Demetallation of methemoglobin in cellulose nanofibril–TiO2 nanoparticle composite membrane electrodes

Porous composite films containing cellulose nanofibrils (from sisal) and TiO₂ nanoparticles (ca. 6 nm diameter) are obtained in a layer-by-layer assembly process. Each layer consists of ca. 0.18 μg cellulose nanofibrils and ca. 0.72 μg TiO₂ (determined by QCMB) and adds a thickness of ca. 16 nm (by AFM) to the uniform deposit. The TiO₂ nanophase is creating conducting pathways for electrons in a relatively open cellulose structure (ca. 82% open pores) potentially suitable for the immobilization of large redox proteins such as methemoglobin.Methemoglobin is shown to readily adsorb into the cellulose–TiO₂ film. However, electrochemical responses for the immobilized methemoglobin in aqueous 0.1 M phosphate buffer at pH 5.5 suggest that facile demetallation occurs. Experiments with Fe³⁺ in the absence of protein result in voltammetric responses indistinguishable from those observed for immobilized methemoglobin. In the presence of ethylenediamine tetraacetic acid (EDTA) the voltammetric signals for the Fe³⁺ immediately disappear. Complementary experiments conducted in 0.1 M acetate buffer at pH 5.5 demonstrate that methemoglobin can indeed be immobilized in electrochemically active form and without demetallation loss of the voltammetric signal in the presence of EDTA. Demetallation appears to occur (i) in the presence of phosphate, (ii) at pH 5.5, (iii) and in the presence of a charged surface.     

Signal enhancement in solution-cathode glow discharge — optical emission spectrometry via low molecular weight organic compounds

HCOOH, CH₃COOH, and CH₃CH₂OH were used as chemical modifiers in a solution-cathode glow discharge. Emission was measured directly from the discharge, without a gas–liquid separator or a secondary excitation source. Emission from Ag, Se, Pb, and Hg was strongly enhanced, and the detection limits (DL) for these elements were improved by up to an order of magnitude using a combination of HCOOH and HNO₃ compared to using HNO₃ alone. The DL was measured for Mg (1 μg/L), Fe (10 μg/L), Ni (6 μg/L), Cu (6 μg/L), Pb (1 μg/L), Ag (0.1 μg/L), Se (300 μg/L), and Hg (2 μg/L). Coefficients of determination (R²) were between 0.9986 and 0.9999. A voltage of 1 kV was used, which produced a current of approximately 70 mA.     

Ion-pairing and reversed phase liquid chromatography for the determination of three different quinolones: Enrofloxacin,lomefloxacin and ofloxacin

Two simple and sensitive high performance liquid chromatographic (HPLC) methods have been developed for the simultaneous determination of three different quinolones: enrofloxacin, lomefloxacin and ofloxacin in their pure and dosage forms, one with reversed phase HPLC and the other with ion-pair HPLC. In reversed phase HPLC, method (A), the mobile phase consists of 2.18% aqueous solution of KH₂PO₄ with pH adjusted to 2.4 ± 0.2 with acetonitrile (80:20; v/v), the mobile phase pumped at flow rate of 1.2 ml min^?1. A Neucleosil C₁₈ column (10 μm, 100 Å), 250 mm length × 4.6 mm diameter was utilized as stationary phase. Detection was affected spectrophotometrically at 294 nm. While in ion-pair HPLC, method (B), the mobile phase was aqueous solution of 0.65% sodium perchlorate and 0.31% ammonium acetate adjusted to pH 2.2 ± 0.2 with orthophosphoric acid: acetonitrile (81:19; v/v), the mobile phase pumped at flow rate of 1.5 ml min^?1. A μ bondapack C₁₈ column (10 μm, 100 Å), 250 mm length × 4.6 mm diameter was utilized as stationary phase. Detection was affected spectrophotometrically at 294 nm. Linearity ranges for enrofloxacin, lomefloxacin and ofloxacin were 4.0–108, 7.0–112 and 8.0–113 μg ml^?1, respectively using method A and 8.0–112, 7.0–112 and 5.0–105 μg ml^?1, respectively applying method B. Minimum detection limits obtained were 0.013, 0.023 and 0.035 μg ml^?1 for enrofloxacin, lomefloxacin and ofloxacin, respectively using method A, and 0.028, 0.023 and 0.011 μg ml^?1 using method B. The proposed methods were further applied to the analysis of enrofloxacin in injection and tablets containing the ofloxacin and lomefloxacin drugs, and the results were satisfied.     

