Metal‐organic Frameworks Containing Homophthalic Acid and Imidazole Ligands as Fluorescent Probes for the Detection of Fe ³⁺ , CrO ₄ ²⁻ , and Cr ₂ O ₇ ²⁻ Species in Aqueous Solutions

Abstract In this paper, a new metal‐organic framework, namely, [Zn(LBIX)(HPA) 2 ] n ( 1 ) (LBIX = 4,4′‐bis((1H‐imidazol‐1‐yl)methyl)‐1,1′‐biphenyl, H 2 HPA = Homophthalic acid) was synthesized and characterized, which can be used as a fluorescent probe for the detection of harmful heavy metals in water. The single‐crystal structure results indicated that complex 1 is composed of two‐dimensional planar structures, which are connected by intermolecular hydrogen bonding and stacked to form a 3D supramolecular structure. The fluorescence properties and potential for detecting heavy metal ions in water were also studied by anion and cationic sensing experiments. Complex 1 exhibited low detection limit (LOD) in Fe 3+ , CrO 4 2− , and Cr 2 O 7 2− fluorescence sensing experiments. Complex 1 also has good recyclability and stability in the detection of analytes. The possible mechanism of fluorescence burst was analyzed and the selectivity and sensitivity of complex 1 were further evaluated in competition experiments.