Selçuk Demir

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.

Improving the stability of solar cells using metal–organic frameworks

Although Cu2S-containing chalcogenide solar cells are appealing and cost-effective for photovoltaics (PVs), these materials suffer from rapid performance degradation as a result of the diffusion of copper ions into the CdS layer. In order to prevent this degradation, we report, for the first time, the use of metal–organic frameworks (MOFs) as copper sources. MOFs are a unique class of materials for use in solar cells as they can be tailored to have high porosity in combination with a high density of Lewis basic sites incorporated within the framework backbone. These properties allow for post-metalation reactions to be carried out, which can be exploited for use as copper reservoirs. Experimental evidence shows that the Lewis-basic sites of bipyridine moieties can store copper(I) ions and these ions can be used to compensate for the diffused copper ions leading to an improvement in the stability of prepared Cu2−xS/CdS PV cells. This achievement can ultimately lead to the fabrication of low-cost, long-lived Cu-containing PV cells by using MOFs as supporting materials.

Copper(II) complexes with pyridine-2,6-dicarboxylic acid from the oxidation of copper(I) iodide

Abstract Via an oxidation reaction of Cu(I) iodide with pyridine-2,6-dicarboxylic acid (H2L) in DMF three copper(II) complexes, [(CH3)2NH2]2[CuL2] (1), K2[CuL2]∙H2L∙H2O (2) and [Cu(L)(H2O)]n (3), were synthesized and characterized. The structures of 1–3 were determined by single crystal X-ray diffraction studies. In-situ DMF decomposition produces dimethylamine base under solvothermal conditions and a proton transfer reaction takes place for the complex formation of 1. 3-D networks are stabilized in 1 and 2 via hydrogen bonds. Complex 3 is a 1-D coordination polymer with Cu-O semi-coordination bonds. Thermal decomposition of the complexes results in the corresponding metal oxides. Also, the electrochemical behavior of 1 was determined to be a metal-centered and diffusion-controlled, one-electron reduction process.

A tetranuclear copper (II) complex with pyrazole-3,5-dicarboxylate ligands: synthesis, characterization and electrochemical properties

Abstract A tetranuclear copper (II) complex with pyrazole-3,5-dicarboxylate ligands (pdc3−), [Me2NH2]4[Cu4(pdc)4], was synthesized using solvothermal and metal oxidation routes and characterized by elemental analysis, infrared, thermogravimetry/differential thermal analysis, and room-temperature magnetic measurements. The structure of the complex was determined by single-crystal X-ray diffraction. It comprises dimethylammonium cations and complex anions containing four Cu2+ cations. The crystal structure is stabilized by N–H···O hydrogen bonds. In addition, the electrochemical behavior was studied.

4-Methyl-N-(4-methyl­phenyl­sulfon­yl)-N-phenyl­benzene­sulfonamide

The whole molecule 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-methylphenylsulfonyl groups and by the C atom of the phenyl ring, which is bisected 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 molecules, forming a three-dimensional network.

Synthesis, Crystal Structure, Magnetic, Thermal and Fluorescent Properties of [Co(H2O)4(nia)2](suc)·(H2suc)

A new cobalt(II) complex, [Co(H2O)4(nia)2](suc)·(H2suc) [nicotinamide = nia, succinate = suc2−], has been synthesized and characterized by elemental analysis, IR, TG-DTA and single-crystal X-ray diffraction. It contains [Co(H2O)4(nia)2]2+ complex cations, uncoordinated suc2− anios and H2suc species. In the complex cation the cobalt(II) ion is coordinated by four aqua and two nia ligands in a distorted octahedral geometry. The suc2− dianion acts as a counter-ion, while H2suc is present as a molecule of solvation. A three-dimensional network is formed by O-H· · ·O and N-H· · ·O hydrogen bonds. The title complex exhibits luminescence in the solid state at room temperature. The magnetism of the complex was studied over the temperature range 1.8 - 300 K. Graphical Abstract Synthesis, Crystal Structure, Magnetic, Thermal and Fluorescent Properties of [Co(H2O)4(nia)2](suc)·(H2suc)

Ethene-trans-1,2-bis(4-pyridinium) dihydrogenphosphite and dihydrogenphosphate compounds exhibiting cooperative and directed hydrogen bonds between cations and anions : H2bpe(H2PO3)2 and H2bpe(H2PO4)2·H2O

Abstract H2bpe(H2PO3)2 (1) and H2bpe(H2PO4)2 ・H2O (2) (H2bpe = ethene-trans-1,2-bis(4-pyridinium), H2PO3 = dihydrogenphosphite, and H2PO4 = dihydrogenphosphate) have been prepared and structurally characterized. In compound 1, the dihydrogenphosphite anions form dimers, with a P···P distance of 4.2073(7) Å , by two O-H···H hydrogen bonds, and the dimeric dihydrogenphosphite units interact with the H2bpe cations by way of N-H···O and O-H···O hydrogen bonds, resulting in a one-dimensional chain. The chains are held together by C-H···O interactions. In compound 2, the phosphate ions are connected by O-H···O hydrogen bonds into an unusual 2D square gridtype framework with P···P separations ranging from 4.7533(7) to 4.9506(8) Å . The H2bpe cations crosslink the dihydrogen phosphate layers by N-H···O hydrogen bonds, forming a three-dimensional supramolecular network with channels. The water molecules in compound 2 occupy these channels and make O-H···O bonds to adjacent phosphate O atoms and also O-H···O bonds to the next water O atom in the channel.