MONOLAYER AND SPECTRAL PROPERTIES OF VARIOUS PORPHYRIN DERIVATIVES

The surface pressure and surface potential-area isotherms of various porphyrin derivatives have been studied at the air-water interface. The influence of some hydrophilic groups and of long hydrocarbon chains bonded to the porphyrin core on the monolayer and spectral properties is presented. It is shown that small changes in the molecular structure of porphyrins strongly affect the monomolecular and spectral properties of the porphyrin films. Moreover, the amplitude of the surface potential values is mainly governed by the mesomeric conjugation processes between the polar groups and the conjugated porphyrin ring. The spectral characteristics of most porphyrin derivatives have shown strong interactions within the porphyrin films. The presence of long hydrocarbon chains, which are not directly linked to the polar groups, and of flexible hydrophilic groups seem necessary to form a stable monomolecular film which is free of large aggregated structures. © 1991.