Enhanced removal of organic dyes from aqueous solutions by new magnetic HKUST-1: facile strategy for synthesis.

A novel, magnetic HKUST-1 MOF based on MgFe2O4-NH2 was designed and synthesized in two steps and applied effective removal of malachite green (MG), crystal violet (CV), and methylene blue (MB) from water samples. Characterization of the newly synthesized MgFe2O4-NH2-HKUST-1 was performed by various techniques such as Fourier transform infrared spectroscopy, X-ray diffraction, Field emission scanning electron microscopy, Brunauer-Emmett-Teller, Thermal gravimetric analysis, and Vibration sampling magnetometry. Malachite green, crystal violet and methylene blue are toxic and mutagenic dyes that can be released into the water in different ways and cause many problems for human health and the environment. The removal of malachite green, crystal violet, and methylene blue from aqueous solutions was investigated using the magnetic HKUST-1 in this research. The effect of various parameters such as pH, amount of sorbent, dye concentration, temperature, and contact time on dye removal has been studied. The results showed that more than 75% of dyes were removed within 5 min. Adsorption isotherms, Kinetic, and thermodynamic studies were investigated. The results of this study show that adsorption capacity of the magnetic adsorbent is equal to 108.69 mg g-1 for MG, 70.42 mg g-1 for CV, and 156.25 mg g-1 for MB. This study shows the good strategy for the synthesis of the functionalized magnetic form of HKUST-1 and its capability for increasing the efficiency of the removal process of malachite green, crystal violet, and methylene blue from an aqueous solution.

Ln Based Metal-organic Framework for Fluorescence "Turn Off-On" Sensing of Hg2.

A highly luminescent Ln-MOF [La3(NDC)4(DMF)3(H2O)4]n, (NDC = 2, 6 naphthalen dicarboxylic acid) was designed and synthesized. The structure was characterized by x-ray single structure determination, TGA, IR spectra and PXRD and fluorescence spectroscopy. The structure shows high fluorescence intensity based on the presence of lanthanide metal and ligand. In the presence of I-, the emission can be effectively quenched introducing turn off system. Furthermore, the synthesized Ln-MOF can recognize Hg (II) by showing fluorescence turn-on signal because of the high affinity between Hg (II) and I-. Moreover, the high selectivity and sensitivity of the synthesized Ln-MOF makes it quit qualified for determination of the low concentration of mercury (2.00 nM).

HKUST-1 metal-organic framework for dispersive solid phase extraction of 2-methyl-4-chlorophenoxyacetic acid (MCPA) prior to its determination by ion mobility spectrometry.

The authors describe a method for the extraction of the herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA) from agricultural products. The metal organic framework (MOF) HKUST-1 (a copper(II) benzene-1,3,5-tricarboxylate) was used as a sorbent for efficient clean-up and preconcentration of MCPA. The effects of pH value, stirring time, amount of sorbent on extraction were optimized by central composite design. Ultrasonic waves were used for desorption procedure and its advantage was demonstrated for an increase in extraction recovery. Corona discharge ion mobility spectrometry (IMS) was then applied for fast and sensitive determination of MCPA. The method was validated in terms of sensitivity, recovery and reproducibility. Under the optimum conditions the calibration plot is linear between 0.035-0.200 µg. L-1. The detection limit is 10 ng L-1, with relative standard deviations of <5%. Real samples (water, soil and agricultural product) were spiked and then analyzed by this method, and the results revealed efficient solid phase extraction and recovery. Graphical abstract Schematic presentation of a procedure for extraction of an organochlorine pesticide (2-methyl-4-chlorophenoxyacetic acid) from agriculture products using the HKUST-1 metal-organic framework prior to determination by ion mobility spectrometry based on its ionization in drift cell.

Sonochemical synthesis and characterization of a new nano Ce(III) coordination supramolecular compound; highly sensitive direct fluorescent sensor for Cu2.

Micro and nano-structures of a new Ce(III) Coordination supramolecular compound, [Ce (1,5-NDS)1.5(H2O)5]n,1, (1,5-Naphthalenedisulfonic acid), were prepared using hydrothermal and sonochemical approaches, respectively. These new micro and nano structures were characterized by elemental analysis, IR spectra, thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), and powder X-ray diffraction. The X-ray single crystal structure determination of 1 shows that it features a neutral 2D framework based on the [Ce2H20O16S2] clusters as a secondary building unit (SBU) which shows a sql/Shubnikov tetragonal plane net. Moreover by considering the H-bonds, the final structure can be considered as 3D supramolecular network. The influence of ultrasound irradiation time on the morphology and size of the nanostructure 1 was investigated. The results indicated that by increasing the time of ultrasonic radiation, smaller nanostructures form and morphological changes occur. Fluorescent properties of the nanoparticles of 1 were also investigated. Coordination polymer 1 shows high fluorescence intensity and good tendency to copper ion that can be used as an optical sensor for selective and sensitive determination of Cu2+ in aqueous media with detection limit of 3.0µM.

Potassium ion-mediated non-covalent bonded coordination polymers.

Crystal structures and vibrational spectra of three related network-forming coordination complexes have been studied. Two novel thermodynamically stable pseudo-polymorphic solvated rhodium chloro compounds, [cis-RhCl(4)(DMSO-κS)(2)K](n), 1, and [cis-RhCl(4)(DMSO-κS)(2)K·3H(2)O](n), 2, and one metastable compound [trans-RhCl(4)(DMSO-κS)(2)K·0.25H(2)O](n), 3, crystallize at ambient temperature in the orthorhombic space group P2(1)2(1)2(1) for 1, and the monoclinic space groups P2(1)/n and P2(1)/c for 2 and 3, respectively. All three structures contain [RhCl(4)(DMSO-κS)(2)](-) complexes in which the rhodium(III) ions bind to two dimethyl sulfoxide (DMSO) sulfur atoms and four chloride ions in distorted octahedral coordination geometries. The complexes are connected in networks via potassium ions interacting with the Cl(-) and the DMSO oxygen atoms. As the sum of Shannon ionic radii of K(+) and Cl(-) exceeds the K-Cl distances in compounds under study, these compounds can be described as Rh-Cl-K coordination polymers with non-covalent bonding, which is not common in these systems, forming 1- and 2-D networks for 1/2 and 3, respectively. The 2-D network with nano-layered sheets for compound 3 was also confirmed by TEM images. Further evaluation of the bonding in the cis- and trans-[RhCl(4)(DMSO-κS)(2)](-) entities was obtained by recording Raman and FT-IR absorption spectra and assigning the vibrational frequencies with the support of force-field calculations. The force field study of complexes reveals the strong domination of trans-effect (DMSO-κS > Cl) over the effect of non-covalent bonding in coordination polymeric structures. The comparison of calculated RhCl, RhS and SO stretching force constants showed evidence of K(+)-ligand interactions whereas direct experimental evidences of K(+)-Cl(-) interaction were not obtained because of strong overlap of the corresponding spectral region with that where lattice modes and Rh-ligand bendings appear.