Dual-Ligand Strategy for the Design and Construction of a Cd-Zn Heterometallic Metal-Organic Framework by One-Pot Synthesis as a Heterogeneous Catalyst for the Epoxidation Reaction of Olefins.

The use of metal-organic frameworks (MOFs) as catalysts is reported in various industrial applications. In contrast to monometallic MOFs, heterometallic MOFs with mixed organic ligands showed enhanced catalytic properties. The catalytic properties of heterometallic MOFs can be enhanced by generating defects and the synergistic effect between the two heterometals at secondary building units. By using a solvothermal technique, a Cd-Zn heterometallic MOF with a new morphology, [Cd2Zn(DPTTZ)0.5(OBA)3(H2O)(HCOOH)] (IUST-4) [DPTTZ = 2,5-di(4-pyridyl)thiazolo[5,4-d]thiazole, OBA = 4,4'-oxybis(benzoic acid)], was synthesized via a mixed-ligand strategy and characterized by single-crystal and powder X-ray diffraction, Fourier transform infrared spectroscopy, elemental analysis, and thermogravimetric analysis. X-ray crystallographic analysis showed that IUST-4 is a neutral 3D metal-organic framework crystallized in the monoclinic system with space group C2/c. In this study, the catalytic properties of IUST-4 for the epoxidation of cyclooctene were investigated. IUST-4 was selected as the optimal catalyst for epoxy product production due to its high selectivity and yield. Moreover, the catalytic performance of IUST-4 was maintained despite five recycling cycles without significant degradation. The epoxidation of cyclooctene with IUST-4 has several advantages, including good selectivity, easy recovery, and short-time reaction.

Enhanced CO2 capture potential of UiO-66-NH2 synthesized by sonochemical method: experimental findings and performance evaluation.

The excessive release of greenhouse gases, especially carbon dioxide (CO2) pollution, has resulted in significant environmental problems all over the world. CO2 capture technologies offer a very effective means of combating global warming, climate change, and promoting sustainable economic growth. In this work, UiO-66-NH2 was synthesized by the novel sonochemical method in only one hour. This material was characterized through PXRD, FT-IR, FE-SEM, EDX, BET, and TGA methods. The CO2 capture potential of the presented material was investigated through the analysis of gas isotherms under varying pressure conditions, encompassing both low and high-pressure regions. Remarkably, this adsorbent manifested a notable augmentation in CO2 adsorption capacity (3.2 mmol/g), achieving an approximate enhancement of 0.9 mmol/g, when compared to conventional solvothermal techniques (2.3 mmol/g) at 25 °C and 1 bar. To accurately represent the experimental findings, three isotherm, and kinetic models were used to fit the experimental data in which the Langmuir model and the Elovich model exhibited the best fit with R2 values of 0.999 and 0.981, respectively. Isosteric heat evaluation showed values higher than 80 kJ/mol which indicates chemisorption between the adsorbent surface and the adsorbate. Furthermore, the selectivity of the adsorbent was examined using the Ideal Adsorbed Solution Theory (IAST), which showed a high value of 202 towards CO2 adsorption under simulated flue gas conditions. To evaluate the durability and performance of the material over consecutive adsorption-desorption processes, cyclic tests were conducted. Interestingly, these tests demonstrated only 0.6 mmol/g capacity decrease for sonochemical UiO-66-NH2 throughout 8 consecutive cycles.

Fabrication and characterization of a novel catalyst based on modified zirconium metal-organic-framework for synthesis of polyhydroquinolines.

A novel catalyst was fabricated in this study based on zirconium MOF modified with pyridine carboxaldehyde in a solvothermal reaction, embedded with cerium. In order to confirm the catalyst structure, various characterization techniques, including FTIR, Far IR, EDX, XRD, TGA, FE-SEM, ICP, and BET analyses, were employed. The results indicated that the UiO-66-Pyca-Ce (III) catalyst had a Langmuir surface area of 501.63 m2/g, a pore volume of 0.28 cm3/g, and a pore size of 2.27 nm. To study catalytic activity, a sequential approach of Knoevenagel condensation and Michael addition was used to synthesize various polyhydroquinoline derivatives. The reaction took place at ambient temperature. The UiO-66-Pyca-Ce (III) catalyst demonstrated high efficacy (90%) and reusability in asymmetric synthesis of polyhydroquinoline derivatives for several reasons, including the possession of three Lewis acid activation functions.

Novel magnetic nanocomposites BiFeO3/Cu(BDC) for efficient dye removal.

