An AIE active BODIPY based fluorescent probe for selective sensing of Hg2+ via dual mechanism PET and CHEF

A pyrazole appended BODIPY ligand (L) is synthesized and thoroughly characterized by various spectroscopic studies ( 1 H, [Formula: see text]C, [Formula: see text]B, [Formula: see text]F, ESI–MS, UV-vis and fluorescence). The ligand (L) displays aggregation induced emission (AIE) in solution (a mixture of CH 3 OH and water) and solid state. The vital role of the restriction of intramolecular rotation (RIR) in AIE is supported by viscosity experiments and fluorescence lifetime studies. Photophysical behaviour and aggregate morphology is investigated by UV-vis, emission and scanning electron microscopy (SEM). Multiple strong intermolecular hydrogen bonds (C–H[Formula: see text]N and C–H[Formula: see text]F) play a significant role in the AIE response. In addition, L shows strong sensitivity toward Hg[Formula: see text]ion via chelation induced enhanced fluorescence (CHEF) mechanism. Job’s plot analysis suggested a 1:1 binding stoichiometry between L and Hg[Formula: see text], which has been further supported by electrospray ionization mass spectrometry and density functional theory.