Synthesis and characterization of N-heterocyclic carbene–PdCl2–1H-benzotriazole complexes and their catalytic activities toward Mizoroki–Heck and Sonogashira reactions

Four heteroleptic palladium complexes containing both N-heterocyclic carbenes and 1H-benzotriazole were synthesized and characterized. The solid-state structures show mononuclear carbene palladium complexes with each palladium coordinated by an NHC, the 3-position nitrogen of 1H-benzotriazole and two trans chlorides. The catalytic performance of the complexes for Mizoroki–Heck and Sonogashira reactions were further investigated. The results reveal that the complexes show high catalytic activities for coupling of aryl bromides with alkenes and alkynes.     

Synthesis and structure of mono- and dinuclear cyclopentadienyl–indenyl complexes of iron(II) and further reactions to mixed tri- and tetranuclear iron–cobalt complexes

The reaction of a mixture of sodium cyclopentadienide and the monolithium salt or dilithium salt of 2,2-bis(indenyl)propane with FeCl₂ leads to the mononuclear complex [(η⁵-C₅H₅)Fe(η⁵-ind-C(CH₃)₂-ind)] (ind = 1-indenyl) (1) and the dinuclear complex [{(η⁵-C₅H₅)Fe(η⁵-ind)}₂C(CH₃)₂] (2), respectively. [(η⁵-Me₅C₅)Fe(tmeda)Cl] reacts with dilithium 1,1′-biindenyl under formation of [{(η⁵-Me₅C₅)Fe}₂(μ-η⁵:η⁵-1,1′-biind)] (4). Due to the annelated arene rings of the η⁵-indenyl ligands, 2 and 4 may act as 4-electron donor ligands, as exemplified by the reaction with the triple-decker complex [{(η⁵-Me₅C₅)Co}₂(μ-η⁶:η⁶-toluene)], which afforded the tetranuclear dimer of triple-decker complexes [{(η⁵-C₅H₅)Fe(η⁵-Me₅C₅)Co(μ-η⁵:η⁴-1-ind)}₂C(CH₃)₂] (3) and the trinuclear complex [{(η⁵-Me₅C₅)Fe}₂(η⁵-Me₅C₅)Co(μ₃-η⁵:η⁴:η⁵-1,1′-biind)] · Et₂O (5 · Et₂O) by replacement of the central toluene deck, respectively. The [(η⁵-Me₅C₅)Co] fragments of 3 and 5 are bonded via the six-membered rings of the indenyl ligands in a η⁴-fashion. Caused by the coordination to the Co atoms the six-membered rings lose their planarity and adopt a butterfly structure. The coordination geometry of the Fe atoms is similar in all five complexes. Each Fe atom is coordinated by the C atoms of one of the five-membered rings of the indenyl ligands in a slightly distorted η⁵ manner (η³ + η²-coordination) and by a cyclopentadienyl ligand in a regular η⁵-fashion. The structures of 3 and 5 represent the first examples of slipped triple-decker complexes which comprise indenyl ligands in a μ-η⁵:η⁴ coordination mode.     

Synthesis and structural characterization of iron–sulfur complexes with hydrophilic nitrogen–phosphorus ligands

Reaction of the parent complex (μ-PDT)Fe₂-(CO)₆ (A) (PDT = 1,3-SCH₂CH₂CH₂S^2?) with the bidentate N/P ligand [(Ph₂P)₂N(C₆H₄Cl-p)] in the presence of Me₃NO as decarbonylating agent produced an unexpected iron–sulfur complex [(μ-PDT)Fe₂(CO)₅{PPh₂(NHC₆H₄Cl-1,4)}] (1). Extending this chemistry further, two similar complexes [(μ-PDT)Fe₂(CO)₅{PPh₂(NHC₆H₄NO₂-1,4)}] (2) and [(μ-PDT)Fe₂(CO)₅{PPh₂(NHC₆H₄CO₂Et-1,4)}] (3) could be prepared from the simple substitution reactions of the precursor A with the monodentate N/P ligands Ph₂P(NHC₆H₄NO₂-1,4) and Ph₂P(NHC₆H₄CO₂Et-1,4), respectively. These new complexes, which can be considered as active site models of [FeFe] hydrogenases, have been characterized by elemental analysis, FTIR, and NMR (¹H, ¹³C, ³¹P) spectroscopies, as well as by X-ray crystallography for complex 1.     

