Covalently Modified Graphene Oxide as Highly Fluorescent and Sustainable Carbonaceous Chemosensor for Selective Detection of Zirconium ion in Complete Aqueous Medium

Zirconium, a medically important transition metal, found extensive application and was found to be relatively safe, however, continuous exposure will lead to adverse effects. Though zirconium is considered as a safe metal in biomaterials, no reliable sensing methodologies have been developed. In the present report, for the detection of medically influential zirconium(IV) ions, a graphene-based carbonaceous material has been developed. Covalent modification of graphene oxide (GO) with 2-bis(pyridine-2-ylmethyl)amino)ethan-1-ol (PAE) provides a new material GOP which is characterized using various analytical techniques such as elemental analysis, energy dispersive spectroscopy (EDS), FTIR, PXRD, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and microscopic techniques SEM and HRTEM. All the analytical characterization techniques strongly supported the formation of covalently 2-bis(pyridine-2-ylmethyl)amino)ethan-1-ol tethered GO through an ester bond. Upon testing with a series of metal cations, intriguingly, an excellent photoluminescence response has been selectively originated from GOP with Zr(IV) in aqueous medium and it is utilized for the detection of Zr(IV). High selectivity toward Zr(IV) over the presence of other common coexisting metal ions was also demonstrated. Specific turn-on fluorescence response of GOP in the presence of Zr(IV) ion is rationalized via Fluorescence Resonance Energy Transfer (FRET) mechanism owing to the presence of ester bond as a spacer which brings PAE and GO closer. Further, the GOP is highly stable and sustainable, could recover and reuse for further sensor studies. The newly developed carbonaceous GOP material offers a new methodology for the detection of Zr(IV) in an aqueous medium with LOD of 27 ng/mL.