CHIRALITY OF POLYVINYL COMPOUNDS .10. ASYMMETRIC PERTURBATION OF SIDE-CHAIN CHROMOPHORES CAUSED BY THE MAIN-CHAIN CONFIGURATION OF OPTICALLY-ACTIVE VINYL-POLYMERS

After removal of the n-mannitol template, copolymers of 3,4-O-cyclohexylidene-D-mannitol l,2:5,6-bis-0-[(4-vinylphenyl)boronate] (1) with comonomers having aromatic chromophores obtained by free radical polymerization were investigated for their chiroptical properties. As comonomers, usually those containing aromatic systems of benzene, naphthalene, biphenyl, and stilbene with a varying distance of the chromophores from the polymerizable group were used. The copolymers are optically active due to the chirality of the configuration of the main chain. While the (S,S)-(4-vinylphenyl)boronic acid diads cause a strong negative Cotton effect at 233 nm, the aromatic comonomeric units generally bring about a positive Cotton effect at higher wavelength. Depending on the extent to which these two influences are operating, optical rotations varying from strongly negative to strongly positive were observed for the copolymers of different comonomers. The aromatic comonomeric unit shows the highest influence on the chiroptical properties if it is present as an isolated entity directly bound to the main chain. The asymmetry of the aromatic chromophore is caused by a conformational perturbation through the neighboring (S,S) diads. © 1990, American Chemical Society. All rights reserved.