The stepwise syntheses and characterization of a series of symmetrical and unsymmetrical bisporphyrins, bischlorins, and biscorroles, and of porphyrin−chlorin and porphyrin−corrole dyads possessing ethylene, phenyl, and stilbene linking units are described. The methodology for synthesis of 10-substituted corroles 2 and their cobalt complexes 9 via a,c-biladiene salts 1 was first developed, and then extended to provide biscorroles (e.g., 4 and 5) linked through the 10-positions with phenyl linker units. Using a similar methodology, phenyl-linked corrole−porphyrin dyads 28 and 30 were also prepared. By way of intermediate phenyl-linked unsymmetrical bisdipyrromethanes, a completely unsymmetrical heterobimetallic bisporphyrin system, 45, was synthesized. Low-valent titanium coupling (McMurry) reactions were used to prepared stilbene-linked bisdipyrromethanes (e.g., 46) which were subsequently transformed into stilbene-linked bisporphyrins (e.g., 48). McMurry cross-coupling reactions of porphyrins bearing p-formylphenyl substituents also afforded an unsymmetrically substituted bisporphyrinylstilbene, 60, as well as the corresponding homodimers 56 and 59. Likewise, McMurry cross-coupling of a p-formylphenyl-substituted porphyrin, 62, with a formylchlorin, 63, afforded a stilbene-linked bisporphyrin, 64, a bischlorin, 66, and a novel porphyrin−chlorin heterodimer, 65. All novel products were characterized by 1H NMR, UV−vis, and mass spectroscopy and elemental analysis. X-ray structural information was also obtained for the zinc/nickel bisporphyrin 45 and for the bis-nickel porphyrin−chlorin 65.

No abstract

TiCl3‐induced coupling of meso‐forrnylporphyrins provides cofacial porphyrin dimers such as 1 (M  Cu, Ni) with bridging cis‐CHCH units. These compounds show strong interactions between the porphyrin rings; in the case of M  Ni, the dimer can be easily transformed into the corresponding trans isomer. Similar reactions with β‐formyl‐porphyrins lead to a third type of dimer, a skewed hydroxymethylene‐bridged bisporphyrin. These dimeric compounds are models for the photosynthetic reaction center and should facilitate studies on the influence of the dimer geometry on the photophysical properties.

No abstract

The first stepwise syntheses of unsymmetrically substituted 1 ,I 9-dibromo-a,c-biladienes, e.g. 3c, via the so-called tripyrrene route', and their facile conversion into biliverdins (bilin-I ,I 9-diones), e.g. 4c, are described; this methodology is also adapted for the preparation of symmetrical biliverdins 4a, as well as corroles 5 and azaporphyrins 6.