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The interaction of some aromatic amines such as o-aminobenzoic acid, methyl anthranilate, and 0m-p-toluidines with very dilute solutions of ethylene trithiocarbonate (ETTC) have been studied employing steady-state fluorescence quenching measurements and time-correlated single-photon counting spectroscopy. Electronic excitation transfer and static quenching is assumed to describe the higher bimolecular rate constants for the toluidine-ETTC systems. In addition, the possible interpretation of the quenching mechanism is discussed in relation to the electron-transfer between colliding species.

Porphyrin and phthalocyanine, because of their stability, planarity, suitable redox potential and absorption characteristics have been widely used to modify electrodes for photoelectrochemical conversion of solar energy. It has been observed that electropolymerisation technique is a very convenient method for coating an electrode which generates reproducible photovoltage and photocurrent as well as good fill factor when set up in a suitable photoelectrochemical device. In our previous work Rohatgi-Mukherjee 1988, 1992) using vinyl substituted porphyrin, good photovoltage and fill factor could be obtained though photocurrent generation was not very efficient. With the objective of improving the performance of the photoelectrode, electropolymerisation of amino and hydroxy substituted tetraphenylporphyrin has been attempted. Amino groups are known to give highly conducting polymer films and when attached to photoactive porphyrin it is expected to improve photocurrent production. Aminoporphyrin polymerised from methylene chloride solution by oxidative scanning at a platinum electrode shows characteristic cyclic voltammograms when scanned in CH2CI2-TBAP solution. Similar CV are produced when solutions contain metalloaminoporphyrins. The absorption spectra of the film formed on a transparent SnO2 electrode showed a characteristic soret absorption band with red shift relative to the solution due to polymerisation. No film formation is observed when a methylene chloride solution of Zn-complex of aminophenylporphyrin is cycled to 0.9 V, just beyond the porphyrin radical cation oxidation wave, but extending the sweep to 1.4 V leads to coating formation. Thus the mechanism of electropolymerisation for aminophenylporphyrins is different from that of vinyl polymerisation.

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