Synthesis,molecular and electronic structures of half-sandwich ruthenium(II) complexes with pyrimidine-based ligands

The complexes [(C₆H₆)RuCl₂(Hmtp)] and [(C₆H₆)RuCl₂(C₄H₄N₂)] have been prepared and studied by IR, ¹H NMR, UV–VIS spectroscopy and X-ray crystallography. The complexes were prepared by reactions of [(C₆H₆)RuCl₂]₂ with 7-hydroxy-5-methyl[1,2,4]triazolo[1,5-a]pyrimidine (Hmtp) and pyrimidine, respectively, in methanol. The electronic structures and UV–Vis spectra of the complexes have been calculated using the TD–DFT method.     

Synthesis, characterization, and molecular structure of Ru(II) complex containing 2,5-pyridinedicarboxylic acid

This article presents a combined experimental and computational study of Ru(II) complex containing 2,5-pyridinedicarboxylic acid ligand. The novel complex [Ru(py-2,5-COOH)₂(PPh₃)₂]·3H₂O has been obtained in the reaction of [RuCl₂(PPh₃)₃] with 2,5-pyridinedicarboxylic acid in methanol and has been studied by IR, ¹H, ³¹P NMR, UV–Vis spectroscopy, and X-ray crystallography. The electronic structure of [Ru(py-2,5-COOH)₂(PPh₃)₂] has been calculated with the density functional theory (DFT) method. The spin-allowed electronic transitions of the complex have been calculated with the time-dependent DFT method, and the UV–Vis spectrum has been discussed on this basis and rationalized by determination of ligand field splitting (10Dq) and Racah’s parameters from the experimental spectrum. The luminescence property of the complex has been examined.     

The reaction between [RuCl<Subscript>2</Subscript>(PPh<Subscript>3</Subscript>)<Subscript>3</Subscript>] and hydroxyquinoline carboxylic acid

The reactions of [RuCl₂(PPh₃)₃] with 8-hydroxy-2-methyl-quinoline-7-carboxylic acid was examined, and a novel ruthenium(II) complex—[Ru(PPh₃)₂(C₅H₈NO)₂]—was obtained. The compound was studied by IR, UV–vis spectroscopy, and X-ray crystallography. The molecular orbital diagram of the complex was calculated with the density functional theory (DFT) method. The spin-allowed singlet–singlet electronic transitions of the compound were calculated using the time-dependent DFT method, and the UV–vis spectrum of the compound was discussed, on this basis. The luminescence property of the [Ru(PPh₃)₂(C₅H₈NO)₂]was examined.     

Ruthenium complexes of 4,4′-bi-1,2,3-thiadiazole and azoimine ligands: syntheses,crystallography, and electrochemical studies

Abstract  

Five ruthenium complexes of the general type trans-[Ru^II(btd)(Azo)Cl₂] ({Azo = PhN=NC(COMe) = NC₆HY, where Y = H (a), Me (b), OMe (c), Cl (d) or Br (e)} and btd = 4,4′-bi-1,2,3-thiadiazole) have been prepared by the reaction of RuCl₃ with the ligands in the presence of LiCl. These complexes have been characterized by spectroscopic (IR, UV–Vis, and NMR) and electrochemical techniques. In addition, the complex trans-[Ru^II(btd)(L5)Cl₂] (complex 5) has been characterized by X-ray diffraction analysis. The electrochemical parameter for the π-excessive ligand (btd) is reported. The absorption spectrum of complex 5 in acetonitrile has been modeled by time-dependent density functional theory.     

The reactions of 2-benzoylpyridine with [RuHCl(CO)(PPh3)3] and [(C6H6)RuCl2]2

The reactions of [RuHCl(CO)(PPh₃)₃] and [(C₆H₆)RuCl₂]₂ with 2-benzoylpyridine have been examined, and two novel ruthenium(II) complexes – [RuCl(CO)(PPh₃)₂(C₅H₄NCOO)] and [RuCl₂(C₁₂H₉NO)₂] – have been obtained. The compounds have been studied by IR and UV–Vis spectroscopy, and X-ray crystallography. The molecular orbital diagrams of the complexes have been calculated with the density functional theory (DFT) method. The spin-allowed singlet–singlet electronic transitions of the compounds have been calculated with the time-dependent DFT method, and the UV–Vis spectra of the compounds have been discussed on this basis.     

