Modulating the Optoelectronic Properties of Tripodal Fluorophores Through Fluorine-Substituted Peripheral Phenyls

Fourteen novel tripodal fluorophores based on a central triphenylamine donor, electron-rich, and polarizable divinylthiophene linker, and eight different fluorine-based substituents have been designed and prepared via a straightforward four-step sequence. Altering the peripheral F-substitution has been demonstrated to largely affect their fundamental properties such as thermal robustness (210-420 °C), the LUMO energies (E_LUMO = -2.35 to -3.11 eV), the HOMO-LUMO gap (ΔE = 2.07-2.66 eV), and the absorption/emission maxima (λ_max ^A/E = 442-478/521-678 nm). The experimental data, corroborated by DFT calculations, further revealed twofold and tunable ICT employing both central triphenylamine and auxiliary thiophene donors, and the peripheral F-substitution either boosting or switching-off two-photon absorption activity. Whereas the ─SF₅ groups impart an exceptional cross-section of 1930 GM, the ─COCF₃ group may completely suppress the nonlinear optical response.