Conducting polynaphthalenes from 1,1′-binaphthyl and 1,1′-bi-2-naphthol via electropolymerization

Polynaphthalene films with electrical conductivity of 10−3 S cm−1 were successfully electrosynthesized by direct anodic oxidation of 1,1′-binaphthyl (BN) and 1,1′-bi-2-naphthol (BNO) in CH2Cl2 containing additional boron trifluoride diethyl etherate (BFEE). The introduction of BFEE greatly lowered the onset oxidation potentials of the monomers compared with other supporting electrolytes. The resulting poly(1,1′-binaphthyl) (PBN) films exhibited good redox activity and stability in different monomer-free electrolytes. Moreover, FT-IR spectra and quantum chemistry calculation results proved that PBN and poly(1,1′-bi-2-naphthol) (PBNO) were both synthesized mainly through the coupling of the monomers at α-positions of the naphthalene ring. Fluorescence spectral determination showed that the polymers were typical blue light-emitters with solution quantum yields of 0.17 and 0.13, respectively. The substitution of hydroxyl and naphthyl groups did not change the emission wavelength of polynaphthalene (about 417 nm). Surface morphology determination revealed that regular particles with different sizes were orderly assembled on ITO electrode after electrochemical growth.