One cadmium (II)-based metal-organic framework as high-efficiency multi-functional fluorescence chemosensor targeting for the determination of Fe3+, Cr2O72- and CrO42- in aqueous phase

Excessive discharge of metal ions, such as Fe3+ and Cr2O72-/CrO42- may bring about potential threats to human health and the ecological environment. Consequently, the assembly of function-oriented materials as effective chemosensors has the vital practical significance. In this article, four metal-organic frameworks (MOFs), namely, {[Co(bptb)(0.5)(bibp)(H2O)(2)]center dot H2O}(n)(I), [Mn-4(bptb)(2)(bibp)(3)(H2O)(4)](n)(II), [Ni-2(bptb)(bipy)(2)(H2O)(3)](n)(III) and [Cd-3(bptb)(2)(bipb)(3)(H2O)(4)](n) (IV) (H(4)bptb = 2,4,4',6-biphenyl tetracarboxylic acid, bibp = 4,4'-bis (imidazolyl) biphenyl, and bipy = 4,4'-bipyridine) have been hydrothermally synthesized, and their structures and physicochemical properties have been characterized and investigated. Single-crystal X-ray diffraction analysis reveals that they present fascinating three-dimensional configurations. Powder X-ray diffraction as well with ther-mogravimetric analysis demonstrates that Cd-MOF (IV) exhibits a high chemical and thermal stability. The studies of fluorescence properties show that IV may serve as a multi-responsive sensor for Fe3+ and Cr2O72-/ CrO42- ions with high sensitivity, selectivity and efficiency. Moreover, the fluorescence quenching mechanisms have been studied systematically depend on the inductively coupled plasma-atomic emission spectrometer (ICP-AES), X-ray photoelectron spectroscopy (XPS) analyses, PXRD analysis, FT-IR spectra, UV-vis spectra and SEM mapping (scanning electron microscope). In addition, magnetic and cyclic voltammetry (CV) properties of I-III have also been investigated. (C) 2021 Elsevier B.V. All rights reserved.