Synthesis of mono meso-pyridyl 21,23-dithiaporphyrins and unsymmetrical non-covalent porphyrin dimers

A new method has been developed to synthesize 21,23-dithiaporphyrins having one pyridyl group at the meso position. The method required easily available unknown precursors and the condensation resulted in mono meso-pyridyl 21,23-dithiaporphyrins as single products in 8–11% yield. Two of the three mono meso-pyridyl N2S2 porphyrins were used to synthesize non-covalent unsymmetrical porphyrin dimers containing one N2S2 and one N4 porphyrin cores.