Alteration of optical anisotropy by adsorption of volatile molecules on ordered metalloporphyrins layers

Reflectance anisotropy spectra of porphyrin thin films (30 monolayers) show a permanent change in their line shape when porphyrins are exposed to some specific analytes (e. g., amines). From this experimental evidence, we concluded that a molecular package adjustment occurred in the film upon interaction with the volatile compound, most likely in the outermost layers. This result is of paramount importance for the consequent application of these films in optical gas-sensors. Consequently, this system could be used as a prototype for optical gas-sensing of aggressive analytes or, more ambitiously, to investigate the porphyrin-analyte interaction.