A zirconium metal-organic framework functionalized with a S/N containing carboxylic acid (MOF-808(Zr)-Tz) as an efficient sorbent for the ultrafast and selective dispersive solid phase micro extraction of chromium, silver, and rhodium in water samples.

Metal-organic frameworks (MOFs) are good adsorbents for targeted chemicals with their adjustable properties. Herein, we prepared a zirconium based MOF (MOF-808(Zr)) and functionalized it employing 2-mercapto-4-methyl-5-thiazolacetic acid (MOF-808(Zr)-Tz). The prepared MOFs were characterized by XRD, FTIR, SEM-EDX, TGA, N2 sorption, zeta potential measurements, and elemental analysis. The surface area of MOF-808(Zr)-Tz was 1348 m2/g. Dispersive solid-phase micro-extraction (D-SPµE) method based on MOF-808(Zr)-Tz was firstly developed and applied to the extraction of chromium, silver, and rhodium in waters. The determination of the analytes was done by FAAS. The optimal pH and eluent for analytes were 7.0 and 3 mL of 2 mol L-1 HCl, respectively. The contact times were 1 min for adsorption and 3 min for elution. The LOD and PFs of the D-SPµE for analytes were 2.3 µg L-1 and 13.3 for chromium, 2.1 µg L-1 and 13.3 for silver, and 3.1 µg L-1 and 13.3 rhodium, respectively. The D-SPµE method was verified with analyses of NW-TMDA-54.6 Lake water and SPS-WW1 Batch 114 Wastewater and with spiked dam water, river water, well water, sea water, and wastewater. The recoveries of the analytes changed from 89 to 108 %. The results indicated that the method is selective, simple, effective, and rapid for extracting chromium(III), silver(I) and rhodium(III) in waters.

Enhanced water stability and high CO2 storage capacity of a Lewis basic sites-containing zirconium metal-organic framework.

Metal-organic frameworks (MOFs) are an emerging class of materials employed for custom-designed purposes by judicious selection of linkers and metal ions. Among the MOFs composed of carboxylate linkers, Zr-based MOFs have attracted great attention due to their high thermal and chemical stabilities, which are important for practical applications, including capturing CO2 from a point source. UiO-67(bipy) containing 2,2'-bipyridine-5,5'-dicarboxylate is particularly useful among the Zr-MOF family due to the Lewis basic sites of the linker; however, the hydrolytic stability of UiO-67(bipy) does not seem to be as high as those of UiO-66 and UiO-67. To improve the hydrolytic stability without sacrificing the adsorption enthalpy of CO2 for selective CO2 capture, in this study, we added hydrophobic methyl groups to the backbone of the bipyridine linker. The synthesized 6,6'-dimethyl-2,2'-bipyridine-5,5'-dicarboxylic acid (H2Me2bipy) was used to prepare a Zr-based MOF [MOF-553, Zr6O4(OH)4(Me2Bipy)6]. In addition, the water stability and CO2 adsorption capacity of MOF-553 were compared to those of UiO-67(bipy). We revealed that MOF-553 is more robust and has a higher CO2 adsorption capacity than UiO-67(bipy), indicating that the methylation of the linker improves the water stability of the framework, which is advantageous for point-source CO2 capture.

Determination of color additive tartrazine (E 102) in food samples after dispersive solid phase extraction with a zirconium-based metal-organic framework (UiO-66(Zr)-(COOH)2).

A new and rapid dispersive solid phase extraction method by using a green-synthesised UiO-66(Zr)-(COOH)2 (Zr-BTeC) adsorbent with body-centred cubic (bcu) topology was developed for determination of tartrazine in food samples. Zr-BTeC was used for the first time as an adsorbent for tartrazine. It was synthesised and characterised by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, Brunauer-Emmett-Teller surface area analysis, and zeta potential measurements. Tartrazine was determined at 405 nm spectrophotometrically. Experimental conditions were optimised in order to achieve quantitative recoveries. The sample acidity was found to be 0.02 mol L-1 HCl. The amount of Zr-BTeC was 10 mg. Both adsorption and elution contact times were only 5 s without the need for vortexing. Elution was with 2 mL of 0.5 mol L-1 NH3. A sample volume of 45 mL was selected as optimum. The adsorption capacity for tartrazine with Zr-BTeC was found to be 185 mg g-1 and the adsorbent was reusable up to 40 cycles. The tartrazine concentrations found by the developed method in food supplements were compared with the results obtained by HPLC method for the same samples. Statistical analysis results showed that there are insignificant differences between the results of the two methods (p = .05). The method was successfully applied to the determination of tartrazine in spiked chewing gums, lemon flavoured icing glaze, and jelly samples.

Zirconium-based highly porous metal-organic framework (MOF-545) as an efficient adsorbent for vortex assisted-solid phase extraction of lead from cereal, beverage and water samples.

