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

Abstract

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 pK_a 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 K_SV 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.

Graphical Abstract

Keywords:

• Metal-organic framework
• luminescence sensing
• Fe³⁺ and Cr₂O₇²⁻ ions
• aqueous systems

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by NSFC (21671112 and 21905142), the Programme of Introducing Talents of Discipline to Universities (B18030), and China Postdoctoral Science Foundation (2019M651008).