HPLC-PDA analysis of ACE-inhibitors,hydrochlorothiazide and indapamide utilizing design of experiments

A simple, rapid, precise, accurate and sensitive high performance liquid chromatographic method has been developed for simultaneous determination of ACE inhibitors with hydrochlorothiazide and indapamide in pharmaceutical formulations. ‘Design of Experiments’ (DoE) using ‘central composite design’ (CCD) was applied to facilitate method development and optimization. Mobile phase was optimized utilizing response surface methodology using Design Expert software. Chromatographic separation was achieved on Hypersil®-Gold C₁₈ (100 × 4.6 mm, 3 μm, Thermo Fisher Scientific, USA), column at 25 °C. The mobile phase was 58% buffer (5 mM KH₂PO₄, containing triethylamine 0.25 ml/L), 25% acetonitrile and 17% methanol (pH adjusted to 2.8 ± 0.1). The analysis was performed at 215 nm. The mobile phase flow rate was 1.0 ml/min and injection volume 10 μl. The method was validated for linearity, limits of quantitation and detection, accuracy, precision, ruggedness and robustness as per the International Conference on Harmonization (ICH) guidelines. Calibration curves (for lisinopril, hydrochlorothiazide, captopril, imidapril, perindopril, indapamide and trandolapril) were linear in the concentration range of 5–35 μg/ml. The limit of detection and limit of quantitation for experimental drugs ranged from 0.03 to 0.61 and 0.08–1.84 μg/ml respectively.     

Hydrothermal synthesis and thermochemistry of metalloborophosphate of Na2[CuB3P2O11(OH)]·0.67H2O

The pure hydrated metalloborophosphate sample, Na₂[CuB₃P₂O₁₁(OH)]·0.67H₂O, has been synthesized and characterized by XRD, FT-IR, DTA-TG techniques, and chemical analysis. The molar enthalpies of solution of Na₂[CuB₃P₂O₁₁(OH)]·0.67H₂O(s) in 1 mol · dm^?3 HCl (aq), of Cu(OH)₂ (s) in (HCl + H₃BO₃) (aq), and of NaH₂PO₄·2H₂O (s) in (HCl + H₃BO₃ + Cu(OH)₂) (aq) were measured, respectively. With the incorporation of the previously determined enthalpy of solution of H₃BO₃ (s) in 1 mol · dm^?3 HCl (aq), together with the use of the standard molar enthalpies of formation for NaH₂PO₄·2H₂O (s), Cu(OH)₂ (s), H₃BO₃ (s), and H₂O (l), the standard molar enthalpy of formation of ?(4988.4 ± 2.5) kJ · mol^?1 for Na₂[CuB₃P₂O₁₁(OH)]·0.67H₂O at T = 298.15 K was obtained on the basis of the appropriate thermochemical cycle.     

