Conformational Steering in Substituted Poly(3,6-phenanthrene)s: A Linear and Nonlinear Optical Study

The synthesis of a chiral, 9, 10-dialkoxy-functionalized poly(3,6-phenanthrene) and the study of its chiroptical properties in different solvents is reported. The polymer was prepared by a Suzuki cross-coupling reaction. UV-vis, circular dichroism, and fluorescence spectroscopy and hyper-Rayleigh scattering were used to demonstrate that this polymer adopts a random coil conformation in a good solvent and folds into a one-handed helical conformation in poor solvents rather than stacking in a chiral way. Hyper-Rayleigh scattering proved to be a powerful tool for the investigation of the conformation of conjugated polymers because its response strongly depends on the conformation of the polymer.