In this study, bismuth ferrite nanoparticles and metal-organic framework, Cu(BDC), were prepared by microwave-assisted combustion in solid state and ultrasound-assisted method, respectively. To enhance the properties of bismuth ferrite nanoparticles and Cu(BDC), we form them as their composite through microwave and ultrasonic probe strategies. Various analyses, including FT-IR, XRD, SEM, DRS, VSM, and so on, were applied to verify the synthesis accuracy. Then, the catalytic performances of the nanoparticles and the as-prepared nanocomposites were evaluated through photocatalytic degradation of methyl orange. Furthermore, the adsorption capacity of the as-synthesized materials was assessed toward the Congo red removal from wastewater. All the results prove that the proposed nanocomposite can be an acceptable candidate for eliminating contaminants from wastewater. The electrochemical properties of bismuth ferrite, BiFeO3/Cu(BDC) nanocomposite 1, and BiFeO3/Cu(BDC) nanocomposite 2 have been studied by cyclic voltammetry.

Amino-induced cadmium metal-organic framework based on thiazole ligand as a heterogeneous catalyst for the epoxidation of alkenes.

Selective epoxidation of olefins is of high interest in the chemical industry due to the many applications of epoxides. This study reports on the synthesis of Cd-MOF, [Cd(DPTTZ)(5-AIP)] (IUST-1) (where DPTTZ = 2, 5-di (pyridine-4-yl) thiazolo [5, 4-d] thiazole, 5-AIP = 5-Aminoisophthalic acid), by a reflux method, which can be considered as a fast and simple process. The morphology and structure of the synthesized IUST-1 were determined by using FE-SEM (Field Emission Scanning Electron Microscopy), EDX (Energy Dispersive Analysis of X-ray), Mapping (Elemental Mapping), CHNS (Elemental analysis), XRD (X-Ray Diffraction), FT-IR (Fourier Transform Infrared), and TGA (Thermo Gravimetric Analysis). The epoxidation of cyclooctene was investigated using the activity of catalytic IUST-1. The results showed that in the presence of tert-butyl hydroperoxide and CCl4 in a 1:2 alkene/oxidant ratio, a high epoxide yield (99.8%) was obtained. In addition, IUST-1 can be easily separated by simple filtration and recycled five times successfully with a slight decrease in activity. This compound has some advantages such as high yield, short reaction time, and ease of reuse, which make it a suitable heterogeneous catalyst for the epoxidation of cyclooctene.

Novel Zn metal-organic framework with the thiazole sites for fast and efficient removal of heavy metal ions from water.

Pollution of water by heavy metal ions such as Pb2+ and Hg2+ is considered as an important issue, because of the potential toxic effects these ions impose on environmental ecosystems and human health. A new Zn-based metal-organic framework, [Zn2(DPTTZ) (OBA)2] (IUST-2), was synthesized through a solvothermal method by the reaction of 2, 5-di (4- pyridyl) thiazolo [5, 4-d] thiazole ligand (DPTTZ), the "V-shape" 4,4'-oxybis (benzoic acid) ligand (OBA) and zinc nitrate (Zn(NO3)2·6H2O). This novel MOF has been characterized by several analysis techniques such as fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), powder x-ray diffraction (PXRD), thermogravimetry analysis (TGA), differential thermal analysis (DTA), field emission scanning electron microscopy (FE-SEM), Brunauer-Emmett-Teller (BET) surface area analysis and single-crystal X-ray diffraction (SXRD). This 3D MOF was tested for removing Pb2+ and Hg2+ ions from water. The factors that were investigated on the elimination of Pb2+ and Hg2+ ions were of pH, adsorption time, and the effect of initial ions concentration. According to the results, this particular Zn-MOF had significant performance in eliminating Pb2+ and Hg2+ ions from water with a removal efficiency of more than 97% and 87% within 3 min, respectively.

Synthesis of UiO-66-Sal-Cu(OH)2 by a Simple and Novel Method: MOF-Based Metal Thin Film as a Heterogeneous Catalyst for Olefin Oxidation.

Metal-organic frameworks (MOFs), particularly UiO-66-NH2, are employed as a catalyst in many industrial catalyst applications. As converting catalysts into thin film significantly increases their catalytic properties for the epoxidation of olefins, we report a general approach to synthesizing MOF thin films (UiO-66-Sal-Cu(OH)2). Using the postsynthesis method (PSM), UiO-66-NH2 was functionalized with salicylaldehyde and entrapped on copper hydroxide nanoparticle surfaces using a modern strategy (MOF thin film). We used field-emission scanning electron microscopy (FE-SEM), EDX (energy-dispersive X-ray analysis), XRD (X-ray diffraction), FT-IR (Fourier transform infrared), BET (Brunauer-Emmett-Teller), TGA (thermogravimetric analysis), XPS (X-ray photoelectron spectroscopy), and ICP-MS (inductively coupled plasma mass spectrometry) to determine the structure and morphology of the synthesized UiO-66-Sal-Cu(OH)2. The oxidation of cyclooctene by the UiO-66-Sal-Cu(OH)2 thin film was studied. Due to its advantages, such as being environmentally friendly (base metal-loaded catalyst, room temperature, solvent-free reaction), reusability, and high yield, this compound can be an appropriate catalyst for the oxidation of olefins.

