Novel Electroactive Proton-Doped Conducting Poly(aromatic ethers) with Good Fluorescence Properties via Electropolymerization

Low-potential electrochemical polymerization of a series of aromatic ethers in boron trifluoride diethyl etherate (BFEE), such as diphenyl ether (DPE), 1,4-diphenoxybenzene (DPOB), and 2,2′-dinaphthyl ether (DNE), led to successful deposition of a new class of electrically conducting proton-doped poly(aromatic ethers) thin films exhibiting good electroactivity and high thermal stability, whereas their sulfur analogues, diphenyl sulfide (DPS) and diphenyl sulfone (DPSO), were not eletropolymerizable. FT-IR, ¹H NMR spectra, and computational results demonstrated that poly(1,4-diphenoxybenzene) (PDPOB) were synthesized mainly through the coupling of DPOB at para-positions, while the polymerization of DNE occurred probably at α- and C₆-positions of the naphthyl rings to form poly(2,2′-dinaphthyl ether) (PDNE) with complex structure. It was found that the electrodeposited poly(aromatic ethers) probably showed proton-doping nature similar to polyaniline based on FT-IR spectral results and conductivity investigation. As-formed PDPOB and PDNE were typical blue light emitters and highly fluorescent, with solution quantum yields of as high as 0.40 and 0.18, respectively. Surface morphology determination revealed that regular and homogeneous microspheres with diameters in the range from 200 nm to 1 μm were assembled on ITO electrode after electrochemical growth. Electro-oxidation of aromatic ethers therefore offers a ready route to novel conducting, redox-active, luminescent conjugated polymers. These materials open up a new, unexplored, and potentially vast area of research on poly(aromatic ethers) and hold promise for the design of a new generation of optoelectronic materials.