UV-absorption and fluorimetric methods for the determination of alprazolam in pharmaceutical formulation

The development of UV and fluorescence spectrophotometric methods for the quantitative determination of alprazolam in dosage forms using As(III)?SDS system. The two simple and sensitive, spectrophotometric and spectrofluorimetric methods were developed for the determination of alprazolam (ALP) in tablets. These methods are based on formation of ALP?As(III) complex in the presence of SDS. The UV-spectrum of 30% methanolic solution of ALP (5 × 10^?5 M) at pH 6.5 (Mclivaine buffer) was run between 200 and 380 nm. The absorption spectrum of ALP exhibits two peaks with a λ_max. at 255 nm and a weak band at 325 nm. When the spectra of the drug were run at varying pH in the region 200–380 nm, one isosbestic point at 290 nm was observed, which indicated the presence of two ionic conditions in solution. The complex exhibited an absorption maximum at 265 nm and emission peak at 520 nm with respect to the excitation wavelength of 325 nm. The spectrophotometric method was found to be linear in 8.0–17.0 μg ml^?1 range with detection limit of 13.520 μg ml^?1, while 0.05–9.5 μg ml^?1 range was with detection limit of 1.048 × 10^?2 μg ml^?1 by spectrofluorimetric method. The mean percentage recovery of the added quantity was found to be 99.54 (spectrophotometric method) and 100.22 (spectrofluorimetric method) and the %RSD are lower than 0.478 and 0.296 determined spectrophotomerically and spectrofluorimtrically, respectively. This indicates that the proposed method is accurate. The apparent ionization constant of ALP was found to be 9.29. The spectra, experimental conditions were set followed by determination stoichiometry, stability constant and thermodynamic parameters of the As(III), Co(II), Ni(II), and Zn(II) complexes with ALP at pH 6.5. The proposed methods have been successfully applied to the assay of ALP in tablets and the results were statistically evaluated.     

Potentiostatically deposited nanostructured α-Co(OH)2: A high performance electrode material for redox-capacitors

A high specific capacitance was obtained for α-Co(OH)₂ potentiostatically deposited onto a stainless-steel electrode in 0.1 M Co(NO₃)₂ electrolyte at −1.0 V vs. Ag/AgCl. The structure and surface morphology of the obtained α-Co(OH)₂ were studied by using X-ray diffraction analysis and scanning electron microscopy. A network of nanolayered α-Co(OH)₂ sheets was obtained; the average thickness of individual α-Co(OH)₂ sheets was 10 nm, and the thickness of the deposit was several micrometers. The capacitive characteristics of the α-Co(OH)₂ electrodes were investigated by means of cyclic voltammetry and constant current charge–discharge cycling in 1 M KOH electrolyte. A specific capacitance of 860 F g⁻¹ was obtained for a 0.8 mg cm⁻² α-Co(OH)₂ deposit. The specific capacitance did not decrease significantly for the active mass loading range of 0.1–0.8 mg cm⁻² due its layered structure, which allowed easy penetration of electrolyte and effective utilization of electrode material even at a higher mass. This opens up the possibility of using such materials in supercapacitor applications.     

A new intersecting tunnel structure in the AIMIII[PO3(OH)]2 series for AI = Ag,MIII = In: Analysis of structural relationships

A new indium hydroxyphosphate containing silver, AgIn[PO₃(OH)]₂, has been synthesized using hydrothermal method. It crystallizes in the P2₁/c space group with the cell parameters a = 6.6400(2) Å, b = 14.6269(6) Å, c = 6.6616(4) Å, β = 95.681(5)°, V = 643.82(6) Å³, Z = 4. Its three-dimensional framework, built up of corner-sharing PO₃(OH) tetrahedra and InO₆ octahedra, presents intersecting tunnels running along <111> and [100] directions, in which the Ag⁺ cations are located. The presence of hydroxyl groups has been confirmed from IR spectroscopy studies and hydrogen atoms were located from the single crystal X-ray diffraction study. The structural relationships with the other compounds of general formula A^IM^III[PO₃(OH)]₂ are analyzed.     

