Synthesis of polyfluorene and oligofluorene with N-1-hexylcytosine side chains and their sensing ability for nucleosides

摘要

Polyfluorene (PF) and oligofluorene (OF) with N-1-hexylcytosine side chains were synthesized by Pd-complex catalyzed condensation reactions starting from a newly synthesized monomer. The UV-vis spectra of the PF exhibit the absorption maximum at a longer wavelength than that of the OF, thus revealing that a pi-conjugation system extends along the polymer chain. The PF and OF are photoluminescent in solution, and their photoluminescence (PL) intensities are gradually decreased by the addition of nucleosides such as adenosine, cytidine, and guanosine to the solution. The decrease in PL intensity is likely caused by photoinduced charge transfer (PCT) from the PF's and OF's backbones to the nucleosides, within the complexes generated by hydrogen bonding between the PF and OF cytosine group at their side chains and the nucleosides. Among the nucleosides, guanosine acted as the most effective PL quenching agent. Cyclic voltammetry (CV) analysis of the OF showed that it is electrochemically active.