Sulfonic acid functionalized zirconium-based metal–organic framework for the selective detection of copper(ii) ions

Abstract

A zirconium-MOF with a sulphonic acid functionalized biphenyldicarboxylic acid linker was synthesized by a solvothermal process. The material was characterized by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) analysis, infrared (IR) spectroscopy, energy-dispersive X-ray spectroscopy (EDX), and FESEM analysis. The fluorescence sensing experiment towards the detection of Cu²⁺ was carried out. The detection time for Cu²⁺ was only 15 s with a very low limit of detection, which is 0.22 μM. The Stern–Volmer constant was found to be 5.5 × 10⁵ M⁻¹. For easy handling and real field application purposes, we developed a paper-strip based sensing device. The systematic study of the mechanism by EDX, PXRD, TRPL, and UV-Vis spectroscopy revealed that the quenching of fluorescence intensity by copper(II) was due to the fluorescence resonance energy transfer.