Highly Fluorescent Cadmium Based Metal–Organic Frameworks for Rapid Detection of Antibiotic Residues, Fe³⁺ and Cr₂O₇^2– Ions

Abstract

Here, two novel 3D Cd(II)-MOFs, [Cd₃·<b>L</b>·(<b>BTB</b>)₂·2DMF] and [(Cd₃O₂)·<b>L</b>·<b>BTC</b>] (denoted as <b>CUST-532</b> and <b>CUST-533</b>, <b>L</b> = 9,10-bis(<i>N</i>-benzimidazolyl)-anthracene, <b>BTB</b> = 1,3,5-tris(4-carboxyphenyl) benzene, <b>BTC</b> = 1,3,5-benzenetricarboxylic acid, CUST = Changchun University of Science and Technology), were synthesized by solvothermal conditions. Both <b>CUST-532</b> and <b>CUST-533</b> are 3D (3,8)-c topological nets with the same point symbol of {4³}₂{4⁶·6¹⁸·8⁴}. PXRD and TGA analyses prove that <b>CUST-532</b> and <b>CUST-533</b> have good structural stability and thermal stability. On the basis of the high fluorescence characteristics, the results of fluorescence sensing experiments show that <b>CUST-532</b> and <b>CUST-533</b> can be used as multifunctional chemical sensors to achieve rapid fluorescence quenching response to antibiotic residues, Fe³⁺ and Cr₂O₇^2- ions at a much lower concentration. Furthermore, the possible mechanisms of fluorescence quenching in the sensing process were systematically studied by PXRD, UV-vis, fluorescence decay lifetime, and density functional theory.