Study of spectral behaviour and optical properties of cis/trans-bis(N-methylpyridinium-4-yl)diphenyl porphyrin adsorbed on layered silicates

► Spectral behaviour of two porphyrins upon adsorption on clays was investigated. ► Impact was given on layer charge influence on the visible and fluorescence spectra. ► Adsorption of porphyrins led to spectral changes but preserved their photoactivity. ► Observed effects are attributed to “flattening” of the porphyrins and aggregation.