A fluorescence chemosensor for benzonitrile derived from in-situ synthesis of azolate–carboxylic acid and zinc(II) ions

A new zinc(II) homometallic coordination polymer (CP), {[Zn(TAA-OH)₂] · 1.5H₂O}_n (1) (HTAA-OH = 2-(5-hydroxy-1H-1,2,4-triazole-1-yl) acetic acid) has been synthesized via an in-situ synthetic approach and structurally characterized in detail. In 1, the HTAA-OH ligand is generated in-situ by the nucleophilic addition of 2-(1H-1,2,4-triazole-1-yl) acetic acid. CP 1 features a 2D structure with sql topology, where the neighboring Zn(II) ions are bridged through two oxygen atoms of carboxyl group and two nitrogen atoms of triazole from the HTAA-OH ligands. Luminescence study shows that 1 dispersed in acetonitrile performs a distinct luminescence enhancing effect upon addition of benzonitrile, indicating that 1 is a promising fluorescence chemosensor for benzonitrile.     

A novel chelate-assisted C−C bond formation on a Cd(II) complex of an asymmetric heptadentate(N7) tripodal Schiff base ligand

Cadmium(II) complexes of some potentially heptadentate tripodal Schiff base ligands with the general formula N{(CH₂)_nNCHC₅H₄N}₂{(CH₂)_mNCHC₅H₄N}) (where n = m = 2, L₂₂₂; n = 2, m = 3, L₃₂₂; n = 3, m = 2, L₃₃₂) have been studied. These ligands are products of the full condensation of a number of tripodal tetraamines with 2-pyridinecarboxaldehyde. An unusual reaction of an additional 2-pyridine-carboxaldehyde with a methylene group adjacent to the imine bond only during template preparation of [Cd(L₃₃₂)]²⁺ was observed. The latter reaction is a novel chelate-assisted C?C bond formation because it is occurred only where a rigid five-membered chelate ring is present.     

Tris(N,N′-dimethylurea)bis(nitrato-O,O′)manganese(II), the first example of a seven-coordinate manganese(II) complex with a monodentate organic ligand

Employing a variety of solvents and molar ratios, the reactions of Mn(NO₃)₂·6H₂O with N,N′-dimethylurea (DMU) afforded the adduct [Mn(NO₃)₂(DMU)₃] (1). X-ray analysis shows that the high-spin complex has a pentagonal bipyramidal geometry with two DMU oxygen atoms in axial positions and with two types of monodentate O-bonding for the DMU molecules, one of them being very unusual. The spectroscopic properties of the prepared complex are also discussed.     

Synthesis,X-ray structure and catalytic properties of a copper(II) Schiff base complex modeling the activity of the CuB site of dopamine β-hydroxylase

The copper(II) complex [Cu(salgly)(bpy)]·4H₂O (1), where salgly is a tridentate glycinatosalicylaldimine Schiff base ligand, is prepared and structurally characterized. The complex is found to be catalytically active in the oxidation of ascorbic acid by dioxygen and the process is also effective in the presence of benzylamine giving benzaldehyde as a product, thus modeling the activity of the Cu_B site of dopamine β-hydroxylase.     

Uptake of copper (II) ions from acidic aqueous solutions using a continuous column packed with microcapsules containing a β-hydroxyoximic compound

In this paper, the uptake of Cu(II) ions from an acidic aqueous solution using a continuous column packed with microcapsules containing the chelating extractant LIX-860 N-IC was examined. A simple, economical method was employed to synthesise the microcapsules’ polymeric matrix consisting of an in situ radical polymerisation method followed by the subsequent impregnation of the extractant compound 5-nonylsalicylaldoxime. The microcapsules had a spherical shape with a rough surface and a strong hydrophobic character that assured that the organic extractant was immobilised on the microspheres’ porous structure. During the metal sorption experiments, three different columns were used, and the aqueous feed solution circulated through them at different flow rates in repetitive sorption-desorption cycles. The results of these experiments revealed that the metal extractability was improved when the flow rate of the feed phase decreased and when the largest column was used, likely because of the higher residence time of the solution in the column improving the solution's contact with the microcapsules and also because of an increase in the vacant sites for the sorption process.The experimental data of the metal sorption onto the microcapsules in the fixed bed columns were explained by three different models (Wang, Thomas and dose-response). In general, the three predictive equations fit the dynamic behaviour of the breakthrough curves well. However, the modified dose-response model correlated better with the experimental data than the other model equations, as shown by the statistical parameters determined from the experimental conditions used.     

