Preparation and characterization of novel DPPH-based diradicals

Article abstract of DOI:10.1016/S0040-4039(98)01227-1

A series of 1,1'(2,4-di-X-benzene-1,3-diyl)bis[1-(4-Y-phenyl)-2- picrylhydrazine]s were prepared an oxidized to generate the corresponding bis-DPPH diradicals. No triplet species was observed for the compounds with X = H in the ESR measurement. Modification of the central benzene ring (x = Me) and N-phenyl group (Y = OMe, P, t-Bu) allowed the detection of their triplet diradicals. Especially, the diradical with X = Me, Y = t-Bu was successfully purified, isolated at O ^aC as a purple solid, and was shown to be in a triplet ground state.