A new 3D four-fold interpenetrated dia-like luminescent Zn(ii)-based metal-organic framework: the sensitive detection of Fe3+, Cr2O72-, and CrO42- in water, and nitrobenzene in ethanol

A new three-dimensional zinc-based metal-organic framework, namely [Zn-2(4,4 '-nba)(2)(1,4-bib)(2)](n) (1), where 4,4 '-H(2)nba = 3-nitro-4,4 '-biphenyldicarboxylic acid and 1,4-bib = 1,4-bis(imidazole-1-ylmethyl)benzene, has been solvothermally synthesized and structurally characterized via single-crystal X-ray diffraction, IR spectroscopic, elemental, thermogravimetric, and Hirshfeld surface analyses. In the crystal structure of 1, the oxygen and nitrogen atoms of two 4,4 '-nba(2-) and two 1,4-bib ligands bind to the metal ion, creating irregular tetrahedral geometry. The 4,4 '-nba(2-) and 1,4-bib ligands serve as linear bidentate linkers to form a four-fold interpenetrated 3D framework with dia-like topology. Luminescence studies revealed that 1 can be used as a highly sensitive multi-responsive luminescent sensor for sensing Fe3+, Cr2O72-, and CrO42- in H2O, and nitrobenzene in C2H5OH. The detection limits of Fe3+, Cr2O72-, CrO42- and nitrobenzene can reach 1.76 mu M, 3.25 mu M, 3.8 mu M and 0.19 mu M, respectively. Moreover, 1 can be recycled at least five times for sensing Fe(iii) and Cr(vi). The sensitivity and stability of 1, 1@Fe3+, 1@Cr2O72, and 1@CrO42- were also investigated at different pH and temperature values. 1 exhibited satisfactory sensing abilities when the pH ranged from 3 to 10, and the temperature ranged from 5 degrees C to 75 degrees C, indicating that 1 could act as a fluorescent probe for Fe3+ under physiological pH conditions. These results support the idea that 1 has good anti-interference abilities and potential for sensing Fe(iii), Cr(vi) and nitrobenzene in real environments. In addition, the possible fluorescence quenching mechanism was explored in this paper.