New highly luminescent cationic polyelectrolytes based on poly(phenylenevinylene-alt-fluorenevinylene) or poly(fluorenevinylene) derivatives and their neutral precursors

Poly(phenylenevinylene-alt-fluorenevinylene) (PF) or poly(fluorenevinylene) (F) derivatives that carried alkyl chains with terminal tertiary amino groups were successfully synthesized via Heck coupling. They were postquaternized by reacting with bromoethane to the corresponding cationic polyelectrolytes PFQ and FQ. The neutral polymers PF and F as well as the quaternized polymer FQ were soluble in common organic solvents such as THF, chloroform, dichloromethane, and toluene. In contrast, the quaternized polymer PFQ did not dissolve in these solvents but was soluble in environmentally friendlier solvents like water and alcohols. The neutral precursors exhibited higher thermal stability and glass-transition temperatures than the corresponding quaternized counterparts. All polymers emitted intense blue-greenish light in solution (462-489 nm) with relatively high photoluminescence (PL) quantum yields 0.32-0.57, and as thin films (475-557 nm) with optical band gaps of 2.482.57 eV The water soluble PFQ could find potential applications as chemo or biosensor. (c) 2006 Wiley Periodicals, Inc.