CHIRALITY OF POLYVINYL COMPOUNDS .18. PREPARATION AND CHARACTERIZATION OF NEW OPTICALLY-ACTIVE COPOLYMERS WITH MAIN-CHAIN CHIRALITY CARRYING NAPHTHYL CHROMOPHORES
G. Wulff et al., CHIRALITY OF POLYVINYL COMPOUNDS .18. PREPARATION AND CHARACTERIZATION OF NEW OPTICALLY-ACTIVE COPOLYMERS WITH MAIN-CHAIN CHIRALITY CARRYING NAPHTHYL CHROMOPHORES, Macromolecules, 28(22), 1995, pp. 7434-7440
Optically active copolymers were obtained by radically initiated asymm
etric cyclocopolymerization of two new monomers, 3,4-O-cyclohexylidene
-D-mannitol 1,2;5,6-bis-O-[(4-vinylnaphthyl-1)]boronate] (2) and 3 4-O
-cyclohexylidene-D-mannitol 1,2;5,6-bis-O-[(2-vinylnaphthyl-1)boronate
] (3), with comonomers (e.g. methyl methacrylate) and subsequent split
ting off the chiral D-mannitol template. The copolymers are optically
active due to the chirality of the configuration of the main chain. Be
cause of the spatial proximity of the two naphthalene units in the sid
e chain of the copolymers circular dichroism (CD) spectra show strong
CD with exciton couplets. The configurations of the (4-vinylnaphthyl-1
)boronic acid and (2-vinylnaphthyl-1)boronic acid diad, respectively,
in the copolymer chains could be determined with the aid of the ''exci
ton chirality method''. In both cases the diads possess (S,S) configur
ation. The mechanisms of cyclopolymerization of the two monomers are d
iscussed on the basis of their conformations of lowest energy obtained
by calculations with semiempirical methods (AM1).