On chirality induction in poly(phenylenedisilanylene)s

Abstract

A series of poly(m- and p-phenylenedisilanylene)s with a chiral oligo(ethylene glycol) side chain were synthesized and their chiroptical properties as a function of the position of the chiral substituent in the side chain and the position of the phenylene link in the main chain were studied. Poly(m-phenylenedisilanylene)s with a chiral tri(ethylene glycol) side chain m-1 displayed optical activity arising from solvophobic and metal-coordination interactions. However, the induced optical activity showed a dependence on the position of the chiral center in the side chain. As the position of the chiral center of the side chain was moved away from the main chain, the induced Cotton effect was only observed at low temperature, in a polar solvent, indicating that the optically active side group with a different position of the chiral center showed some ability, albeit small, to induce optical activity in the polymer. The sign of the observed Cotton effect also alternated with the position of the chiral center of the side chain on the solvation- and metal-coordination-driven chirality induction in the polymers. In addition, poly(p-phenylenedisilanylene) with chiral ethylene glycol side chains p-1 displayed the Cotton effect in polar and nonpolar solvents.