Synthesis and characterization of new molecular complexation between free base meso-tetraarylporphyrins and nitrosonium ion as π-acceptor

Abstract

NOBF4 reacts with para-substituted meso-tetraarylporphyrins, H2t(4-Xp)p, at room temperature for formation of green molecular complexes, [H2t(4-Xp)p(NO)]BF4. Mole ratio for the porphyrins and nitrosonium ion in the molecular complexes was 1:1, [H2T(4-X)PP(NO)]BF4. FT-IR, UV–Vis, (1H and 13C) NMR spectral data, elemental analysis and molar conductivity indicated that NO+ (as electron acceptor) is bound to the lone electron pairs of the two pyrrolenine nitrogens in a side of the porphyrin plane. In these molecular complexes, two pyrrolic nitrogen atoms of the porphyrin core coordinate to the acceptor and two protons of the pyrrolic nitrogen atoms have been remained on the porphyrin macrocycles. Molecular complexation of meso-tetraarylporphyrins with NO+ produces a large downfield shift for the NH signal.