CHIRALITY OF POLYVINYL COMPOUNDS .6. UNUSUAL INFLUENCES OF THE COMONOMER STRUCTURES ON THE CHIROPTICAL PROPERTIES OF OPTICALLY-ACTIVE VINYL COPOLYMERS WITH CHIRALITY ARISING FROM CONFIGURATIONAL RELATIONSHIPS IN THE MAIN CHAIN

In contrast to appreciable negative optical rotations shown by most of the vinyl copolymers of 3,4-O-cyclohexylidene-D-mannitol 1,2:5,6-bis-O- left bracket (4-vinylphenyl)boronate right bracket after removal of the D-mannitol template, copolymerizations of this monomer with styrene derivatives bearing functional groups in conjugation with the phenyl ring yielded copolymers which, after removal of the D-mannitol template, showed positive optical rotations. Copolymers obtained by using comonomers bearing the modified versions of these functional groups exhibited negative optical rotations. Interestingly, upon transforming the cyano, formyl, and methoxycarbonyl groups of the copolymers to the corresponding aminomethyl and hydroxymethyl groups by polymer analogue reactions, the formerly positively rotating polymers showed negative optical rotations. With the help of chiroptical techniques, particularly circular dichroism (CD), the unique role of the comonomer structures in this unusual behavior of the copolymers is elucidated. While the absolute configuration of the distyryl diads generated from the monomer remains the same with all comonomers, in the case of the comonomers with conjugated chromophoric systems strong Cotton effects are induced, thus generating positively rotating polymers.