A Water-Stable Metal–Organic Framework for Highly Sensitive and Selective Sensing of Fe3+ Ion

A new metal-organic framework [Zn₅(hfipbb)₄(trz)₂(H₂O)₂] (NNU-1) [H₂hfipbb = 4,4'-(hexafluoroisopropylidene)bis(benzoic acid), Htrz = 1H-1,2,3-triazole] was assembled by hydrothermal synthesis. Single-crystal X-ray diffraction analysis reveals that NNU-1 displays a twofold interpenetrating three-dimensional (3D) framework with a {4²⁴·6⁴}-bcu topology. Interestingly, the 3D framework contains a two-dimensional (2D) layered structure that consists of alternating left- and right-handed double helical chains. On the basis of the hydrophobic -CF₃ groups from H₂hfipbb ligand, NNU-1 possesses excellent stability in water. It is worth noting that NNU-1 not only shows a highly selective fluorescence quenching effect to Fe³⁺ ion in aqueous solution but also resists the interference of other metals including Fe²⁺ ion. Accordingly, NNU-1 probably functions as a potential promising fluorescence sensor for detecting Fe³⁺ ion with high sensitivity and selectivity.