One of his main achievements was to clarify the rationale of the photochromism observed in flavylium derivatives; Photochromism of the synthetic 4',7-dihydroxyflavylium chloride", J. Am. Chem. Soc. 1994 , 116 , 1249-1254. This was the beginning of a scientific journey that introduced in the scientific community flavylium derivatives as a new photochromic family. The work of almost two decades of research on this subject was recently summarized in the paper, F. Pina, M. J. Melo, C. A. T. Laia, A. J. Parola, J. C. Lima, “ Chemistry and Applications of Flavylium Compounds: a Handful of Colours” Chem. Soc. Rev. , 2012 , 41 , 869–908.
He and his group have shown that the flavylium based photochromic systems can operate in micelles, gels, zeolites, polymers and ionic liquids (F. Pina, J. C. Lima. A. J. Parola, C. A. M. Afonso, “Thermal and Photochemical Properties of 4’,7-dihydroxyflavylium in Water-Ionic Liquids Biphasic Systems: A Write-Read-Erase Molecular Switching System, Angew. Chem. Int. Ed. 2004, 43, 1525-1527).