Search

The use of protonation to switch nonaromatic expanded porphyrins to their corresponding anti-aromatic forms has not been widely explored. Here, we show that free-base pyriamethyrin and dipyriamethyrin display nonaromatic character, as inferred from NMR spectroscopic analyses, their optical properties, and theoretical calculations. Addition of two protons extends the π – conjugation of these amethyrin analogues and yields formally anti-aromatic systems. [ABSTRACT FROM AUTHOR]

The reaction between amethyrin and non-aqueous uranyl silylamide (UO2[N(SiMe3)2]2) under anaerobic conditions affords a bench-stable uranyl complex. UV-vis spectroscopy, cyclic voltammetry, as well as proton NMR spectroscopic analyses provide support for the conclusion that all six pyrrole subunits participate in coordination of the uranyl dication and that, upon complexation, the amethyrin-core undergoes a 2-electron oxidation to yield a formal 22 π-electron aromatic species. [ABSTRACT FROM AUTHOR]

The reaction between dipyriamethyrin and copper(II) acetate [Cu(OAc)2] afforded what is, to our knowledge, the first transition metal-dipyriamethyrin complex. Molecular and electronic characterization of this binuclear Cu(II) complex via EPR, UV-vis, and single crystal X-ray diffraction analysis revealed marked differences between the present constructs and previously reported binuclear copper(II) hexaphyrin species. UV-vis titration analyses provided evidence for a homotropic positive allosteric effect, wherein the binuclear species is formed without significant intermediacy of a monomeric complex. [ABSTRACT FROM AUTHOR]