<i>meso</i>-Aryl Core-Modified Fused Sapphyrins: Syntheses and Structural Diversity

Two new, fused core-modified expanded porphyrins, sapphyrins <b>3</b> and <b>4</b>, were synthesized by a simple acid-catalyzed condensation of electron-rich and rigid precursor, dithienothiophene (DTT) diol, and core-modified tripyrrane. These sapphyrins exhibit structural diversity depending upon the heteroatom present in the macrocyclic framework, where the thiophene ring is inverted in <b>3</b>, while the selenophene ring in <b>4</b> exists in normal and inverted form in the free base and addition of two protons shifts the equilibrium to inverted form.