A New Synthetic Route to Soluble Polyquinolines with Tunable Photophysical, Redox, and Electroluminescent Properties

A new monomer bearing dialkyl groups, 3,3‘-dinonanoylbenzidine, when copolymerized with diacetyl monomers gave six new alternating conjugated copolymers, poly(2,2‘-arylene-4,4‘-bis(4-alkylquinolines))s, which are soluble in organic solvents. The thermal, electrochemical, photophysical, and electroluminescent properties of the new polyquinolines varied with the arylene linkage, including p-phenylene, 4,4‘-biphenylene, stilbene, 5,5‘-bithienylene, bis(thienyl)vinylene, and 3,7-phenothiazinylene. The new conjugated polymers combined high glass transition temperature (110−254 °C) with quasi-reversible electrochemical reduction from which 2.72−3.00 eV electron affinities were estimated. The optical band gap varied from 2.19 to 2.86 eV whereas the photoluminescence emission maximum varied from blue-green (477 nm) to deep red (646 nm). Some of the new polymers with alternating donor−acceptor architecture showed strong intramolecular charge transfer. Electroluminescence of moderate brightness (up to 209 cd/m2) wa...