New optically active methacrylic polymers bearing side-chain bisazoaromatic moieties

The synthesis of three novel optically active monomers containing a side-chain chiral moiety linked to a photochromic bisazoaromatic chromophore, such as (S)-3-methacryloyloxy- 1-[4'-phenylazo-(4-azobenzene)]-pyrrolidine [(S)-MPAAP], (S)-3-methacryloyloxy-1-[4'-cyanophenylazo(4-azobenzene)]-pyrrolidine [(S) -MPAAP-C] and (S)-3-methacryloyloxy-l-[4'-nitrophenylazo-(4-azobenzene)]-pyrrolidine [(S)-MPAAP-N], is described. Each monomer has been radically homopolymerized to afford the corresponding optically active polymeric derivative, which have been characterized, in solution and in the solid state, and their properties compared to those of the monomers and of analogous homopolymers bearing only one azoaromatic chromophore in the side chain. The optical activity displayed by the polymers is discussed in terms of extent of chiral conformation assumed by the macromolecules as a consequence of their stiffness and the dipole-dipole interactions between the bisazoaromatic chromophores.