Luminescent Cd coordination polymer based on thiazole as a dual-responsive chemosensor for 4-nitroaniline and CrO42- in water.

A novel highly fluorescent cadmium metal-organic framework, [Cd (DPTTZ) (OBA)] (IUST-3), synthesized by using two linkers 2, 5-di (pyridine-4-yl) thiazolo [5, 4-d] thiazole (DPTTZ) and 4, 4'-oxybis (benzoic acid) (OBA) simultaneously, which exhibits a two-dimensional framework. The characteristics of this Cd-MOF were investigated by single-crystal X-ray diffraction, Fourier transform infrared spectroscopy, elemental analysis, powder X-ray diffraction, and thermogravimetry analysis. The IUST-3 exhibits excellent luminescence property and good stability in water. Luminescent experiments indicate that the IUST-3 has remarkable sensitivity and selectivity for the detection of 4-nitroaniline (4-NA), and CrO42- anion with KSV = 1.03 × 105 M-1 (4-NA) and KSV = 2.93 × 104 M-1 (CrO42-) and low limit of detection 0.52 µM (4-NA) and 1.37 µM (CrO42-). In addition, the possible fluorescence quenching mechanism was explored in this paper.

Low molecular weight chitosan-cyanocobalamin nanoparticles for controlled delivery of ciprofloxacin: Preparation and evaluation.

This study was carried out to project a safe nano-drug carrier composed of chitosan and cyanocobalamin (CNCbl) to improve oral delivery of ciprofloxacin hydrochloride (CIP). CIP is classified in class IV of the biopharmaceutical classification system with low solubility and permeabilityA, so it has some problems if given orally. Novel conjugate of low molecular weight chitosan, as a natural biopolymer, and CNCbl was synthesized, and then drug loading and in-vitro drug release were assessed. The loading of CIP was optimized by the Design-Expert software and the central composite design method, and that the optimal drug loading efficiency (57%) was obtained via analysis of variance (ANOVA). In-vitro drug release studies showed controlled release patterns in two various conditions, namely phosphate buffer saline (pH = 7.4) and 0.1 N HCl. Functionalized nano-drug-loaded carrier showed cytotoxicity as much as that of free drug, particle size less than 100 nm as well as positive zeta potential. Due to the beneficial properties of the chitosan-based drug carrier and the suitable features of the CIP-loaded carrier, this chitosan-based nano-drug delivery system can be regarded as an ideal candidate for oral delivery of the CIP as a drug model.

Synthesis and Characterization of Magnetic Zeolite Y-Palladium-Nickel Ferrite by Ultrasonic Irradiation and Investigating Its Catalytic Activity in Suzuki-Miyaura Cross-Coupling Reactions.

Zeolite faujasite is widely used as a catalyst in many industrial catalytic applications. In this study, synthesis and characterization of magnetic zeolite Y-palladium-nickel ferrite were studied. First, palladium nanoparticles were combined with nickel ferrite and then placed on zeolite Y by ultrasonic treatment. The structure and morphology of the synthesized magnetic zeolite Y-palladium-nickel ferrite were characterized using Fourier transform infrared, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray, vibrating sample magnetometer, and inductively coupled plasma optical emission spectroscopy analysis. Also, we investigated the catalytic activity of this prepared zeolite in Suzuki-Miyaura coupling reaction between phenylboronic acid and aryl halides. Our study shows that magnetic zeolite Y-palladium-nickel ferrite is a suitable catalyst for Suzuki-Miyaura coupling reaction. Short reaction time, high yield, and easy reusability are the advantages of using this catalyst in carbon-carbon cross-coupling reactions.

Highly efficient ultrasonic-assisted removal of Hg(II) ions on graphene oxide modified with 2-pyridinecarboxaldehyde thiosemicarbazone: Adsorption isotherms and kinetics studies.

