Synthesis and characterization of chiral main chain polyesters with polar segments tailored for second harmonic generation.

The synthesis, characterization and solvatochromic behavior of a new series of chiral polyesters are reported. These polymers with π-conjugated donor-acceptor segments were synthesized with a view to be suitable for second harmonic generation. The polyesters were prepared by the reaction of diacid chlorides with biphenolic azo chromophores with Λ-conformation and optically active dihydroxy compound (isosorbide). The polymers containing isosorbide units are optically active. They showed T_g between 100°C to 160°C and are stable up to 400°C. A red shift in the longer wavelength absorption band of these polymers in UV-Vis. absorption spectra (positive solvatochromism) shows that the dipole moment of excited state is higher than that of the ground state. Therefore these polyesters are expected to have good second harmonic generation capability. [ABSTRACT FROM AUTHOR]