Synthesis and evaluation of a ruthenium–copper oxide/silica catalyst derived from microemulsion processing

Bimetallic Ru–Cu catalysts supported on SiO₂ have been synthesized in microemulsions using sodium metasilicate (Na₂SiO₃), copper nitrate (Cu(NO₃)_2·3H₂O) and ruthenium chloride (RuCl₃) at 28 °C. The microemulsion system consists of sodium 1,4‐bis(2‐ethylhexyl) sulfosuccinate (AOT) and sodium dodecyl sulphate (SDS), cyclohexane, and an aqueous solution of sodium metasilicate or metal salts. The catalysts have been characterized by XPS, EDX/SEM with line scanning and they possess a very narrow pore size distribution (around 38 Å) and relatively high specific surface areas (around 400 m²/g). The catalytic results of the N₂O decomposition reveal that higher conversions of N₂O can be achieved by the catalysts synthesized from the microemulsion process at lower temperatures (around 400 °C).     

In situ synthesis of vanadium carbide–copper nanocomposite by a modified mechanochemical combustion method

Synthesis of vanadium carbide–copper nanocomposite was achieved via mechanochemical combustion method from reactant mixture of V₂O₅, CuO, C and Mg powders. The obtained samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS). X-ray diffraction investigations indicated that the combustion products were V₄C₃, V₂C and Cu phases. Microstructural studies showed that a nanostructured powder with a mean particle size of about 100 nm was procured in the samples milled for 90 min.     

Poly (l-lactic acid) synthesis using continuous microwave irradiation–simultaneous cooling method

Abstract

In this study, Poly(l-lactic acid) (PLLA) synthesis was studied using direct melt condensation polymerization (DMP) method in an experimental microwave (MW) system where external cooling was applied to keep both temperature (T) and MW power (P) continuous and constant during the polymerization. T, P, reaction time (t), catalyst type, and catalyst amount were considered to determine appropriate process conditions. In addition, some experiments were carried out under the similar process conditions using MW-assisted ring opening polymerization (MW-ROP) and conventional heating (CH) methods. These methods were compared in terms of process performance and various properties of the oligomeric PLLA. According to results, polymerization rate, polymer yield, average-molecular weight, the dispersity, and thermal properties of PLLA products were similar in both MW methods but higher than CH counterparts. Furthermore, low crystallinity of PLLA products synthesized by MW methods showed the effect of MW on the optical purity (L or D) of products. Finally, energy saving was accomplished by 73% and an increase of polymer production rate by 37.7% in MW-DMP method.     

Synthesis of silica aerogel microspheres by a two-step acid–base sol–gel reaction with emulsification technique

Journal of Porous Materials - Silica aerogel microspheres were synthesized by a two-step acid–base sol–gel reaction in water-in-oil emulsion systems, in which tetraethoxysilane was used...     

Tautomerism of a compartmental Schiff base ligand and characterization of a new heterometallic CuII–DyIII complex — Synthesis,structure and magnetic properties

A crystal structure of a compartmental ligand N,N′-bis(2,3-dihydroxybenzylidene)-1,3-diaminopropane (H₄L = C₁₇H₁₈N₂O₄) (1) containing N₂O₂-inner and O₄-outer coordination sites and a characterization of its novel diphenoxo-bridged discrete dinuclear complex [CuDy(H₂L)(MeOH)(NO₃)₃]·2MeOH (2) are reported. The Schiff base ligand 1 crystallizes in the orthorhombic P2₁2₁2₁ space group with a molecule in a bent conformation. The compound at 100 and 293 K displays the keto-enol tautomerism with the equilibrium in both temperatures shifted with a different degree towards the zwitterionic keto-amino form. The quantum chemical calculations showed preferences for enol-imino form in a gas phase and for keto-amine in solutions. The keto-amino tautomer is stabilized by intermolecular interactions. The complex 2 crystallizes in the triclinic P-1 space group as a dinuclear compound with Cu^IIDy^III core. The Dy(III) ion is nine-coordinated whereas the coordination number of Cu(II) is five. The temperature dependence of the magnetic susceptibility and the field-dependent magnetization indicated that the interaction between Cu(II) and Dy(III) metal centers in 2 is ferromagnetic.     

Extraction kinetics of Fe(III) by di-(2-ethylhexyl) phosphoric acid using a Y–Y shaped microfluidic device

The extraction kinetics of Fe^III by di-(2-ethylhexyl) phosphoric acid (D2EHPA) were investigated using a Y–Y shaped microfluidic device. Finite-volume simulations were used to examine the accuracy of a single-step dimeric reaction mechanism in fitting the experimental data. Results demonstrate the validity of the proposed mechanism and show that Fe^III extraction occurred at a slow rate (second-order forward rate constant of k₁ = (3.0 ± 0.1) × 10⁻⁶ m⁴/mol s) under a mixed reaction–diffusion resistance regime. The present study provides insight for the control of Fe^III extraction rates in hydrometallurgical processes.     

