Synthesis, photophysical, and electrochromic characterization of wholly aromatic polyamide blue-light-emitting materials

[[abstract]]A new carbazole-derived triphenylamine-containing aromatic dicarboxylic acid monomer, 4,4'-dicarboxy- 4"-N-carbazolyltriphenylamine, with blue light ( 460 nm) fluorescence quantum yield of 40% was successfully synthesized by the cesium-fluoride-mediated condensation of N-(4-aminophenyl) carbazole with 4-fluorobenzonitrile, followed by alkaline hydrolysis of the dinitrile intermediate. A series of novel poly(amineamide)s with pendent N- phenylcarbazole units having inherent viscosities of 0.36-0.61 dL/g were prepared from the newly synthesized dicarboxylic acid monomer and various aromatic diamines by direct phosphorylation polycondensation. The obtained polymers were amorphous and could afford flexible, transparent, and tough films with good mechanical properties. They had useful levels of thermal stability associated with relatively high glasstransition temperatures (269-322 degrees C). These polymers exhibited strong UV-vis absorption maxima at 340361 nm, and their photoluminescence showed emission peaks around 449-465 nm with quantum yields up to 46% in NMP solution. The hole-transporting and electrochromic properties were examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the poly(amine-amide) films prepared by casting polymer solution onto an indium-tin oxide (ITO)-coated glass substrate exhibited one reversible oxidative redox couples at potentials of 1.11-1.18 V vs Ag/AgCl in acetonitrile solution due to oxidation of main-chain triphenylamine unit. The polymer films revealed excellent stability of electrochromic characteristics for the radical cations generated, changing color from original yellowish to deep blue.[[note]]SC