Highly stable Zn-MOF with Lewis basic nitrogen sites for selective sensing of Fe3+ and Cr2O72− ions in aqueous systems

A luminescent Zn(II)-based MOF, [Zn(dptz)(BDC)(H2O)]n [1, dptz = 3,6-di(1H-pyrazol-4-yl)-1,2,4,5-tetrazine, H2BDC = terephthalic acid], with Lewis basic nitrogen sites has been synthesized by a solvothermal method. Using ligands with higher pKa value, complex 1 exhibits excellent solvent and pH stabilities in the pH range 2–12. 1 can serve as a highly sensitive and efficient luminescent probe for detecting Fe3+ and Cr2O72− ions in aqueous systems. The values of KSV toward Fe3+ and Cr2O72− were estimated to be 1.61 × 103 M−1 and 1.26 × 104 M−1, respectively. The possible sensing mechanism has been discussed. All these results suggest 1 is a promising dual-functional luminescent sensor for the detection of Fe3+ and Cr2O72− ions in aqueous solution.