Influence of monomer optical purity on the conformation and properties of chiral, donor-embedded polybinaphthalenes for nonlinear optical purposes

A series of chiral, chromophore-functionalized donor-embedded polybinaphthalenes were prepared by a Stille coupling reaction between a diiodo-functionalized chromophore and a bis(trimethyltin)binaphthalene derivative. The optical purity of the chiral binaphthalene monomer was varied, and its influence on the conformation of the polymers was investigated. Differential scanning calorimetry and second-harmonic generation experiments revealed that the mobility of the chromophore in the polymers, prepared from optically impure monomers, is much higher than that in polymers obtained by polymerization of optically pure monomers. Hyper-Rayleigh scattering measurements demonstrated that this difference in mobility is due to a different macromolecular structure.