CIDNP STUDY ON PORPHYRIN-PHOTOSENSITIZED REACTIONS WITH PHENOL AND QUINONE; DIMERIZATION OF 4-METHOXYPHENOL AND CROSS COUPLING OF BENZOQUINONE TO PORPHYRINS COVALENTLY LINKED WITH PHENOL GROUP

Article abstract of DOI:10.1016/S0040-4020(01)88075-3

Photoreactions of porphyrin (TPP) with phenol and/or quinone in non-polar benzene solution were studied mainly by the CIDNP technique.In the photoreaction of TPP with 4-methoxyphenol (1), CIDNP effects due to TPP^.- and 1^.+ were observed, while the generation of considerable amounts of free 4-methoxyphenoxyl radical was indicated by ESR and CIDNP in the three-component system involving TPP, 1, and p-benzoquinone (Q).Based on these results, two new photoreactions leading to permanent products were developed: (1) photosensitized dimerization of 1 and (2) photo-induced cross coupling of Q to porphyrins covalently linked with phenol group.The unique role of phenol in the photo-induced electron transfer reaction of TPP and Q in a non-polar solvent was discussed in terms of its dual function as both the proton and electron donor.