Synthesis and through-bond spin interaction of stable 1,3-phenylene linked poly(phenothiazine cation radical)

A 1,3-phenylene linked poly(phenothiazine cation radical) was synthesized and its through-bond spin interaction was investigated. Monomer and dimer models were also synthesized to investigate the behaviour of spins in poly(phenothiazine cation radical). X-Ray crystallographic analysis of the monomer model showed that it has a near-planar structure, which is favourable for spin interaction through pi-conjugation. MO calculation of the dimer model showed its exchange integral J (+31.4 K) is larger by about two times than that of diaminoxyl (+14.5 K) which is a dimer model of a polyradical studied previously. The spin state of poly( phenothiazine cation radical) was S = 2/2-3/2 in the ground state, indicating that, taking into account the average degree of polymerization (5-6) and the spin concentration (0.77 spins per repeating unit), 2-3 spins out of 4-5 spins per molecule were ferromagnetically aligned.