A comparative study on characterization and photocatalytic activities of gadolinium–boron codoped and mono-doped TiO2 nanoparticles

Gadolinium?Cboron codoped and mono-doped TiO₂ nanoparticles were prepared using a sol?Cgel method, and tested for photocatalytic activity by the UV light after a further calcination process. For comparison, a pure TiO₂ sample was also prepared and tested under the same conditions. The prepared catalysts were characterized by X-ray diffraction, scanning electron microscope, and UV?CVis spectra. The photocatalytic activity of the samples was evaluated through the photo-degradation of three different dyes under UV light. The experiments demonstrated that the gadolinium?Cboron codoped TiO₂ (Gd?CB?CTiO₂) sample calcined at 500?°C possessed the best photocatalytic activity, and the photodegradation rate of the Reactive Brilliant Red K2G aqueous solution could reach to 95.7% under UV irradiation for 80?min. The results showed that Gd?CB?CTiO₂ has smaller crystallite size and higher photocatalytic activity than that of mono-doped TiO₂ samples and undoped TiO₂.     

Electrodeposition and characterization of zinc–nickel–iron alloy from sulfate bath: influence of plating bath temperature

The electrodeposition of ternary zinc–nickel–iron alloy was studied in acidic sulfate bath. The comparison between Zn, Ni, and Fe deposition and Zn–Ni and Zn–Ni–Fe co-deposition revealed that the remarkable inhibition of Ni and Fe deposition takes place due to the presence of Zn²⁺ in the plating bath. The increase in corrosion resistance of ternary deposits is not only attributed to the formation of γ-Ni₂Zn₁₁ phase but also to iron co-deposition and formation of iron phase. It was also found that the bath temperature has a great effect on the surface appearance and the deposit composition. The investigation was carried out using cyclic voltammetry and galvanostatic techniques for electrodeposition, while linear polarization resistance and anodic linear sweeping voltammetry techniques were used for corrosion study. Morphology and chemical composition of the deposits were characterized by means of scanning electron microscopy and atomic absorption spectroscopy.     

Synthesis of fluorine doped tin oxide nanoparticles by sol–gel technique and their characterization

This article presents novel attempt to synthesis of fluorine doped tin oxide (FTO) nanoparticles by sol–gel technique. The synthesized FTO nanoparticles were obtained after calcination. Temperatures of calcination were 600 and 700 °C due to identify changes in the particles size growth. A DG/DTA and FTIR study identifies the oxide and formation of the nanopowders. The XRD studies confirm the tetragonal crystallite structure of fluorine doped tin oxide. The TEM image confirms the size of FTO particles in nanoscale. The electrical studies on FTO nanopowders results the decrease in resistivity profile with increasing calcinations. The optical band gap studies for sol–gel synthesis FTO nanoparticles is found to be in the range of 4.11–3.84 eV conforming decreasing optical band gap with increasing calcinating temperatures.     

FT-IR and thermal studies of iron–nickel–manganese ternary levo-tartrate crystals

Several metallic tartrates deserve special attention due to their various applications. In the present investigation, mixed tartrate crystals of three different metals are reported. Using single diffusion gel growth technique, iron–nickel–manganese (Fe–Ni–Mn) ternary levo-tartrate compound crystals were grown with different concentrations. Spherulitic crystals with different coloration were obtained for various concentrations of metals. The concentrations of metals were determined by EDAX. The presence of functional groups was confirmed using Fourier transform infrared (FT-IR) spectroscopy. The powder XRD study suggested that the crystals belong to the orthorhombic system. The thermal stability of all the samples was studied from room temperature to 900 °C. It was found that the composition of the crystal affects the dehydration and decomposition behaviors. The results are discussed.     

Synthesis and characterization of a series of chiral NHC–Pd complexes derived from l-phenylalanine

The synthesis of a series of chiral Pd(L)PyBr₂ (3a–3e) and Pd(L)PyCl₂ (4d and 4e) complexes from l-phenylalanine is presented (L = (S)-3-allyl-4-benzyl-1-(2,6-diisopropylphenyl)-imidazolin-2-ylidene (a), (S)-4-benzyl-1-(2,6-diisopropylphenyl)-3-(naphthalen-2-ylmethyl)imidazolin-2-ylidene (b), (S)-4-benzyl-3-(biphenyl-4-ylmethyl)-1-(2,6-diisopropylphenyl)imidazolin-2-ylidene (c), (S)-4-benzyl-1-(2,6-diisopropylphenyl)-3-(naphthalen-1-ylmethyl)imidazolin-2-ylidene (d) or (S)-4-benzyl-1-(2,6-diisopropylphenyl)-3-(2,4,6-trimethylbenzyl)imidazolin-2-ylidene (e). The complexes were characterized by physicochemical and spectroscopic methods, and the X-ray crystal structures of 3a–3c and 4d are reported. In each case, there is a slightly distorted square-planar geometry around palladium, which is surrounded by imidazolylidene, two trans halide ligands and a pyridine ligand. There are π–π stacking interactions in the crystal structures of these complexes. Complex 3a showed good catalytic activity in the Cu-free Sonogashira coupling reaction under aerobic conditions.     

