Abstract

The synthesis and magnetic properties of poly(2,2,4,4-tetramethyl-N-yloxy-1,4-dihydro-2H-3,1-benzoxazine-6,8-diyl-1,3-phenylene) (4) are described. Polyradical 4 was prepared by the Pd-catalyzed cross-coupling reaction of 6,8-dibromo-2,2,4,4-tetramethyl-1,4-dihydro-2H-3,1-benzoxazine and bis(trimethylene) 1,3-phenylenediboronate, followed by oxidation with m-chloroperoxybenzoic acid. The number average molecular weights of 4 determined by SEC (size exclusion chromatography) were ∼4120 (15 repeating units), and the spin concentrations determined by EPR were up to 0.75 spin per repeating unit. The EPR spectrum of 4 in a toluene glass matrix showed the ΔM_s = 2 forbidden transition at g = 4.0. A Curie plot of the ΔM_s = 2 signal intensity vs. 1/T gave a straight line, suggesting that the polyradical is in a triplet ground state or a nearly degenerate singlet–triplet state.