Synthesis of nitropyridine-based π-conjugated polymers and their chemical properties

Abstract

π-Conjugated poly(3-nitropyridine-2,5-diyl) (PPy-3-NO2), poly(3,3′-dinitro-2,2′-bipyridine-5,5′-diyl) (PBpy-3,3′-diNO2), and a poly(arylene ethynylene) type polymer consisting of a 3,3′-dinitro-2,2′-bipyridine unit (PAE-1) were synthesized by Cu-promoted Ullmann coupling reaction and Pd-catalyzed coupling reaction. PPy-3-NO2 and PAE-1 were soluble in organic solvents such as DMSO, DMF, and chloroform, and gel permeation chromatography analysis showed a number average molecular weight (Mn) of 9,300 and 12,300, respectively. PPy-3-NO2 gave intrinsic viscosity, [η], of 0.53 dL g−1 in DMF. PBpy-3,3′-diNO2 had somewhat lower solubility. The polymers exhibited a UV–vis peak at about 430 nm. PPy-NO2 received electrochemical reduction at −1.5 V versus Ag+/Ag in acetonitrile, and gave an electrochemical redox cycle in a range from 0 to −1.1 V versus Ag+/Ag in an aqueous solution. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1763–1767, 2006