Synthesis, physical–chemical, and catalytic properties of mixed compositions Ag/H3PMo12O40/SiO2

Deposited catalysts composition H₃PMo₁₂O₄₀/SiO₂ and Ag/H₃PMo₁₂O₄₀/SiO₂ have been synthesized on the basis of fumed silica, including milling technique. Physical–chemical characteristics of prepared catalysts have been studied by means of XRD, DTA-TG, FTIR, UV–Vis spectroscopy, and adsorption of nitrogen. Catalysts possess meso- or meso-macroporous structure and contain deposited Keggin heteropolycompounds. Deposition of heteropolycompounds on support with high specific surface area results in increase of selectivity to epoxide in epoxidation reactions. The use of milling during catalyst synthesis leads to further growth of selectivity of epoxides formation.     

Photocatalytic degradation of Orange II by titania addition to sol–gel glasses

Glasses on SiO₂–CaO–ZnO–B₂O₃–K₂O–Al₂O₃ oxide system modified by addition of titania (0, 3, 5, 12, and 20% w) have been prepared by sol–gel method. The obtained gels were aged, dried and fired at 600 °C/1 h in order to stabilise the glass. The resulting fired powders were characterised by UV–Vis–NIR spectroscopy, scanning electron microscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD). Their photocatalytic capacity on the degradation of Orange II dye has been studied. The XRD and TEM studies indicate that system becomes amorphous with a nanostructured microstructure. From UV–Vis–NIR results the band gap calculated is around 3.5 eV for all modified glasses. Photoactivity of powders depends on amount of titania in glass composition and the specific surface area of prepared samples. The sample with highest surface area and lowest addition of titania (3% w sample) shows similar activity than commercial anatase used as reference.     

Synthesis and non-isothermal degradations of the bridged diacetato–diamido–diamine–uranyl complex

The new bridged diacetato–diamido–diamine–uranyl complex {2[(UO₂)(H₂N)(H₃N)(OOCCH₃)]} was prepared and characterized by elemental analysis, IR measurement as well as TG and DTA analysis. The kinetic parameters; activation energy (E_a), pre-exponential factor (A) and the order of decomposition (n) were calculated from TG curves using Coats–Redfern and Flynn–Wall–Ozawa methods. The mechanism of decomposition has been established from TG and DTA data. The data obtained agree quite well with the expected structure and show that the complex finally decomposes to form UO₃. A general mechanism describing the formation of bridged complex {2[(UO₂)(H₂N)(H₃N)(OOCCH₃)]} is proposed.     

Hydrothermal synthesis of (Fe,N) co-doped TiO<Subscript>2</Subscript> powders and their photocatalytic properties under visible light irradiation

(Fe, N) co-doped titanium dioxide powders have been prepared by a quick, low-temperature hydrothermal method using TiOSO₄, CO(NH₂)₂, Fe(NO₃)₃, and CN₃H₅ · HCl as starting materials. The synthesized powders were characterized by XRD, TEM, BET, XPS, and UV–Vis spectroscopy. Experimental results show that the as-synthesized TiO₂ powders are present as the anatase phase and that the N and Fe ions have been doped into the TiO₂ lattice. The specific surface area of the powders is 167.8 m²/g by the BET method and the mean grain size is about 11 nm, calculated by Scherrer’s formula. UV–Vis absorption spectra show that the edge of the photon absorption has been red-shifted up to 605 nm. The doped titanium dioxide powders had excellent photocatalytic activity during the process of photo-degradation of formaldehyde and some TVOC gases under visible light irradiation.     

Polymeric and monomeric dipicolinate complexes with 4-hydroxymethyl pyridine: spectral, structural, thermal and electrochemical characterization

Polymeric copper(II), [Cu(μ-dpc)(μ-4-hymp)] _n (1), and monomeric nickel(II), [Ni(dpc)(4-hymp)(H₂O)₂]·H₂O (2), (dpc: dipicolinate, 4-hymp: 4-hydroxymethyl pyridine), dipicolinate complexes have been prepared and characterized by spectroscopic (IR, UV–Vis, EPR), thermal (TG/DTA), X-ray diffraction technique and electrochemical methods. In both the dipicolinate complexes, the dpc dianion acts as a tridentate ligand. In polymeric copper(II) complex, the 4-hymp and dpc ligands adopt a bridging position between the Cu(II) centers, forming the elongated octahedral geometry. The polymeric chains are linked to one another via O–H···O hydrogen bond interactions, forming the 3-D polymeric structure. The Ni(II) ion is bonded to dpc ligand through pyridine N atom together with one O atom of each carboxylate group, two aqua ligands and N pyridine atom of 4-hymp, forming the distorted octahedral geometry. The Ni(II) complexes are connected to one another via O–H···O hydrogen bonds, forming R ₄²(18) motifs in 2-D pattern. The powder EPR spectra of copper(II) complex have indicated that the paramagnetic center is in rhombic symmetry with the Cu²⁺ ion having distorted octahedral geometry. IR and UV–Vis spectroscopes all agree with the observed crystal structure.     

