A Ratiometric Fluorescence Probe for Selective Visual Sensing of Zn²⁺

Abstract

A simple ratiometric fluorescence probe based on vinylpyrrole end-capped bipyridine for the visual sensing of Zn2+ under aqueous physiological pH (6.8-7.4) is described. The fluorophores 3a-c showed strong emission around 537 nm in acetonitrile with a quantum yield of 0.4. In buffered (HEPES, pH 7.2) acetonitrile-water mixture (9:1 v/v), titration of transition metal salts to 3c showed strong quenching of the emission at 547 nm except in the case of Zn2+, which resulted in a red-shifted emission at 637 nm. Alkali and alkaline earth metal salts could not induce any considerable changes to the emission behavior of 3a-c. The binding of Zn2+ was highly selective in the presence of a variety of other metal ions. Though Cu2+ quenches the emission of 3c, in the presence of Zn2+, a red emission prevails, indicating the preference of 3c toward Zn2+. Job plot and Benesi-Hildebrand analysis revealed a 1:1 complexation between the probe and the metal ion. The selective visual sensing of Zn2+ with a red emission is ideally suited for the imaging of biological specimens.

Zn2+‐Triggered Drug Release from Biocompatible Zirconium MOFs Equipped with Supramolecular Gates

“…[ 1 ] The brain has the highest zinc content with respect to other organs: in brain extracellular fl uids, free zinc is approximately 500 n m in concentration; however, in the synaptic vesicles of corner tetrahedral cages (free diameter: ≈8 Å) by means of trigonal windows (≈6 Å). [ 21 ] Zr, a silvery, lustrous, and strong transition metal, is widely distributed in nature and found in all biological systems and unique presence in the human brain, often in appreciable amounts.…”

Probing Receptor–Anion Interactions by Ratiometric Chemosensors Containing Pyrrolecarboxamide Interacting Sites

“…[1c,3e,4b,4e,7b-7d,7f,9] Among the various signal-reporting techniques for analyte-receptor interactions, colorimetric and ratiometric fluorescence sensing offer several advantages, including visual monitoring, precise detection without interference due to medium effects, and an enhanced dynamic range, over simple detection based on fluorescence quenching or enhancement. [10] The ratio of the emission intensities at two different wavelengths is sufficient to determine the analyte concentration independent of probe concentration or any instrument-related parameters. The design of colorimetric and ratiometric fluorescence chemosensors also provides the basis for the manipulation and engineering of various photophysical processes with the ultimate goal being the selective and sensitive signaling of targeted species.…”

A novel small molecule fluorescent sensor for Zn2+ based on pyridine–pyridone scaffold

“…However at this point we are not able to conclude, which tautomer pyridine or pyridone of 3 is responsible for the chelation and CHEF effects with Zn 2+ . Ajayaghosh et al developed pyrrole end-capped 5,5'-divinyl-2,2'-bipyridyl derivative, a ratiometric fluorescence probe for Zn 2+ which was designed to use the bipyridyl moiety as a metal chelator [33]. The pyridine-pyridone part of our newly developed 3 needs NH or OH proton for CHEF effects with Zn 2+ .…”