Synthesis and characterization of trans-di-(4-pyridyl)porphyrin dimers

Preparation and characterization of a small library of symmetric trans-di(4-pyridyl) porphyrin dimers, obtained by either Glaser–Hay or Sonogashira coupling reactions from appropriately prepared trans-di-4-pyridylporphyrin precursors, is presented. The porphyrin dimers are differentiated by a phenyl-alkynyl bridge of increasing length at one meso-position, while for all the derivatives the two remaining opposite meso-positions are tailored with a phenyl moiety bearing a short polyether chain. Coordination of the four pyridyl groups with appropriate metal fragments may be exploited to construct tubular hollow structures, with varied internal sizes, depending on the choice of the porphyrin dimer component.