Photophysical behavior of sulfur-oxidized sulfone and trifluoromethyl-BODIPY: Insight into the relationship between...

Fluorine-substituted BODIPY probes have demonstrated outstanding performance in various biological imaging applications. In this study, a sulfone-mediated BODIPY fluorescent probe (BODIPY-CF₃/SO₂) for cell imaging was successfully synthesized. Single crystal diffraction experiments indicated that the probe molecule crystallized in the monoclinic P2₁/n space group, showing directional stacking and forming a rigid large conjugated system. Using the unmodified thioether probe (BODIPY-CF₃/S) as a control, the regulatory effect of the sulfone group on its photophysical properties and cell imaging performance was systematically investigated. The introduction of the sulfone group resulted in an alternating D-A-D-A conjugated structure overall, and also altered the electron cloud distribution and HOMO/LUMO orbital energy levels, thereby regulating the photoelectric properties of the probe and enhancing its stability. Spectroscopic experiments demonstrated that the sulfone probe possesses wide absorption and near-infrared emission capabilities, with a significantly larger Stokes shift than the thioether probe and is less affected by the microenvironment pH value. Cell imaging results proved that it can penetrate the HCT-116 cell membrane without a carrier and accumulate around the cell nucleus, exhibiting a more stable co-localization effect. Meanwhile, the cell activity test demonstrated that the probe had inhibitory effects on both HCT-116 cells and HeLa cells. Moreover, the molecular docking results indicated that the probe had a good interaction with the cell apoptosis regulatory factor Bcl-2, making it a potential target for tumor diagnosis and treatment.