Effect of tartrate on the morphological characteristics of the copper–tin electrodeposits from a noncyanide acid bath

Copper and tin were electrodeposited on platinum substrates from a 1.0 M sulphuric acid plating bath in the presence and absence of tartrate. Voltammetric curves indicated two deposition processes, at –0.310 and –0.640 V, which do not shift upon addition of tartrate to the plating bath. The presence of tartrate decreased the current density in the region of the more cathodic process. The metals were electrodeposited at both deposition potentials and the deposits have the same proportions of copper and tin either with or without tartrate in the plating bath, as observed by AAS. X-ray spectra suggested that a mixture of Cu and -Cu₆Sn₅ alloy was deposited at the less cathodic potential. SEM analysis showed that tartrate affects the morphology of the films.     

Cleavage of the C–N bond of a peptide group by a copper(II)-peroxide adduct with an η1-coordination mode

We have obtained clear evidence that a copper(II)-peroxide adduct with an η¹-coordination mode can cleave the C–N bond of a peptide group and hydroxylate the alkyl group nearby; this may provide helpful information for elucidation of the reaction mechanism of PAM, peptidylglycine α-amidating monooxygenase.     

Modifying polysulfone into a bidentate Schiff base type macromolecular ligand and study on photoluminescence property of polymer–rare earth complexes of Eu(III) and Tb(III)

Chloromethylated polysulfone (CMPSF) was directly transformed into aldehyde (AL) group-functionalized polymer via Kornblum reaction, and then polysulfone was modified to a bidentate Schiff base (BS) type macromolecular ligand, PSF-ASB, via Schiff base reaction with 3-aminopyridine as reagent. Afterward, luminescent binary and ternary polymer-rare earth complexes, PSF-(ASB)₃-Eu (III) and PSF-(ASB)₃-Eu(III)-(Phen)₁ (o-phenanthroline, Phen), were prepared. The macromolecular ligand PSF-ASB and the complexes were fully characterized by FTIR, ¹H-NMR, UV spectroscopy and TGA. The photoluminescence properties and mechanisms of the complexes were investigated in depth. The experimental results show that the macromolecular ligand PSF-ASB itself emits strong fluorescence. However, after coordinating to Eu(III) ion, its fluorescence intensity weakens remarkably, implying that there occurs an intramolecular energy transfer. The complexes of Eu(III) ion exhibit stronger characteristic fluorescence emission of Eu(III) ion, whereas the complex of Tb(III) ion has no photoluminescence property, indicating that the bonded ligand ASB can effectively sensitize the fluorescence emission of Eu(III) ion and suggesting that the triplet state energy of the bonded ligand ASB is well matched with the resonant state level of Eu(III) ion. More importantly, relative to general polymer-rare earth complexes, for these luminescent polymer-rare earth complexes prepared in this study, the backbone of the macromolecular ligand PSF-ASB also takes part in the sensitization towards Eu(III) ion because of that half of aryl rings of a greater π bond conjugate system of ASB comes from PSF skeleton, displaying a great difference with other luminescent polymer-rare earth complexes.     

Removal of nickel(II) from aqueous solutions using iminodiacetic acid functionalized polyglycidyl methacrylate grafted-carbon fibers☆

Iminodiacetic acid functionalized polyglycidyl methacrylate grafted-carbon fibers (PGMA-IDA/CFs) were prepared for Ni(II) removal from aqueous solutions. The effects of solution pH value, temperature and adsorption time were investigated. The maximum adsorption capacity of Ni(II) on PGMA-IDA/CFs is 0.923 mmol·L?1 · g?1 at pH 5.2 and 50 °C. Kinetic data indicate that the adsorption process matches the pseudo-second-order model and Elovich kinetic model. Thermodynamic data suggest that the adsorption process is endothermic spontaneous reaction.     

Optimization of Cu(II)-ion imprinted nanoparticles for trace monitoring of copper in water and fish samples using a Box–Behnken design

We describe a nanoparticles ion-imprinted polymer (IIP) for the selective preconcentration of copper (II) ions. It was obtained by precipitation polymerization from 2-vinylpyridine (the functional monomer), ethylene glycol dimethacrylate (the cross-linker), 2,2′-azobisisobutyronitrile (the initiator), 2,9-dimethyl-1,10-phenanthroline (the copper-binding ligand) and nickel nitrate (the template ion) in acetonitrile solution. The IIP particles were characterized by Fourier Transformed Infra Red Spectroscopy (FTIR), thermogravimetric and differential thermal analysis, and by scanning electron microscopy. The optimization process was carried out using the Box–Behnken design (BBD). Effects of several factors such as solution pH for adsorption, amount of polymer, type, concentration and volume of eluent for extraction, as well as adsorption and desorption times were investigated. Under the optimum conditions (type and concentration of eluent, HCl 1.6 mol L^?1; volume of eluent, 6 mL; adsorption solution pH, 6.0; amount of polymer, 30 mg; adsorption time, 25 min; desorption time, 25 min), preconcentration factor of the proposed method was approximately 100. Under the optimized conditions, the detection limit was found to be 0.1 μg L^?1, while the relative standard deviation (RSD) for six replicate measurements was calculated to be <4%.     

