Directly linked porphyrin arrays

The Ag I ‐promoted oxidative meso–meso coupling reaction of 5,15‐diaryl Zn II ‐porphyrin was serendipitously found in the course of our synthetic approaches towards photosynthetic reaction centers. Based on this reaction, a variety of directly linked and fused porphyrin arrays have been synthesized, including linear meso–meso‐ linked porphyrin arrays, windmill‐ and grid‐shaped porphyrin arrays, meso– β singly linked diporphyrins, β–β linked diporphyrins, meso– β doubly linked (fused) diporphyrins and oligoporphyrins, meso–meso β–β doubly linked (fused) diporphyrins, and meso–meso β–β–β–β triply linked (fused) diporphyrins. The meso–meso coupling reaction of 5,15‐diaryl Zn II ‐porphyrins is advantageous considering its high regioselectivity as well as its ease of extension to large porphyrin arrays as is demonstrated by the synthesis of a discrete meso–meso ‐linked 128‐mer and poly(5,15‐porphyrinylene). Finally, the oxidation of end‐phenyl capped meso–meso ‐linked zinc porphyrins with DDQ‐Sc(OTf) 3 gave π‐conjugated flat porphyrin tapes. To the best of our knowledge, the meso–meso linked 128‐mer is the longest man‐made discrete molecule, and the porphyrin tape 12‐mer is the most extensively conjugated porphyrin array, as evinced by the lowest electronic band peak at 3500 cm −1 . © 2003 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 3: 225–234; 2003: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.10062