A white light emitting single halochromic hydrazine bridged bis(3-pyrrolyl BODIPY) fluorophore

In search of white light emitting fluorophores, a hydrazine bridged Schiff base compound, bis(3-pyrrolyl BODIPY), was synthesized by condensing readily available alpha-formyl 3-pyrrolyl BODIPY with hydrazine hydrate in CH3OH under reflux for 5 h followed by recrystallization. Bis(3-pyrrolyl BODIPY) was thoroughly characterized by HR-MS, 1D and 2D NMR, and X-ray crystallography. The X-ray structure revealed that the 3-pyrrolyl BODIPY units in the dyad were arranged trans to each other with respect to the hydrazine moiety. Bis(3-pyrrolyl BODIPY) showed absorption bands in the region of 390-705 nm and exhibited multiple fluorescence bands in the region of 395-720 nm at different excitation wavelengths. The protonated derivative of bis(3-pyrrolyl BODIPY) generated by the addition of TFA to its CH2Cl2 solution showed significant changes in the optical properties and generated white fluorescence under UV light with specific emission bands observed in blue, green, and red regions, indicating that bis(3-pyrrolyl)BODIPY is a single white light emitting halochromic fluorophore under acidic conditions. DFT and TD-DFT studies justify the structural and electronic properties of the protonated derivative of bis(3-pyrrolyl BODIPY) exhibiting white light emission. A single halochromic hydrazine bridged bis(3-pyrrolyl BODIPY) fluorophore was synthesized and the white light emission of the fluorophore in its protonated form was demonstrated.

Automated summary

A new compound, bis(3-pyrrolyl BODIPY), was synthesized and its catalytic potential was studied by adjusting the optical properties. The compound exhibited white light emission under acidic conditions.