Synthesis and properties of 5-aza-15-thiaporphyrins

We have successfully prepared 5-aza-15-thiaporphyrin through nucleophilic sulfination of nitrogen-bridged dibromobisdipyrrin with sodium sulfide. X-ray diffraction analysis elucidated its structure in the solid state: two dipyrrin subunits were roughly coplanar around the sp 2 -hybridized meso-nitrogen. In contrast, they adopted a folded conformation around the meso-sulfur atom. Due to its relatively distorted structure, 5-aza-15-thiaporphyrin shows weak antiaromaticity in the magnetic criteria. The sulfur atom was oxidized with [Formula: see text]-chloroperbenzoic acid to provide 5-aza-15-thiaporphyrin [Formula: see text]-dioxide in good yield. While 5-aza-15-thiaporphyrin was non-emissive, its [Formula: see text]-dioxide exhibited fluorescence in solution.