Synthesis of 6,8-dichloroquinolones utilizing new method and evaluation of their antibacterial activities

Several 6,8-dichloroquinolone analogues were synthesized from the key intermediate compound of 2,3,4,5-tetrachlorobenzene carbonyl chloride,which was obtained from the starting material of tetrachlorophthalic anhydride.Their in vitro antibacterial activities were evaluated.As a result of this study,compounds 21c and 21d were twofold more potent than ciprofloxacin (CPFX) and norfloxacin (NFLX) against Staphylococcus aureus-9,and with the same potent as CPFX and NFLX while against Escherichia coli-2,but were less potent than references in against Pseudomonas aeruginosa-17.     

Transformation of indium nanoparticles to β-indium sulfide: digestive ripening and visible light-induced photocatalytic properties

We report the transformation of polydispersed dodecanethiol stabilized indium nanoparticles, obtained from bulk indium shot by evaporation/condensation solvated metal atom dispersion (SMAD) technique, into highly monodispersed partially alkyl thiolate-capped β-indiumsulfide (In(2)S(3)) by a postpreparative digestive ripening in high boiling point t-butyltoluene (190 °C) solvent. Upon digestive ripening, the as-prepared polydispersed black indium nanoparticles showed a characteristic color transition from black to cream, pale yellow, yellow, and finally to brown, indicating the transformation of the indium metal nanoparticles into intermediates composed of indium thiolates, sulfides, and polysulfides, and finally into the product In(2)S(3) nanoparticles whose surfaces are partially capped with thiolates. The transformed product (In(2)S(3)) was characterized with UV-vis, XRD, EDX, SEM, XPS, and TEM. From XRD and TEM measurements, the average size of the transformed In(2)S(3) nanoparticles is 5 nm. The optical absorbance of the as-prepared sample showed absorption peaks around 538 and 613 nm; upon digestive ripening these two peaks disappeared and stabilized at 375 nm, providing evidence of strong quantum confinement of excitons. The visible light-induced photocatalytic activity test with the In(2)S(3) nanoparticles showed that 95% of Rhodamine B (RhB) dye degraded after 100 min of irradiation with visible light.     

Synthesis and properties of zinc–nickel–carbon nanotube composite coatings

Composite electrochemical coatings modified with carbon nanotubes were produced on the basis of the zinc–nickel alloy. The functional properties (friction coefficient, protective capacity) of the composite coatings were studied in comparison with zinc–nickel alloys without a dispersed phase. It was found that, upon inclusion of carbon nanotubes particles into zinc–nickel deposits, their sliding friction coefficient decreases by a factor of 1.3–1.4 and the range of passive-state potentials becomes two times wider.     

Synthesis,structure, computational modeling and biological activity of two new Casiopeínas® complexes and their nanoparticles

Abstract

This study was conducted to prepare new complexes and their metal-based nanodrugs in order to reduce the growth of human carcinoma cell lines. For this purpose, an extensive study was performed. First, the mixed-chelate Cu(II) complexes Casiopeínas^® ([Cu(TTA)(phen)(C1O₄)] 1 and [Cu(TTA)(phen)(N₃)Cu(TTA)(phen)H₂O] (C1O₄)·H₂O 2 (TTA = 4,4,4-trifluoro-1-(2-furyl)-1,3-butanedione) were synthesized and characterized by X-ray, FT-IR, UV–Vis spectroscopy, conductivity measurements, diffuse reflection spectroscopy and elemental analysis studies. Complexes 1 and 2 exhibited tetragonal pyramidal geometry. In the following, nanoparticles (NPs) of complexes 3 and 4 with the average size of 81 and 33?nm, respectively, were prepared by an ultrasonic process. Scanning Electron Microscope (SEM) images of samples 3 and 4 showed that the morphologies of the obtained materials are rod and sphere, respectively. Furthermore, the cytotoxic activity of complexes and nanoparticles was investigated against MKN-45 cell lines. The cell proliferation was inhibited for all compounds and nanocompounds in a dose-dependent manner 1?>?2 > 3?>?4 on MKN-45 cells. Finally, docking calculations were performed to describe the mode of binding to DNA of these complexes. Docking simulations suggested that the compounds bind in the minor groove and preferentially bind to A-T base pair regions. Both complexes also interacted with DNA through one hydrogen-bond.     

