A Boron Dipyrromethene‐Based Fluorescence ‘OFF‐ON’ Probe for Sensitive and Selective Detection of Palladium(II) Ions and Its Application in Live Cell Imaging

Abstract

A novel boron dipyrromethene (BODIPY)-based fluorescent probe BDPÀ Pd was designed and synthesized. Upon coordination with Pd 2 + , the emission of the probe at 508 nm significantly increased, showing an 'OFF-ON' fluorescence response. The complexation of BDPÀ Pd with Pd 2 + in both acetonitrile and aqueous solution were then studied by absorption and fluorescence spectra. The binding stoichiometry between the probe and Pd 2 + was found to be 1 : 2, and the binding constant was determined to be 8.5 × 10 10 M À 2 and 8.2 × 10 10 M À 2 in acetonitrile and aqueous solution, respectively. The probe exhibited a detection limit as low as 0.72 ppb toward Pd 2 + with no obvious interference from up to 21 species of common metal ions, suggesting BDPÀ Pd as a sensitive and selective fluorescent probe for Pd 2 + detection. The fast fluorescence 'OFF-ON' phenomenon of the probe upon coordination with Pd 2 + ions could be easily observed by a hand-hold UV lamp under naked eye in solution as well as on homemade test trips. Density functional theory (DFT) calculations were carried out to give the optimized structure of complex BDPÀ Pd : 2Pd 2 + and rationalize the detection mechanism through a prohibited intramolecular photoinduced electron transfer (PET) process. The bio-imaging application of the probe was investigated and it showed excellent cell permeability for fluorescent imaging of Pd 2 + ions in A549 human non-small cell lung cancer cells.

BODIPY Immobilized MCM‐41 Based Multianalyte Sensor: Application in Detection and Removal of Trivalent (Al3+, Cr3+) and Divalent (Cu2+, Hg2+) Metal Ions in Aqueous Media

“…The MS4 shows weak emission properties originally due to the movement of lone pair of electrons present on the −NH group of the 4‐aminobenzoic acid unit towards the BODIPY core (PET “ON” state); Figure S40a. When MS4 interacts with Al 3+ and Cr 3+ metal ions, it causes the involvement of electron density at −NH with the metal ions resulting in PET “OFF”; which enhances the fluorescence of the fluorophore unit [93,94] . In contrast, MS4 forms a complex with Cu 2+ and Hg 2+ ions by the deprotonation of the −COOH group resulting in fluorescence quenching.…”

“…When MS4 interacts with Al 3 + and Cr 3 + metal ions, it causes the involvement of electron density at À NH with the metal ions resulting in PET "OFF"; which enhances the fluorescence of the fluorophore unit. [93,94] In contrast, MS4 forms a complex with Cu 2 + and Hg 2 + ions by the deprotonation of the À COOH group resulting in fluorescence quenching. This could be because the reduced electron density on the BODIPY core triggers an oxidative photoinduced electron transfer mechanism.…”

Fluorescent and chromogenic organic probes to detect group 10 metal ions: design strategies and sensing applications

“…In an elegant study, Chen et al 156 (in 2020) developed naphthylamine-based BODIPY probe 35 for the detection of Pd( ii ) using the PET mechanism (Fig. 27).…”

Triphenylamine-equipped 1,8-naphthaolactam: a versatile scaffold for the custom design of efficient subcellular imaging agents

“…The former two primarily allow for high signal-to-noise ratios, while the latter two allow for dynamic and targeted examinations. Most commercial and published fluorescence bioprobes, such as anthocyanins, 25 fluoresceins, 26 rhodamines, 27 and boron dipyrromethenes, 28 belong to the aggregation-caused quenching (ACQ) type fluorophore, and the aggregation-induced emission (AIE) ones are flourishing as the next-generation fluorophore. [29][30][31][32][33][34][35] However, it is worth noting that both ACQ-and AIE-active fluorescence bioprobes still suffer from concentration-dependent erroneous signal reading in practical bioimaging, even leaving aside the above four requirements.…”