Synthesis, molecular, crystal and electronic structure of [(C6H6)RuCl(1,10-C12H8N2)]Cl

The [(C₆H₆)RuCl(1,10-C₁₂H₈N₂)]Cl complex has been prepared and studied by IR, UV-Vis, ¹H NMR spectroscopy and X-ray crystallography. The complex was prepared in reaction of [(C₆H₆)RuCl₂]₂ with 1,10-phenatroline in acetone. The electronic spectrum of the compound has been calculated using the TDDFT method.     

Synthesis,crystal structure,and properties of a three-dimensional coordination polymer [Cd(PMP)2] n

A new Cd(II) coordination polymer, [Cd(PMP)₂] _n (1) [PMP = 1-phenyl-3-methyl-5-pyrazolone], has been synthesized by the reaction of Cd(CH₃COO)₂·2H₂O with PMP and characterized by elemental analysis, IR spectrum, fluorescence spectrum, UV–vis spectrum, TG–DTA, and electrochemical analysis. Single crystal X-ray diffraction reveals that the complex has a three-dimensional network. Each PMP acts as bidentate bridging ligand and each Cd(II) center is surrounded by two O atoms and two N atoms from four different PMP ligands to form distorted tetrahedral coordination geometry. The photoluminescence study shows the complex exhibited strong solid state blue fluorescent emission at room temperature, and the TG–DTA analysis demonstrated that it has highly thermal stability. Furthermore, the electrochemical property of the complex has been investigated for the first time in DMF by cyclic voltammetry, and the results showed that it has an irreversible process.     

The mononuclear ruthenium(III)-2,3,5,6-tetrakis(2-pyridyl)pyrazine complex [Ru(bpy)(tppz)Cl][PF<Subscript>6</Subscript>]<Subscript>2</Subscript>: synthesis,crystal structure,electrochemical, and spectroelectrochemical studies

The mononuclear Ru(III) complex, [Ru(bpy)(tppz)Cl][PF₆]₂.acetylacetone, where tppz is 2,3,5,6-tetrakis(2-pyridyl)pyrazine and bpy is 2,2′-bipyridine, has been prepared and characterized by physicochemical and spectroscopic methods, cyclic voltammetry, and single crystal X-ray structure analysis. The coordination around the Ru(III) center is distorted octahedral, with bite angles of 80.70–161.83° for the chelating bpy and tppz ligands. The two pyridyl rings of the bpy ligand are nearly coplanar. UV–vis spectroelectrochemical studies of this complex in acetonitrile showed a reversible redox behavior evaluated by the maintenance of isosbestic points in the UV–vis spectrum for both forward reduction and reverse oxidation processes. Magnetic susceptibility data derived from paramagnetic NMR data revealed an effective magnetic moment of 1.79 BM at room temperature.     

Synthesis and characterisation of [RuCl2(PPh3)2(C16H11NO)] complex

The reaction of [RuCl₂(PPh₃)₃] complex with 1-isoquinolyl phenyl ketone has been examined. A new ruthenium(II) complexes–[RuCl₂(PPh₃)₂(C₁₆H₁₁NO)] has been obtained and characterised by IR and UV-VIS measurements. Crystal structure of the complex has been determined. The electronic spectrum of the complex has been calculated by TDDFT method.     

Silver nanoparticle-initiated chemiluminescence reaction of luminol-AgNO3 and its analytical application

Ag⁺ has been regarded as an inert chemiluminescent oxidant. In this work, it was found that in the presence of silver nanoparticles (AgNPs), AgNO₃ could react with luminol to produce strong chemiluminescence (CL). The AgNPs with smaller size could initiate stronger CL emission. To investigate the CL mechanism of the AgNPs–luminol–AgNO₃ system, the UV–visible spectra and the CL spectrum of the CL system were obtained. The CL reaction mechanism involving catalysis was proposed. Compared with the reported nanoparticles–luminol–H₂O₂ CL system, the AgNPs–luminol–AgNO₃ CL system has the advantages of low background and good stability. Moreover, the new CL system was used in immunoassay for IgG.     