In this study, zirconium-based highly porous metal-organic framework, MOF-545, was synthesized and characterized. The surface area of MOF-545 was found to be 2192m2/g. This adsorbent was used for the first time as an adsorbent for the vortex assisted-solid phase extraction of Pb(II) from cereal, beverage and water samples. Lead in solutions was determined by FAAS. The optimal experimental conditions were as follows: the amount of MOF-545, 10mg; pH of sample, 7; adsorption and elution time, 15min; and elution solvent, 2mL of 1molL-1HCl. Under the optimal conditions of the method, the limit of detection, preconcentration factor and precision as RSD% were found to be 1.78µgL-1, 125 and 2.6%, respectively. The adsorption capacity of the adsorbent for lead was found to be 73mgg-1. The method was successfully verified by analyzing two certified reference materials (BCR-482 Lichen and SPS-WW1 Batch 114) and spiked chickpea, bean, wheat, lentil, cherry juice, mineral water, well water and wastewater samples.

4-Methyl-N-(4-methyl-phenyl-sulfon-yl)-N-phenyl-benzene-sulfonamide.

The whole mol-ecule of the title compound, C20H19NO4S2, is generated by twofold rotational symmetry. The N atom is located on the twofold rotation axis and has a trigonal-planar geometry. It is bonded by two S atoms of two symmetry-related 4-methyl-phenyl-sulfonyl groups and by the C atom of the phenyl ring, which is bis-ected by the twofold rotation axis. The benzene and phenyl rings are oriented at a dihedral angle of 51.48 (5)° while the pendant benzene rings are inclined to one another by 87.76 (9)°. In the crystal, weak C-H⋯O hydrogen bonds link the mol-ecules, forming a three-dimensional network.

Synthesis, structure, and metalation of two new highly porous zirconium metal-organic frameworks.

Three new metal-organic frameworks [MOF-525, Zr(6)O(4)(OH)(4)(TCPP-H(2))(3); MOF-535, Zr(6)O(4)(OH)(4)(XF)(3); MOF-545, Zr(6)O(8)(H(2)O)(8)(TCPP-H(2))(2), where porphyrin H(4)-TCPP-H(2) = (C(48)H(24)O(8)N(4)) and cruciform H(4)-XF = (C(42)O(8)H(22))] based on two new topologies, ftw and csq, have been synthesized and structurally characterized. MOF-525 and -535 are composed of Zr(6)O(4)(OH)(4) cuboctahedral units linked by either porphyrin (MOF-525) or cruciform (MOF-535). Another zirconium-containing unit, Zr(6)O(8)(H(2)O)(8), is linked by porphyrin to give the MOF-545 structure. The structure of MOF-525 was obtained by analysis of powder X-ray diffraction data. The structures of MOF-535 and -545 were resolved from synchrotron single-crystal data. MOF-525, -535, and -545 have Brunauer-Emmett-Teller surface areas of 2620, 1120, and 2260 m(2)/g, respectively. In addition to their large surface areas, both porphyrin-containing MOFs are exceptionally chemically stable, maintaining their structures under aqueous and organic conditions. MOF-525 and -545 were metalated with iron(III) and copper(II) to yield the metalated analogues without losing their high surface area and chemical stability.

Experimental and theoretical study on the structure and vibrational spectra of ß-2-aminopyridinium dihydrogenphosphate.

Experimental and theoretical vibrational spectra of ß-2-aminopyridinium dihydrogenphosphate (ß-2APDP) have been investigated. The FT-IR spectrum of ß-2APDP was recorded in the region 4000-400 cm(-1). The optimized molecular structure and theoretical vibrational frequencies of ß-2APDP have been investigated using ab initio Hartree-Fock (HF) and density functional B3LYP method with 6-311++G(d,p) basis set. The optimized geometric parameters (bond lengths and bond angles) and theoretical frequencies have been compared with the corresponding experimental data and it is found that they agree well with each other. All the assignments of the theoretical frequencies were performed by potential energy distributions using VEDA 4 program. Furthermore, the used scale factors were obtained from the ratio of the frequency values of the strongest peaks in the experimental and theoretical IR spectra. From the results it was concluded that the B3LYP method is superior to the HF method for the vibrational frequencies.

A second polymorph of 2-aminopyridinium dihydrogenphosphate.

In the title compound, beta-C5H7N2+.H2PO4-, the tetrahedral dihydrogenphosphate moieties are linked into double chains by O-H...O hydrogen bonds, and the organic species crosslink the chains into sheets by way of N-H...O bonds. The resulting structure is quite different from that of the previously described alpha polymorph of this stoichiometry [Czapla, Dacko & Waskowska (2003). J. Phys. Condens. Matter, 15, 3793-3803].

2-(hydroxymethyl)pyridinium dihydrogenphosphate.

The title compound, C(6)H(8)NO(+).H(2)PO(4)(-), consists of 2-(hydroxymethyl)pyridinium and dihydrogenphosphate ions. The dihydrogenphosphate moieties are linked into chains by pairs of P-O-H.O-P hydrogen bonds. The 2-(hydroxymethyl)pyridinium cations are connected to the dihydrogenphosphate units by O-H.O and N-H.O hydrogen bonds. Weak pi-pi interactions help to determine the interchain packing.

N-(2-hydroxyethyl)ethylenediammonium hydrogenphosphate monohydrate.

The title compound, C(4)H(14)N(2)O(2+) x HPO(4)(2-) x H(2)O, contains alternating interleaved layers of hydrogenphosphate and N-(2-hydroxyethyl)ethylenediammonium moieties. The water molecules are associated with channel-like voids in the structure and a network of hydrogen bonds stabilizes the crystal packing.