A ratiometric fluorescence probe for selective visual sensing of Zn2+.
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.
Ajayaghosh
Ayyappanpillai
A
Photosciences and Photonics Group, Chemical Sciences Division, Regional Research Laboratory, CSIR, Trivandrum, India. aajayaghosh@rediffmail.com
Carol
Priya
P
Sreejith
Sivaramapanicker
S
D015374:Biosensing Techniques / Q000379:methods*; D002413:Cations, Divalent; D031541:Fluorescence Resonance Energy Transfer; D005456:Fluorescent Dyes / Q000737:chemistry*; D008670:Metals / Q000032:analysis / Q000737:chemistry; D011874:Radiometry / Q000379:methods*; D013050:Spectrometry, Fluorescence; D015032:Zinc / Q000032:analysis* / Q000737:chemistry
D002413:Cations, Divalent; D005456:Fluorescent Dyes; D008670:Metals; D015032:Zinc