Indole-BODIPY: a “turn-on” chemosensor for Hg2+ with application in live cell imaging

Abstract

A new BODIPY, 2-(bis(1-methyl-1H-indol-3-yl)methyl)-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene bearing bis(1-methyl-1H-indol-3-yl)methyl unit at the β-pyrrolic position acting as a ‘turn-on’ chemosensor for Hg²⁺ in solution as well as in HeLa cells, is synthesized. The ‘off’ state of the probe is proposed to be a result of a photoinduced electron transfer (PET) process which gets inhibited in the presence of Hg²⁺ ions, leading to the ‘on’ state. We propose that the detection of Hg²⁺ ions proceeds via the interaction of the π-electron density of the electron rich indolic units of the BODIPY group with that of the acidic Hg²⁺ ions, restricting the PET. The sensing protocols are established by various spectroscopic/electrochemical/DFT studies.