Regioselective synthesis of α-nitro BODIPYs <i>via</i> Cu(NO₃)₂ ⋅3H₂ O or NO₂BF₄-promoted direct nitration

A series of [Formula: see text]-nitro BODIPY dyes were obtained in moderate to high yields using cupric nitrate or nitronium tetrafluoroborate. Both methods allow for the regioselective electrophilic aromatic nitration of the pyrrolic positions under mild conditions, providing a series of [Formula: see text]-nitro BODIPYs in 30–85% yields. These novel dyes were fully characterized by NMR spectroscopy and HRMS. The photophysical properties of these BODIPYs were analyzed using UV-Vis, fluorescence spectroscopy and DFT calculations. The introduction of the nitro group led to notable redshifts in the absorption and emission bands, decreasing in molar absorptivity, and a reduction in fluorescence quantum yields of these BODIPYs. Furthermore, the electron-withdrawing character of the nitro substituent induces reduced HOMO and LUMO energy levels. In addition, representative transformation experiments, such as conversion to amines, were performed to investigate potential applications of these novel [Formula: see text]-nitro BODIPY dyes.