meso-Aryl substituted rubyrin and its higher homologues: structural characterization and chemical properties

meso-Aryl substituted rubyrin (26]hexaphyrin(1.1.0.1.1.0)) 2 and a series of rubyrin-type large expanded porphyrins were obtained from a facile one-pot oxidative coupling reaction of meso-pentafluorophenyl substituted tripyrrane 1. The structures of two of the resulting products were determined by single-crystal X-ray diffraction analysis. Whereas 52]dodecaphyrin(1.1.0.1.1.0.1.1.0.1.1.0) 4 takes a symmetric helical conformation, the larger species, 62]pentadecaphyrin(1.1.0.1.1.0.1.1.0.1.1.0.1.1.0) 5, adopts a nonsymmetric distorted conformation in the solid state that contains an intramolecular helical structure. The ability of rubyrin 2 to act as an anion receptor in its diprotonated form (2(.)2H(+)) was demonstrated in methanolic solutions. Oxidation of 2 with MnO(2) gave 24]rubyrin 6, a species that displays antiaromatic characteristics. 26]Rubyrin 2 and 24]rubyrin 6 both underwent metallation when reacted with Zn(OAc)(2) to give the corresponding bis-zinc(II) complexes 7 and 8 quantitatively without engendering a change in the oxidation state of the ligands. As a result, complexes 7 and 8 exhibit aromatic and antiaromatic character, respectively. NICS calculation on these compounds also supported aromaticity of 2 and 7, and antiaromaticity of 6 and 8.