyl groups and the carbonyl groups. For their polymers and copolymers, however, photoinduced ketonization occurred during UV irradiation. The beta-diketone monomer bearing N,N-dimethylaniline group (3) is a novel charge transfer fluorophore, which can be potentially employed as a dual-purpose functional monomer. (c) 2006 Elsevier Ltd. All rights reserved.