Synthesis, characterization, and ion responsive properties of hyperbranched oligofluorene using carbazole as a branching core

We report the synthesis of a triphenylamine-based hyperbranched oligofluorene (HPFT) containing a pendant terpyridine group by using Suzuki coupling polymerization. The effects of the hyperbranched structure on the photophysical, electrochemical, and chemosensory properties of HPFT are compared with those for linear oligofluorene (PFT). Both PFT and HPFT exhibit favorable thermal stabilities, with thermal decomposition temperatures greater than 406.7 °C. Increasing the polarity of organic solvents produces bathochromic shifts in the PL spectra of PFT and HPFT. Substitution with triphenylamine groups raised the ionization potentials of both PFT and HPFT, as confirmed by the highest occupied molecular orbital level (HOMO) of 5.10–5.22 eV below vacuum relative to PF without triphenylamine substitution (5.65 eV). PFT and HPFT containing pendant terpyridyl groups exhibit increased sensitivity to the Ni2+ ion, with Stern–Volmer constants (Ksv) of 1.86 × 104 M−1 and 5.01 × 104 M−1, respectively. Our results suggest that HPFT is a promising material for chemosensory applications.