Donor–Acceptor Conjugated Copolymers Containing Transition-Metal Complex: Intrachain Magnetic Exchange Interactions and Magneto-Optical Activity

A donor–acceptor conjugated copolymer containing thienothiophene (donor) units and Co(II) complexes (acceptor) has been synthesized and characterized. The studies of magnetic properties of the polymers by SQUID and EPR measurements showed antiferromagnetic exchange interaction between neighboring spin centers along with the polymer backbone through intrachain interactions. It is the first time that the D–A conjugated polymer backbone serves as bridging ligands for magnetic couplings, making these type of polymers promising as magnetic materials. Moreover, the magneto-optical activity of polymer LCP1 was characterized using magnetic circular dichroism spectroscopy. It was found that the material exhibits a large magneto-optic rotation with a peak Verdet constant of 2980 deg·T–1·m–1 at 590 nm.