Axial Ligand Exchange Reactions of <i>meso</i>-Aryl SubporphyrinsAxially Fluoro-Substituted Subporphyrin and a μ-Oxo Dimer and Trimer of Subporphyrins

High reactivity of the boron atom of meso-aryl subporphyrins enables the introduction of a broad range of functional groups to its axial position. Axially fluoro-substituted subporphyrins were easily synthesized upon treatment of axially hydroxyl-substituted subporphyrins with BF3·OEt2. Homogeneous μ-oxo dimers of subporphyrins were formed by heating monomers in the presence of triethylamine under a high vacuum. A heterogeneous subporphyrin−phthalocyanine−subporphyrin trimer was selectively formed from the respective monomers under similar reaction conditions. Structures of these molecules were elucidated by 1H NMR spectra and a single-crystal X-ray diffraction analysis, and the interactions between neighboring chromophores in the dimeric systems were estimated from absorption and magnetic circular dichroism spectra.