Preparation and Properties of 4-Dialkylamino-phenyl N-Functionalized 2,7-Linked Carbazole Polymers

Abstract

The preparation of 2,7-linked carbazole polymers with 4-dialkylamino-phenyl substituents is presented. Poly(9-(4-dioctylamino-phenyl)-9H-carbazole-2,7-diyl) P1 and poly(3,6-dimethyl-9-(4-dioctylamino-phenyl)-9H-carbazole-alt-9-(4-dioctylamino-phenyl)-9H-carbazole-2,7-diyl) P2 were prepared through a Suzuki coupling polymerization route. The polymers were characterized by NMR spectroscopy, UV−vis absorption spectroscopy, and fluorescence spectroscopy and their molecular weights were estimated using gel permeation chromatography. Polymer P1 had one of the highest average molecular weights reported for 2,7-linked carbazole main chain conjugated polymers. Both polymers showed unusual photophysical properties with solvent-dependent emission spectra. The fluorescence quantum yields of the polymers were also determined both in solution as well as in the solid state. Cyclic voltammetric studies on these polymers reveal reversible oxidation waves up to 0.7 V (vs Ag/Ag+) for polymer P1 and up to 1.0 V for polymer P2. The polymers also displayed low ionization potentials as a result of their N-substitution with the 4-dialkylamino-phenyl substituents.