Syntheses and characteristics of push–pull derivatives for quadruply fused porphyrins

Abstract

“Push–pull” derivatives (2 – 4) of zinc(II) complexes having quadruply fused porphyrinato (QFP) ligands have been synthesized to elucidate the impact of the “push–pull” effects on the electronic structure of QFP. Each ZnQFP derivative of 2 – 4 has an electron-withdrawing group (EWG) such as nitro group and a methoxy group as an electron-donating group (EDG) at the diagonal positions of the molecule. Owing to the extended [Formula: see text]-conjugation of 2– 4 reaching to the substituted positions of the EWG and EDG, charge-transfer (CT) bands, which are sensitive to the solvent polarity, have been observed in the UV-vis spectra. In contrast, the corresponding “push–pull” derivatives of tetraphenylporphyrin, whose [Formula: see text]-conjugation is disconnected at the bonds between the meso-carbon and meso-aryl group, do not exhibit any CT transitions derived from the substituents.