Amperometric enzyme biosensor for hydrogen peroxide via Ugi multicomponent reaction

A novel strategy based on the Ugi multicomponent reaction was employed for immobilizing horseradish peroxidase on sodium alginate-coated gold electrode. The electrode was employed for constructing an amperometric biosensor device using 1 mM hydroquinone as electrochemical mediator. The electrode showed linear response (poised at −300 mV vs Ag/AgCl) toward H₂O₂ concentration between 70 μM and 8.8 mM at pH 7.0. The biosensor reached 95% of steady-state current in about 12 s and its sensitivity was 33.8 mA/M cm². The electrode retained full initial activity after 30 days of storage at 4 °C in 50 mM sodium phosphate buffer, pH 7.0.     

Vapour pressures,densities, and viscosities of the (water + lithium bromide + potassium acetate) system and (water + lithium bromide + sodium lactate) system

Measurements of thermophysical properties (vapour pressure, density, and viscosity) of the (water + lithium bromide + potassium acetate) system LiBr:CH₃COOK = 2:1 by mass ratio and the (water + lithium bromide + sodium lactate) system LiBr:CH₃CH(OH)COONa = 2:1 by mass ratio were measured. The system, a possible new working fluid for absorption heat pump, consists of absorbent (LiBr + CH₃COOK) or (LiBr + CH₃CH(OH)COONa) and refrigerant H₂O. The vapour pressures were measured in the ranges of temperature and absorbent concentration from T = (293.15 to 333.15) K and from mass fraction 0.20 to 0.50, densities and viscosities were measured from T = (293.15 to 323.15) K and from mass fraction 0.20 to 0.40. The experimental data were correlated with an Antoine-type equation. Densities and viscosities were measured in the same range of temperature and absorbent concentration as that of the vapour pressure. Regression equations for densities and viscosities were obtained with a minimum mean square error criterion.     

Synthesis,structural characterization,and reactivity of the ethyl substituted aluminum hydroxide and catalytic properties of its derivative

The ethyl substituted aluminum hydroxide LAlEt(OH) (2; L = HC[C(Me)N(Ar)]₂; Ar = 2,6-iPr₂C₆H₃) was prepared by the hydrolysis of LAlEt(Cl) (1) in the presence of a N-heterocyclic carbene. The reaction of 2 with Cp₂ZrMe₂ in toluene afforded LAlEt(μ-O)ZrMeCp₂ (3) by evolution of methane, while the reaction of 2 with Cp₃M in THF led to the intermolecular elimination of HCp and formation of LAlEt(μ-O)M(THF)Cp₂ (M = Yb, 4; Er, 5; Dy, 6; Y, 7). Compounds 2 and 3 were characterized by single X-ray structural analysis. Compound 2 crystallizes in the orthorhombic space group P2₁2₁2₁, while compound 3 crystallizes in space group Pnma. In both cases, the displacement of the Al and the γ-C atom out of the NCCN plane is observed in a boat conformation, but with converse direction. Furthermore, compound 3 was used as catalyst for ethylene polymerization.     

Copper(II)–neocuproine reagent for spectrophotometric determination of captopril in pure form and pharmaceutical formulations

A simple, rapid, sensitive and accurate spectrophotometric method for the determination of captopril in pure form and pharmaceutical formulations is developed. The procedure is based on the reaction of copper(II) with captopril in the presence of neocuproine (NC) (2,9-dimethyl-1,10-phenanthroline) reagent in acetate buffer at pH 5.0. Copper(II) is reduced easily by captopril to Cu(I)–neocuproine complex, which shows an absorption maximum at 448 nm. Beer’s law was obeyed in the concentration range 0.3–3.0 μg mL^?1 with a minimum detection limit (LOD) of 0.039 μg mL^?1 and a quantification limit (LOQ) of 0.129 μg mL^?1. For more accurate results, Ringbom optimum concentration ranges was 0.5–2.7 μg mL^?1. The apparent molar absorbtivity and Sandell sensitivity were calculated. The validity of the proposed method was tested by analyzing the pure and pharmaceutical formulations and compared well with those obtained by the official method and demonstrated good accuracy and precision.     