A novel adsorbent, based on modifying graphene oxide (GO) chemically with 2-pyridinecarboxaldehyde thiosemicarbazone (2-PTSC) as ligand, was designed by facile process for removal of Hg(II) from aqueous solution. Characterization of the adsorbent was performed using various techniques, such as FT-IR, XRD, XPS, SEM and AFM analysis. The adsorption capacity was affected by variables such as adsorbent dosage, pH solution, Hg(2+) initial concentration and sonicating time. These variables were optimized by rotatable central composite design (CCD) under response surface methodology (RSM). The predictive model for Hg(II) adsorption was constructed and applied to find the best conditions at which the responses were maximized. In this conditions, the adsorption capacity of this adsorbent for Hg(2+) ions was calculated to be 309mgg(-1) that was higher than that of GO. Appling the ultrasound power combined with adsorption method was very efficient in shortening the removal time of Hg(2+) ions by enhancing the dispersion of adsorbent and metal ions in solution and effective interactions among them. The adsorption process was well described by second-order kinetic and Langmuir isotherm model in which the maximum adsorption capacity (Qm) was found to be 555mgg(-1) for adsorption of Hg(2+) ions over the obtained adsorbent. The performance of adsorbent was examined on the real wastewaters and confirmed the applicability of adsorbent for practical applications.

Highly efficient simultaneous ultrasonic-assisted adsorption of Pb(II), Cd(II), Ni(II) and Cu (II) ions from aqueous solutions by graphene oxide modified with 2,2'-dipyridylamine: Central composite design optimization.

In present work, a graphene oxide chemically modified with 2,2'-dipyridylamine (GO-DPA), was synthesized by simple, fast and low-cost process for the simultaneous adsorption of four toxic heavy metals, Pb(II), Cd(II), Ni(II) and Cu(II), from aqueous solutions. The synthesized adsorbent was characterized by FT-IR, XRD, XPS, SEM and AFM measurements. The effects of variables such as pH solution, initial ion concentrations, adsorbent dosage and sonicating time were investigated on adsorption efficiency by rotatable central composite design. The optimum conditions, specified as 8mg of adsorbent, 20mgL(-1) of each ion at pH 5 and short time of 4min led to the achievement of a high adsorption capacities. Ultrasonic power had important role in shortening the adsorption time of ions by enhancing the dispersion of adsorbent in solution. The adsorption kinetic studies and equilibrium isotherms for evaluating the mechanism of adsorption process showed a good fit to the pseudo-second order and Langmuir model, respectively. The maximum adsorption capacities (Qm) of this adsorbent were 369.749, 257.201, 180.893 and 358.824mgg(-1) for lead, cadmium, nickel and copper ions, respectively. The removal performance of adsorbent on the real wastewater samples also showed the feasibility of adsorbent for applying in industrial purposes.

Solid phase extraction of Cd(II) and Pb(II) ions based on a novel functionalized Fe3O4@ SiO2 core-shell nanoparticles with the aid of multivariate optimization methodology.

This work describes novel Fe3O4@SiO2 core-shell nanoparticles functionalized with phenyl isothiocyanate and its application in the preconcentration of Cd(II) and Pb(II) ions. The parameters affecting the preconcentration procedure were optimized by a Box-Behnken design through response surface methodology. Three variables (extraction time, magnetic sorbent amount, and pH value) were selected as the main factors affecting the sorption step, while four variables (type, volume and concentration of the eluent; and elution time) were selected as effective factors of elution step in the optimization study. Following the sorption and elution, the ions were quantified by FAAS. The limits of detection were 0.05 and 0.9ngmL(-1) for Cd(II) and Pb(II) ions, respectively. The relative standard deviations were less than 6.4%. The sorption capacity (in mg g(-1)) of this new sorbent is 179 for Cd(II) and 156 for Pb(II). Finally, this nanocomposite was successfully applied to the rapid extraction of trace quantities of heavy metal ions from fish, sediment, soil, and water samples and satisfactory results were obtained.

A novel electrochemical sensor based on metal-organic framework for electro-catalytic oxidation of L-cysteine.

A novel electrochemical sensor based on Au-SH-SiO2 nanoparticles supported on metal-organic framework (Au-SH-SiO2@Cu-MOF) has been developed for electrocatalytic oxidation and determination of L-cysteine. The Au-SH-SiO2@Cu-MOF was characterized by scanning electron microscopy, transmission electron microscopy, x-ray diffraction and cyclic voltammetry. The electrochemical behavior of L-cysteine at the Au-SH-SiO2@Cu-MOF was investigated by cyclic voltammetry. The Au-SH-SiO2@Cu-MOF showed a very efficient electrocatalytic activity for the oxidation of L-cysteine in 0.1 M phosphate buffer solution (pH 5.0). The oxidation overpotentials of L-cysteine decreased significantly and their oxidation peak currents increased dramatically at Au-SH-SiO2@Cu-MOF. The potential utility of the sensor was demonstrated by applying it to the analytical determination of L-cysteine concentration. The results showed that the electrocatalytic current increased linearly with the L-cysteine concentration in the range of 0.02-300 µM and the detection limit was 0.008 µM. Finally, the sensor was applied to determine L-cysteine in water and biological samples.

