Electron paramagnetic resonance studies of polymeric charge-transfer complexes

Electron paramagnetic resonance (EPR) spectroscopic studies are performed on a number of polymeric charge-transfer complexes with different polymer donors and low molecular weight acceptors. The g values, linewidths and spin concentrations at different temperatures have been determined. The results indicate that there is no change in the g values and linewidths with temperature. The signal intensity increases with temperature, which is typical of singlet-triplet systems separated by an activation energy. The spin concentration of the paramagnetic charge-transfer complexes generally increases with the strength of the donor-acceptor tendencies. The charge-transfer complexes transform finally to a diamagnetic product and this was confirmed by electronic absorption spectroscopy