Study of the chemical composition of particulate matter from the Rio de Janeiro metropolitan region,Brazil, by inductively coupled plasma-mass spectrometry and optical emission spectrometry

Air quality in the metropolitan region of Rio de Janeiro was evaluated by analysis of particulate matter (PM) in industrial (Santa Cruz) and rural (Seropédica) areas. Total suspended particles (TSP) and fine particulate matter (PM_2.5) collected in filters over 24 h were quantified and their chemical composition determined. TSP exceeded Brazilian guidelines (80 μg m^− 3) in Santa Cruz, while PM_2.5 levels exceeded the World Health Organization guidelines (10 μg m^− 3) in both locations. Filters were extracted with water and/or HNO₃, and the concentrations of 20 elements, mostly metals, were determined by inductively coupled plasma mass spectrometry (ICP-MS) and optical emission spectrometry (ICP OES). Water soluble inorganic anions were determined by ion chromatography (IC). To estimate the proportion of these elements extracted, a certified reference material (NIST SRM 1648a, Urban Dust) was subjected to the same extraction process. Concordant results were obtained by ICP-MS and ICP OES for most elements. Some elements could not be quantified by both techniques; the most appropriate technique was chosen in each case. The urban dust was also analyzed by the United States Environmental Protection Agency (US EPA) method, which employs a combination of hydrochloric and nitric acids for the extraction, but higher extraction efficiency was obtained when only nitric acid was employed. The US EPA method gave better results only for Sb. In the PM samples, the elements found in the highest average concentrations by ICP were Zn and Al (3–6 μg m^− 3). The anions found in the highest average concentrations were SO₄^2 − in PM_2.5 (2–4 μg m^− 3) and Cl⁻ in TSP (2–6 μg m^− 3). Principal component analysis (PCA) in combination with enrichment factors (EF) indicated industrial sources in PM_2.5. Analysis of TSP suggested both anthropogenic and natural sources. In conclusion, this work contributes data on air quality, as well as a method for the analysis of PM samples by ICP-MS.     

Radiolytic degradation of 4-nitrophenol in aqueous solutions: Pulse and steady state radiolysis study

The radiation induced degradation of 4-nitrophenol (4-NP) has been studied by gamma irradiation, while the reactivity and spectral features of the short lived transients formed by reaction with primary transient radicals at different pHs has been investigated by pulse radiolysis technique. In steady state radiolysis a dose of 4.4 k Gy is able to degrade 98% of 1×10⁻⁴ mol dm⁻³ 4-NP. 4-NP has pK_a at 7.1, above which it is present in the anionic form. At pH 5.2, ^•OH and N₃^• radicals were found to react with 4-NP with rate constants of 4.1×10⁹ dm³ mol⁻¹ s⁻¹ and 2.8×10⁸ dm³ mol⁻¹ s⁻¹, respectively. Differences in the absorption spectra of species formed in the reactions of 4-NP with ^•OH and N₃^• radicals suggested that ^•OH radicals add to the aromatic ring of 4-NP along with electron transfer reaction, whereas N₃^• radicals undergo only electron transfer reaction. At pH 9.2, rate constants for the reaction of ^•OH radicals with 4-NP was found to be higher by a factor of 2 compared to that at pH 5.2. This has been assigned to the deprotonation of 4-NP at pH 9.2.     

Synthesis and investigations of mixed-ligand lanthanide complexes with N,N′-dipyrrolidine-N′′-trichloracetylphosphortriamide,dimethyl-N-trichloracetylamidophosphate, 1,10-phenanthroline and 2,2′-bipyrimidine

