Ferromagnetic spins interaction in networked triarylamine polymers

Two hyperbranched polymers containing star-shaped conjugated triarylamine units altered with meta-phenylene units were synthesized. The polymers can be oxidized on chemically or electrochemically to radical cations which are the sources of electronic spins. The presence of meta-phenylenes in the polymers chemical structures allows for the ferromagnetic coupling of electronic spins which leads to the formation of high spin states. Quantitative magnetization measurements show that the doped polymers exhibit mainly S = 3/2 or S = 1 spin states, depending on the triarylamine couplers. The ferromagnetic exchange coupling constant J = +1 meV was estimated for the polymer 2, assuming a Heisenberg-type exchange.