The dimeric and two-dimensional copper(II) complexes constructed from salicylic acid and 4,4′-bipyridine

Two novel complexes, [Cu₂(Hsal)₄(4,4^′-bipyridine)(H₂O)₂(DMF)₂] (1) (H₂sal=salicylic acid) and {[Cu(Hsal)₂(4,4^′-bipyridine)](H₂O)(H₂sal)}_n (2), were synthesized by layered-solution method and structurally characterized. Geometries of copper atoms in both complexes exhibit square pyramidal. Complex 1 is a dimer and hydrogen bonds between water and DMF molecules extend the structure into 1D hydrogen bonding network. Complex 2 consists of two-dimensional square framework structure.     

New dinuclear cobalt (ΙΙ, ΙΙΙ) and tetranuclear manganese (ΙΙΙ) complexes assembled by a polydentate Schiff-base ligand: synthesis,structure and magnetic properties

The reactions of 2-(((2-hydroxy-3-methoxyphenyl)methylene)amino)-2-(hydroxymethyl)-1,3-propanediol (H₄L) and Mn(ClO₄)₂·6H₂O or Co(SCN)₂·3H₂O in the presence of triethylamine in methanol led to the formation of two new complexes [Mn^ΙΙΙ₄(HL)₂(H₂L)₂(CH₃OH)₄]·4CH₃OH·(ClO₄)₂ (1) and [Co^ΙΙCo^ΙΙΙ(H₂L)₂(CH₃OH)(SCN)]·1.5CH₃OH·1.5H₂O (2), respectively. According to structural data and magnetic properties tetranuclear complex 1 contains four homo-valence manganese (ΙΙΙ) atoms, while in the binuclear complex 2 composed of hetero-valence bi- and trivalent cobalt (ΙΙ, ΙΙΙ) atoms. Weak antiferromagnetic exchange interactions between neighboring manganese ions in 1 have place. χ_MT for 2 was fitted using a model of isolated cobalt (ΙΙ) ion with zero-field splitting parameters and the study confirms its mixed valence Co^ΙΙ/Co^ΙΙΙ nature. No slow magnetic relaxation effects were observed for both complexes in the absence of an applied dc magnetic field.     

Synthesis of AlN powder from Al(OH)3 by reduction–nitridation in a mixture of NH3–C3H8 gas

Aluminum nitride (AlN) powders were synthesized by gas-reduction–nitridation of aluminum hydroxide (Al(OH)₃) powders using a mixture of NH₃ and C₃H₈ gases. A high conversion to AlN (over 70% of naitridation ratio) and single-phase AlN were achieved over 1200 °C. The specific surface area of the products decreased with increasing of reaction temperature and soaking time, and products obtained contain much lesser oxygen than those of the previous researches. The reason why such nanosized AlN powders were easily obtained from Al(OH)₃ was considered to be the higher surface areas of transition alumina formed by dehydration of Al(OH)₃ during firing.     

Solvent-induced generation of two cadmium-based metal–organic frameworks from 1, 3, 5-benzenetricarboxylic acid ligand

Two cadmium-based metal–organic frameworks (MOFs), namely [Cd₅(BTC)₄(DMAc)₂(H₂O)₂DMF]·2[H₂N(CH₃)₂]·4DMAc (JUC-133) and [Cd₃(BTC)₂(DMSO)₄] (JUC-134) (JUC = Jilin University, China), based on 1, 3, 5-benzenetricarboxylic acid ligand (H₃BTC) were synthesized by solvent-induced strategy under solvothermal conditions and characterized by single crystal X-ray diffraction, elemental analysis, FT-IR spectroscopy, luminescent spectroscopy, TGA analysis, and powder X-ray diffraction. The ligand is connected to cadmium metals to form different cores with distinctive coordination modes to generate different structures. JUC-133 displays a new three-dimensional (3D) topology with the point symbol (4·6²)₄(4·8²)₄(4²·6⁵·8³)₄(8⁶) based on Cd₂(COO)₅ and Cd₂(COO)₄ as secondary building units (SBUs), which is unknown in previously reported MOFs. JUC-134 can be symbolized as a rutile (rtl) topology with the point symbol (4·6²)₂(4²·6¹⁰·8³) based on Cd₃(COO)₆ as SBUs. Furthermore, the luminescent of the ligand H₃BTC and compounds were measured at room temperature. It is worth noting that the solvent could play an important role in the structural assembly process.