Synthesis, characterization, electrochemistry and optical properties of a novel phenanthrenequinone- alt-dialkylfluorene conjugated copolymer

This paper describes the synthesis, characterization and electro-optical properties of a 9,10-phenanthrenequinone (PQ)-containing alternating conjugated copolymer: poly[(9, 10-phenanthrenequinone-2,7-diyl)-alt- (9,9-di-n-hexylfluorene-2,7-diyl)] (PPQF). The copolymer has good solubility in common organic solvents such as CH₂ Cl₂, CHCl₃ and tetrahydrofuran. The polymer structure was determined using ¹H NMR, Fourier transform infrared spectroscopy, gel permeation chromatography and elemental analysis. The polymer possesses a low-energy n ← π• electronic state caused by the C=O groups of the PQ repeating units, and exhibits interesting and improved electrochemical reduction activity as compared to poly(9,9-di-n-hexylfluorene-2,7-diyl) and molecular PQ. PPQF has no fluorescence in solution but shows interesting transitions from no fluorescence to strong fluorescence after it undergoes electrochemical reduction. The polymer PPQF may find use as a starting material for a range of applications and can also be used to prepare other polymers due to the presence of the PQ repeating units.