Coordination compounds with general formula [Ln(L¹)₃phen], where Ln = Nd, Eu, Er, Yb, HL¹ = N,N′-dipyrrolidine-N′′-trichloracetylphosphortriamide, phen = 1,10-phenanthroline; [Ln(L¹)₃bpm], where Ln = La, Nd, Eu, Gd, Er, Y, bpm = 2,2′-bipyrimidine and [{Ln(L²)₃}₂(μ-bpm)], where Ln = La, Nd, Eu, Gd, Er, Y, HL² = dimethyl-N-trichloracetylamidophosphate have been synthesized and characterized by means of IR and UV–Vis spectroscopy. Crystal structures of [Nd(L¹)₃phen] (1), [Nd(L¹)₃bpm] (2) and [{Nd(L²)₃}₂(μ-bpm)] (3) have been determined. It was found, that in the deprotonated form the phosphoryl ligands (L¹)^? and (L²)^? are coordinated to the neodymium atoms in a bidentate manner via the oxygen atoms of the phosphoryl and the carbonyl groups with formation of six-membered metallocycles. In the case of compounds 1 and 2 the 1,10-phenanthroline (or 2,2′-bipyrimidine) molecules are coordinated to the metals in a bidentate manner via the nitrogen atoms. In contrast 2,2′-bipyrimidine acts in the bidentate-bridge mode forming binuclear complex 3. Variable-temperature magnetic susceptibility measurements of 3 and [{Gd(L²)₃}₂(μ-bpm)] (4) reveal a weak antiferromagnetic interaction between the two magnetic centres, whereas in the case of [{Eu(L²)₃}₂(μ-bpm)] (5) the presence of spin–orbit coupling leads to a deviation from the Curie and Curie–Weiss laws.     

A novel visible spectrophotometric method for the determination of ethamsylate in pharmaceutical preparations and biological samples

A highly sensitive visible spectrophotometric method has been developed to determine ethamsylate in this paper, which is based on using Cu(II) as spectroscopic probe reagent. The study indicates that in the presence of SCN^? and KNO₃, Cu(II) is reduced to Cu(I) by ethamsylate at pH 5.0, and the in situ formed Cu(I) reacts with SCN^? to form into the white emulsion CuSCN that could be stayed upon the surface of water. According to the amount of residual Cu(II), the amount of ethamsylate can be indirectly determined. Under the optimal conditions, Beer's law is applicable in the range of 0.2–9.0 μg/mL (7.60 × 10^?7–3.42 × 10^?5 mol/L) for aqueous standard solution of ethamsylate with linear correlation coefficient of 0.9998. The detection limit and relative standard deviation are 0.12 μg/mL and 1.5%, respectively. And the molar absorption coefficient of the indirect determination of ethamsylate is 1.0 × 10⁵ L/mol cm. The method is successfully applied to determine ethamsylate in pharmaceutical preparations and biological samples.     

New iodate materials as potential laser matrices. Preparation and characterisation of α-M(IO3)3 (M = Y,Dy) and β-M(IO3)3 (M = Y,Ce, Pr,Nd, Eu,Gd, Tb,Dy, Ho,Er). Structural evolution as a function of the Ln3+ cationic radius

Anhydrous yttrium iodate presents polymorphism; two crystalline phases are obtained under hydrothermal conditions. α-Y(IO₃)₃ crystallises in the monoclinic space-group P2₁/c with a three-dimensional structure, whereas β-Y(IO₃)₃ crystallises in the monoclinic space-group P2₁/n with a two-dimensional structure. The lattice parameters are a = 7.038(1) Å, b = 8.466(1) Å, c = 13.317(1) Å, β = 99.65(1)°, V = 782.3(2) Å³, Z = 4 for α-Y(IO₃)₃ and a = 8.685(1) Å, b = 5.964(1) Å, c = 14.958(1) Å, β = 96.99(2)°, V = 769.0(2) Å³, Z = 4 for β-Y(IO₃)₃. The α-form is isostructural with α-Dy(IO₃)₃ studied in this work and α-Ln(IO₃)₃ (Ln = Ce, Pr, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu) already studied. The β-form is isostructural with β-Ln(IO₃)₃ (Ln = Ce, Pr, Nd, Eu, Gd, Tb, Dy, Ho and Er) studied in this work. The structural evolutions as a function of the Ln³⁺ cationic radius are studied. α-Y(IO₃)₃ and β-Y(IO₃)₃ present good thermal stability since they decompose at 600 °C. They are transparent up to 11.5 μm and they have good optical damage thresholds on powder.     