Synthesis and luminescence-spectral properties of benzoheterocyclic β-diketones and their complexes with europium

In order to solve some environmental and biomedical problems, we synthesized fluorinated heterocyclic β-diketones and estimated the luminescence-spectral properties of these compounds complexes with the ions of rare-earth elements as the possible reagents for immunofluorescence analysis.     

Graphene oxides as support for the synthesis of nickel sulfide–indium oxide nanocomposites for photocatalytic,antibacterial and antioxidant performances

NiS (nickel sulfide)–In₂O₃ (indium oxide) nanostructures and NiS–In₂O₃ decorated on graphene oxide (GO) were demonstrated by ultrasonic/hydrothermal method. The structural study demonstrates the preparation of bixbyite and hexagonal phase of In₂O₃ and NiS for all of the synthesized catalysts. The band gap of the synthesized catalyst was determined to be in the range of 2.30–3.00 eV. A morphological evaluation by field emission scanning electron microscopy of NiS–In₂O₃ decorated on graphene oxide shows support for the NiS–In₂O₃ on the graphene oxide layer. Different test parameters were performed to study the phase and morphology. The particle sizes of the In₂O₃, NiS–In₂O₃ and NiS–In₂O₃/GO nanocomposites were 56.0, 62.0 and 66.0 nm, respectively. The photocatalytic performance of NiS–In₂O₃/GO nanocomposites was examined for the degradation of methylene blue dye under a UV lamp. The prepared sample shows 98.25% photocatalytic degradation within 40 min and at pH 9. With the presence the NiS and GO, the photo-degradation capacities of In₂O₃ and NiS–In₂O₃ are improved owing to the low band gap being calculated in UV–vis DRS analysis. The high ratio of NiS causes the highest photocatalytic properties of NiS–In₂O₃ nanocomposites owing to the enhancement of charge separation efficiency and generation of hydroxyl radicals. This study presents a facile and low-cost method to prepare highly active NiS–In₂O₃/GO nanocomposites. The antibacterial data indicate the significant properties of NiS–In₂O₃/GO nanocomposites for this study.     

Synthesis of mono-, bis-spiro- and dispiro-β-lactams and evaluation of their antimalarial activities

Some new mono-, bis-spiro- and dispiro-β-lactams have been synthesized from imines derived from 9H-fluoren-9-one and a ketene derived from 9H-xanthene-9-carboxylic acid or phenoxyacetic acid by a [2+2] cycloaddition reaction in good to excellent yields varying from 45 to 83%. The biological activity of these monocyclic β-lactams was successfully investigated against Plasmodium falciparum K14 resistant strain with excellent EC₅₀ values up to 5 μM.     

Synthesis and characterization of magnetic nanoparticles

Magnetic nanoparticles with average diameter in the range of 6.4-8.3 nni have been synthesized by a chemical co-precipitation of Fe(Ⅱ)and Fe(Ⅲ)salts in 1.5 M NH4OH solution.The size of the magnetic particles is dependent on both temperature and the ionic strength of the iron ion solutions.The magnetic particles formed at higher temperature or lower ionic strength were slightly larger than those formed at lower temperature or higher ionic strength respectively.In spite of the different reaction conditions,all the resultant nanoparticles are nearly spherical and have a similar crystalline structure.At 300 K,such prepared nanoparticles are superparam-agnetic.The saturation magnetizations for 7.8 and 6.4 nm particles are 71 and 63 emu/g respectively,which are only ~ 20-30% less than the saturation magnetization(90 emu/g)of bulk Fe3O4 Our results indicated that a control of the reaction conditions could be used to tailor the size of magnetic nanoparticles in free precipitation.     

Synthesis of conducting polyaniline—polyanion interpolymer complexes and study of their composition and properties

The polymerization of aniline in the presence of poly(4-styrenesulfonic acid) and poly(2-acryla-mido-2-methyl-1-propanesulfonic acid) results in interpolyelectrolyte complexes with a composition and a dispersion stability depending on the aniline-to-polyanion ratio in the initial reaction mixture. As opposed to polymerization mediated by poly(4-styrenesulfonic acid), the template polymerization of aniline conducted in the presence of poly(2-acrylamido-2-methyl-1-propanesulfonic acid) leads to the structural template effect that manifests itself as the formation of polyaniline containing 1,2- and 1,4-substituted benzene rings. It is found that the electron conductivity of the polyaniline-polyanion interpolyelectrolyte complexes depends not only on the content but also on the nature of the used polyacid and proves to be higher in the case of stoichiometric interpolyelectrolyte complexes formed in the presence of poly(4-styrenesulfonic acid).