PROTONATION OF THE PORPHYRIN-KETONES AND THEIR COMPLEXES - VERIFICATION OF SPECTRAL FORMS AND MECHANISMS

Protomeric forms of the porphyrin-ketones (or oxo-chlorins) are invest igated by optical spectral methods. The main spectral forms of octaeth ylporphine-ketone and coproporphyrin-ketone tetramethyl ester appearin g in organic solvents in the presence of trifluoroacetic acid, in SDS micellar solution and in sulfuric acid, namely, the free base, monocat ion, dication and trication, are identified and described in detail. T heir mutual transformations are shown to proceed differently for the t wo dyes. The possibility of protonation of the macrocycle is also prov en for the porphyrin-ketone complexes. Two new spectral forms of plati num(II) and palladium(II) complexes of the porphyrin-ketones appearing in organic solvents on addition of TFA are described. Possible mechan isms of protonation, including formation of oxonium ions and carbocati ons, are discussed for these dyes. (C) 1997 Published by Elsevier Scie nce B.V.