A Zn(II)-Organic Framework as a Fluorescent Probe for the Aqueous Phase Detection of Nitroaromatic Explosive and Cr(III) ion

Abstract

From the perspective of environment, civilian safety and human health it is utmost important to selectively and sensitively detect hazardous substances in the running water. In the last few decades, metal organic frameworks (MOFs) have been utilized for the detection of lethal substances in the aqueous phase using fluorescence method. Herein, a highly fluorescent MOF, Zn-MOF-1, namely, {[Zn2(pydc)2(DMF)]·2DMF}n, based on the ligand pyridine-2,5-dicarboxylic acid (H2pydc), was synthesized by employing solvothermal conditions. The Zn-MOF-1 was thoroughly characterized by crystallographic, PXRD, elemental, FTIR, and TG analysis. Single crystal data elucidated the exact structure of Zn-MOF-1. Due to its better emission spectra, the fluorescence sensing behavior of Zn-MOF-1 was checked in the aqueous medium. It was found that Zn-MOF-1 could detect Cr3+ with high sensitivity and selectivity and serve as an excellent fluorescent probe for TNP among other interfering nitroaromatic compounds in aqueous media. Furthermore, a plausible sensing mechanism has been demonstrated employing UV-Visible, fluorescence, and theoretical data. The observed Ksv values for TNP and Cr3+ are 2.1×108 M-1 and 1.46×107 M-1, respectively. Selective fluorescence quenching with high Ksv values and low detection limits validates the superior sensing performance shown by Zn-MOF-1 toward TNP and Cr3+. Thus, the fine-tuning of MOF for the detection of hazardous substances in wastewater is a challenging task and needs to address in future endeavors.