Preparation and Exchange Interaction of DPPH-Derived Polyradicals

Abstract

A series of 1,1′-(benzene-1,3-diyl)bis(1-phenyl-2-picrylhydrazine) derivatives was prepared and oxidized to generate the corresponding bis-DPPH diradicals. No triplet species was observed for the parent compound in the ESR. Incorporation of substituents in both the central benzene ring and the N-phenyl groups resulted in the detection of triplet diradicals. Especially, the diradical with Me and t-Bu groups on the central benzene and the N-phenyl rings, respectively, was successfully purified and isolated at O °C as a purple solid. Temperature-dependence of the intensity of the ESR signal showed that the isolated radical had a triplet ground state.

Key Words:

• exchange interaction
• DPPH
• esr
• triplet
• diradicals