Synthesis of optically active methacrylic oligomeric models and polymers bearing the side-chain azo-aromatic moiety and dependence of their chiroptical properties on the polymerization degree

Three oligomeric models (dimer, trimer and tetramer) of optically active methacrylic polymers containing in the side-chain the pyrrolidinyl group of one single configuration linked through the nitrogen atom to the azobenzene chromophore and the related homopolymers in a wide range of average polymerization degree (13 <Xn< 70) and different molecular weight distributions, were synthesized. Their characterization afforded the possibility to investigate the dependence of the properties on the average molecular weight of polymeric derivatives. In particular, the investigation of optical rotation and chiroptical properties by circular dichroism allowed to confirm the conformational origin of chirality in this class of materials as well as to correlate the optical activity to the molecular weight.