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

• Four MOFs were prepared and characterized. • Cd-MOF behaves a multi-functional chemosensor toward Fe 3+ , Cr 2 O 7 2− and CrO 4 2– . • Sensing mechanisms of Cd-MOF are supported by PXRD, ICP-AES, FT-IR spectra, UV−vis or XPS and SEM mapping. • Magnetic and cyclic voltammetry properties of Ι−Ⅲ have been investigated. Four MOFs have been synthesized and characterized. Cd-MOF (Ⅳ) behaves as a multi-responsive fluorescence chemosensor targeting for the determination of Fe 3+ , Cr 2 O 7 2– and CrO 4 2– in aqueous with high sensitivity, selectivity and anti-interference ability. Sensing mechanisms have been discussed in detail. Excessive discharge of metal ions, such as Fe 3+ and Cr 2 O 7 2– /CrO 4 2– 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)(H 2 O) 2 ]·H 2 O} n ( Ι ), [Mn 4 (bptb) 2 (bibp) 3 (H 2 O) 4 ] n ( Ⅱ ), [Ni 2 (bptb)(bipy) 2 (H 2 O) 3 ] n ( Ⅲ ) and [Cd 3 (bptb) 2 (bipb) 3 (H 2 O) 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 thermogravimetric 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 Fe 3+ and Cr 2 O 7 2– /CrO 4 2– 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 Ι − Ⅲ have also been investigated.