New alternative copolymer constituted of fluorene and triphenylamine units with a tunable -CHO group in the side chain. Quantitative transformation of the -CHO group to -CH=CHAr groups and optical and electrochemical properties of the polymers

A new alternative functional copolymer, PFT, comprising of fluorene and triphenylamine units with a tunable -CHO group in the side chain was synthesized by the polycondensation of 4-[N,N-di(4-bromophenyl)amino]benzaldehyde with 9,9-dihexylfluorene-2,7-bis(trimethyleneborate) using Pd(PPh3)(4) as the catalyst. The polymer was soluble in organic solvents and gave a number-average molecular weight, M-n, of 10 000 and a weight-average molecular weight, M-w, of 17 700. PFT had an intrinsic viscosity [eta] of 0.24 dL g(-1) in toluene and exhibited the photoluminescence (PL) peak strongly influenced by the kind of the solvents, e.g., at 462 nm in toluene and at 528 nm in NMP. The quantum yield of the PL of PFT also varied from 12% in toluene to less than 1% in NMP. A cast film of PFT showed the emission peak at 497 nm. By using the Wittig reaction, the -CHO group of PFT was quantitatively transformed into trans -CH=CHAr groups. The modified products, MPa (Ar = -C6H6) and MPb (Ar = -C6H4OCH3-p), showed a UV-vis peak at 390 nm in solutions and in the solid. MPa and MPb showed PL peaks at 433 and 457 nm, respectively, in toluene. The quantum yields of MPa and MPb rose to 64% and 51%, respectively, from 12% of PFT. A cast film of MPa gave a quantum yield comparable to that of poly-(9,9-dioctylfluorene-2,7-diyl). PFT, MPa, and MPb were electrochemically active and received electrochemical oxidation, which was followed by cyclic voltammetry and UV-vis spectroscopy.