Fabrication of a PVC membrane samarium(III) sensor based on N,N',N"-tris(4-pyridyl)trimesic amide as a selectophore.

A new ion-selective electrode for Sm(3+) ion is described based on the incorporation of N,N',N"-tris(4-pyridyl)trimesic amide (TPTA) in a poly(vinylchloride) (PVC) matrix. The membrane sensor comprises nitrobenzene (NB) as a plasticizer, and oleic acid (OA) as an anionic additive. The sensor with the optimized composition shows a Nernstian potential response of 19.8 ± 0.5 mV decade(-1) over a wide concentration range of 1.0 × 10(-2) and 1 × 10(-6)mol L(-1), with a lower detection limit of 4.7 × 10(-7)mol L(-1) and satisfactor applicable pH range of 3.6-9.2. Having a short response time of less than 10s and a very good selectivity towards the Sm(3+) over a wide variety of interfering cations (e.g. alkali, alkaline earth, transition and heavy metal ions) the sensor seemed to be a promising analytical tool for determination of the Sm(3+). Hence, it was used as an indicator electrode in the potentiometric titration of samarium ion with EDTA. It was also applied to the direct samarium recovery in binary mixtures.

(Acetato-κ(2)O,O')(acetato-κO)bis(2-amino-3-methyl-pyridine-κN(1))cobalt(II).

In the title compound, [Co(CH(3)COO)(2)(C(6)H(8)N(2))(2)], the Co(II) ion is five-coordinated by two pyridine N atoms from two 2-amino-3-methyl-pyridine ligands, two O atoms from one acetate ion and one O atom from another acetate ion in a distorted trigonal-bipyramidal geometry. The pyridine rings are nearly perpendicular to each other [dihedral angle = 84.49 (16)°]. The crystal packing is stabilized by intra-molecular and inter-molecular N-H⋯O hydrogen-bonding inter-actions.

Di-µ-chlorido-bis-[(2-amino-4-methyl-pyridine-κN)-chloridomercury(II)].

In the centrosymmetric dinuclear title compound, [Hg(2)Cl(4)(C(6)H(8)N(2))(2)], the Hg(II) ion is four-coordinated by one pyridine N atom from a 2-amino-4-methyl-pyridine ligand, one terminal Cl atom and two bridging Cl atoms. A distorted tetra-hedral geometry is formed around each Hg(II) ion. The crystal packing is stabilized by intra- and inter-molecular N-H⋯Cl hydrogen bonding. There are also π-π stacking inter-actions in the structure, with centroid-to-centroid distances of 3.594 (6) Å.

Bis(2-amino-3-methyl-pyridine-κN(1))dichloridomercury(II).

In the title compound, [HgCl(2)(C(6)H(8)N(2))(2)], the two independent Hg(II) cations are each located on a twofold rotation axis and coordinated by two pyridine N atoms from two 2-amino-3-methyl-pyridine ligands and two Cl(-) anions in a distorted tetra-hedral geometry. An intra-molecular N-H⋯Cl hydrogen bond occurs in each independent complex mol-ecule. Inter-molecular N-H⋯Cl hydrogen bonds occur in the crystal structure.

Dibromido(2,9-dimethyl-1,10-phenanthroline-κ(2)N,N')zinc.

The reaction of equimolar amounts of zinc bromide and 2,9-dimethyl-1,10-phenanthroline in dry methanol provided the title compound, [ZnBr(2)(C(14)H(12)N(2))], in good yield. The Zn(II) ion is coordinated in a distorted tetra-hedral environment by two N atoms from the chelating 2,9-dimethyl-1,10-phenanthroline ligand and two bromide ions. There is inter-molecular π-π stacking between adjacent phenanthroline units, with centroid-centroid distances of 3.594 (3) and 3.652 (3) Å.

Bis(2-amino-3-methyl-pyridine)-dichlorido-cobalt(II).

In the title compound, [CoCl(2)(C(6)H(8)N(2))(2)], the Co(II) ion is four-coordinated by two pyridine N atoms from the 2-amino-3-methyl-pyridine ligands and two chloride ions in a distorted tetra-hedral geometry. A weak intra-molecular N-H⋯Cl inter-action occurs. The crystal packing is stabilized by inter-molecular N-H⋯Cl and C-H⋯Cl hydrogen-bond inter-actions.