MOLECULAR-COMPLEX FORMATION BETWEEN GADOLINIUM(III) TETRAPHENYLPORPHYRIN AND VITAMIN-E

The complex formation between Gd(III) tetraphenylporphyrin or free-bas e tetraphenylporphyrin and vitamin E have been studied by spectrophoto metric titration in chloroform and cyclohexane solutions. It has been shown that tetraphenylporphyrin and its gadolinium complex form 1:1 mo lecular complexes with vitamin E. The absorption spectra of titrated p orphyrins contain well defined isosbestic points. The equilibrium cons tants were found using curve fitting procedure. The observed interacti ons are stronger for metallated than for non-metallated porphyrin and in less polar than in polar solvents.