Earring Porphyrins Bearing 1,9‐Di(pyrid‐2‐yl)dipyrromethene Unit and Their BODIPY Conjugates

Abstract

AbstractSuzuki–Miyaura coupling reactions of 2,18‐di(6‐bromopyrid‐2‐yl)‐substituted NiII porphyrin and 2,8,12,18‐tetrakis(6‐bromopyrid‐2‐yl)‐substituted NiII porphyrin with 1,9‐biboryl‐5‐mesityl dipyrromethene and subsequent oxidation with p‐chloranil gave single earring and double earring NiII porphyrins, respectively, which bear 1,9‐(dipyrid‐2‐yl)dipyrromethene unit. These NiII complexes were converted to free base porphyrins and then to ZnII porphyrins. Treatment of earring NiII and earring ZnII porphyrins with BF3⋅Et2O afforded the corresponding BODIPY (boron dipyrrin) conjugates and the ZnII porphyrin‐BODIPY conjugates were converted to free base porphyrin‐BODIPY conjugates. Bent structures of earring NiII porphyrins and the corresponding BODIPY conjugates have been revealed by X‐ray diffraction analysis. ZnII porphyrin‐BODIPYs show efficient fluorescence quenching, which is ascribed to fast intramolecular electron transfer from the ZnII porphyrin to the BODIPY moiety.