Facile synthesis of 5,8-linked quinoline-based copolymers

Coupling quinoline at its 5,8-positions provides a facile way to copolymerize quinoline with other conjugated moieties without breaking conjugation. Model compounds containing quinoline units, either at the periphery or in the core, were synthesized and one of them was characterized by X-ray diffraction. Copolymers of quinoline and 9,9-dialkylfluorene (R = n-octyl or 2-ethylhexyl) were synthesized in good yield by palladium-catalysed Suzuki cross-coupling. The copolymers are highly soluble in common organic solvents and gel permeation chromatography measurements against polystyrene standards showed the number-average molecular weight to be in the range (1.02-2.06) × 10 ⁴ g mol ^-1. Both copolymers emit in the blue region with an emission maximum centred at 435 nm.