PORPHYRIN-QUINONE CYCLOPHANES WITH GRADUALLY VARIED ACCEPTOR STRENGTH - SYNTHESES AND CHARACTERIZATIONS

For studying intramolecular electron-transfer reactions, three groups of double- and single-bridged porphyrin-quinone cyclophanes 1 - 4, 5 - 9, and 11 - 14, resp., with gradual variation of quinone acceptor strengths were synthesized. As key intermediates for building up the porphyrin-cyclophane skeleton the correspondingly 3,6-substituted 1,4-bis[4-(2-formylphenyl)butyl]-2,5-dimethoxybenzenes 15 - 20 were synthesized. Condensation with pyrrole yielded the doubly bridged porphyrin cyclophanes 42--45; via the bis(dipyrrolylmethyl) derivatives 46 - 51 and 64 - 67 the single-bridged porphyrin cyclophanes 58 - 63 and 72 - 75 were obtained by acidic condensation with triethyl formate. Cleavage of the methoxy groups and oxidation yielded the corresponding porphyrin-quinone systems. Some magnesium and zinc complexes of these cyclophanes are described. Spectroscopic data (MS, H-1 NMR) are reported in support of the proposed structures.