Electrodeposition of polypyrrole–Au nanoparticles composite from one solution containing gold salt and monomer

An easy method of preparation of polymer/metal–nanoparticle composites is reported. KAu(CN)₂ and pyrrole do not react (redox reaction) in solutions of moderate pH. The gold complex, due to its inertness, is stable in the presence of 10 μM CN^? for weeks. Therefore the electrodeposition of controlled amounts of polypyrrole and Au nanoparticles on the graphite surface can be done in one solution by applying a sequence of 0.75 and ? 1.6 V potentials. Pulse deposition of both components leads to substantial improvement of the layer smoothness and homogenous distribution of Au nanocrystallites.     

Synthesis,structure and solid state NMR analysis of a new templated titanium(III/IV) fluorophosphate

The title compound MIL-131 (MIL stands for Material from Institut Lavoisier) was prepared hydrothermally (4 days, 473 K, autogenous pressure) in the presence of an organic base (N((CH₂)₂NH₂)₃). The structure of MIL-131 or Ti^IIITi^IV(OH)F₄(HPO₄)·(PO₄)·(N((CH₂)₂NH₃)₃) has been determined ab initio from X-Ray synchrotron powder diffraction data using simulated annealing methods and was refined in the triclinic space group P-1 (no. 2). MIL-131 exhibits a one-dimensional structure built up from inorganic chains of corner sharing TiO₅(OH) titanium(III) octahedra and PO₄ and HPO₄ phosphate tetrahedra, related to TiO₂F₄ titanium octahedra. Protonated triamine cations are located between the inorganic motifs, and interact strongly with the mineral network through hydrogen bondings both with terminal fluorine atoms and hydroxo or oxo groups. Multinuclear solid state NMR has allowed a clear attribution of the protons, fluoride, and phosphate groups environment within the framework of MIL-131. The large values of chemical shift anisotropy together with the absence of any ¹³C NMR response confirmed the presence of paramagnetic titanium(III) species deduced from the crystal structure. Finally, 2D MAS ¹H-³¹P CP-HETCOR NMR correlation experiment gives some insight on the nature of the intra-framework hydrogen bonding.Crystal data for MIL-131: a = 14.109(1) Å, b = 8.462(3) Å, c = 7.179(1) Å, α = 93.772(1)°, β = 96.566(2)°, γ = 98.004(1)°, V = 840.36(2) ų, z = 2.     

Mononuclear ruthenium(III) complexes containing chelating thiosemicarbazones: Synthesis,characterization and catalytic property

Mononuclear ruthenium(III) complexes of the type [RuX(EPh₃)₂(L)] (E = P or As; X = Cl or Br; L = dibasic terdentate dehydroacetic acid thiosemicarbazones) have been synthesized from the reaction of thiosemicarbazone ligands with ruthenium(III) precursors, [RuX₃(EPh₃)₃] (where E = P, X = Cl; E = As, X = Cl or Br) and [RuBr₃(PPh₃)₂(CH₃OH)] in benzene. The compositions of the complexes have been established by elemental analysis, magnetic susceptibility measurement, FT-IR, UV–vis and EPR spectral data. These complexes are paramagnetic and show intense d–d and charge transfer transitions in dichloromethane. The complexes show rhombic EPR spectra at LNT which are typical of low-spin distorted octahedral ruthenium(III) species. All the complexes are redox active and display an irreversible metal centered redox processes. Complex [RuCl(PPh₃)₂(DHA–PTSC)] (5) was used as catalyst for transfer hydrogenation of ketones in the presence of isopropanol/KOH and was found to be the active species.