Binuclear vanadium(V) complexes of bis(aryl)adipohydrazone: synthesis,spectroscopic studies,crystal structure and catalytic activity

Three new binuclear vanadium(V) complexes of bis(aryl)adipohydrazones (H₄L¹ = bis((2-hydroxynaphthalen-1-yl)methylene)adipohydrazide, H₄L² = bis(5-bromo-2-hydroxybenzylidene)adipohydrazide, and H₄L³ = bis(2-hydroxy-3-methoxybenzylidene)adipohydrazide) were synthesized by direct reaction of [VO(acac)₂] with the hydrazone ligands. The ligands and complexes were characterized by FT–IR, UV–Vis, and NMR spectroscopic methods. The crystal structures of the complexes of L¹ and L³ were determined by X-ray analyses. The solid-state structure of the complex of L¹ features a 1D hydrogen-bonded chain from N⋯H–O hydrogen bonding. The catalytic activities of these complexes have been tested in the oxidation of various hydrocarbons using H₂O₂ as the terminal oxidant. Generally, good to excellent conversions have been obtained.     

Selective peracetic acid determination in the presence of hydrogen peroxide using a label free enzymatic method based on catalase

Peracetic acid (PAA) is selectively determined in the presence of hydrogen peroxide (H₂O₂) by using the self-indicating UV–Vis molecular absorption properties of catalase. The PAA reacts with the protein giving an intermediate (Cat-I) which is reduced back by the aminoacid core surrounding the hemegroup. Since the original form of the enzyme and the Cat-I have different UV–Vis absorption properties, the absorbance changes can be used for PAA determination. The H₂O₂/catalase reaction is extremely fast so that neither Cat-I compound nor kinetic interferences are observed. The method permits PAA determination in the 5 × 10⁻⁷ to 1.5 × 10⁻⁵ M range, the reproducibility being between 1% and 10%. Using this method, PAA has been successfully determined in water samples treated with commercial PAA/H₂O₂ biocides. A theoretical study has also been carried out for obtaining a mathematical model able to analytically describe the process.     

A Novel Uranyl Complex with Dimeric Lacunary Polyoxoanion: [(A-α-SiW<Subscript>9</Subscript>O<Subscript>33</Subscript>)<Subscript>2</Subscript>K{UO<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)}<Subscript>2</Subscript>]<Superscript>11−</Superscript>

A novel uranyl complex with dimeric lacunary polyoxoanion like open-mouthed clam, Na₅[(A-α-SiW₉O₃₃H₃)₂K{UO₂(H₂O)}₂], was prepared and characterized by elemental analysis, infrared and ultraviolet–visible spectroscopy and single crystal X-ray diffraction. In the anion, two A-α-SiW₉O₃₄¹⁰⁻ groups share two terminal oxygen atoms O_d′ derived from removal of three corner-shared W atoms from saturated α-Keggin anion, forming a dimeric anion with an open mouth in which potassium ion and uranyl ions are coordinated. Uranium atom adopts a pentagonal bipyramidal geometry. The coordinating anions are linked by sodium ions via coordination of terminal or bridging oxygen atoms, forming two-dimensional layer arrangement. Between the layers are the hydrogen bonds from which a supramolecular architecture is created. UV–VIS spectrum gives W–O and U–O charge transfer transitions at 230–265 and 432 nm, showing the change of geometry of the polyanion and weakening of the U–O bonds of the uranyl cation. Electronic supplementary material The online version of this article () contains supplementary material, which is available to authorized users.     

Synthesis,molecular, crystal and electronic structure of [(C6H6)Ru(1,2,4-triazole)3](CF3SO3)2

[(C₆H₆)Ru(1,2,4-triazole)₃](CF₃SO₃)₂ has been prepared and studied by IR, electronic and ¹H?NMR spectroscopy and X-ray crystallography. The complex was prepared by reaction of [(C₆H₆)RuCl₂]₂ with 1,2,4-triazole in the presence of AgCF₃SO₃ in methanol. The electronic spectrum of the compound has been calculated using the TDDFT method.     

Ni2+ cation and imidazole as corrosion inhibitors for carbon steel in sulfuric acid solutions

Abstract  

The effect of Ni²⁺ cation, imidazole, and mixtures of them on the corrosion behavior of carbon steel in 0.5 M H₂SO₄ solution was studied by using galvanostatic polarization, potentiodynamic anodic polarization, and weight-loss techniques. Ni²⁺ cation, imidazole, and mixtures of them provide a good protection to carbon steel against pitting corrosion in chloride-containing solutions. The inhibiting solutions were analyzed by using UV–Vis spectrophotometry. The inhibition was explained on the basis of formation of a complex between the two components. The inhibition mechanism was discussed in terms of the results derived from corrosion and UV–Vis spectrophotometric measurements as well as conductometric investigations.