Adsorption of indole and 2-methylindole on ligand-exchange matrix

The adsorption of indole and its 2-methyl derivative from aqueous solutions onto cobalt(II)-carboxylated diaminoethane sporopollenin (CDAE-sporopollenin) was studied using a fixed-bed column at 25+/-0.1 degrees C. Minicolumn adsorption studies showed that the breakthrough and the total adsorption capacities of CDAE-sporopollenin in the concentration range we have studied increased with increasing external ligand concentration. The characteristics of the adsorption process were investigated using Scatchard plot analysis, where the equilibrium binding data for indole on ligand exchanger gave rise to a linear plot. However, for 2-methylindole, divergence from the Scatchard plot was evident, consistent with the participation of secondary equilibrium effects in the adsorption process. The adsorption behaviors of ligands on CDAE-sporopollenin were expressed by both the Langmuir and Freundlich isotherms. The adsorption isotherm data for these ligands on the resin can be satisfactorily fitted to the Freundlich isotherm within the concentration range studied. However, in the case of 2-methylindole, the experimental data did not fit the Langmuir model, especially when a high ligand concentration range is used; this is probably due to the nonspecific interactions between the ligand exchange matrix and the methyl group present. Ligand adsorption constants and correlation coefficients for the ligands were calculated from the Langmuir and Freundlich isotherms.     

Interaction in the ternary complexes of HNO3···HCl···H2O: a theoretical study on energetics, structure, and spectroscopy

Ternary complexes of HNO(3)···HCl···H(2)O were investigated by ab initio calculations with aug-cc-pVDZ and aug-cc-pVTZ basis sets. The results are analyzed in terms of structures, energetics, and infrared vibrational frequencies. In all minima, neither HNO(3) nor HCl becomes ionized. The contribution of the nonadditivity effect, which is significant for hydrogen-bonded clusters, is bigger for the cyclic structures in which HNO(3) acts as a proton donor to HCl, although the global minimum contains HNO(3) donating its proton to a H(2)O molecule.     

Synthesis of Cysteine Modified MoS2 Nanocomposite: A Biocompatible Electrochemical Sensor Material and its Application to the Determination of Antidiabetic Dapagliflozin

Herein, for the first time, a new generation cysteine modified MoS₂ (Cys@MoS₂) based electrochemical sensor was reported. The electrochemical behaviour of dapagliflozin (DAP) was investigated through differential pulse voltammetry (DPV) on the developed sensor (Cys@MoS₂/GCE). The transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR), x‐ray diffraction spectroscopy (XRD) and x‐ray photoelectron spectroscopy (XPS) methods were performed for structural and morphological characterizations of Cys@MoS₂ nanocomposite. On the surface of Cys@MoS₂/GCE, an irreversible anodic peak was observed at 1324 mV. Under the optimal conditions, linear calibration curve with two working ranges between 2.0–60.0 μM and 60.0–110.0 μM were obtained and limit of detection was found to be 1.6 μM. The developed sensor was successfully applied to determine the content of DAP in pharmaceutical sample with satisfying recovery results. It is concluded that Cys@MoS₂/GCE is a reliable, easy to apply and cost‐effective sensor for the routine DAP analysis in pharmaceutical samples.     

Characterization of fresh and aged natural ingredients used in historical ointments by molecular spectroscopic techniques: IR,Raman and fluorescence

Natural organic materials used to prepare pharmaceutical mixtures including ointments and balsams have been characterized by a combined non-destructive spectroscopic analytical approach. Three classes of materials which include vegetable oils (olive, almond and palm tree), gums (Arabic and Tragacanth) and beeswax are considered in this study according to their widespread use reported in ancient recipes. Micro-FTIR, micro-Raman and fluorescence spectroscopies have been applied to fresh and mildly thermally aged samples. Vibrational characterization of these organic compounds is reported together with tabulated frequencies, highlighting all spectral features and changes in spectra which occur following artificial aging. Synchronous fluorescence spectroscopy has been shown to be particularly useful for the assessment of changes in oils after aging; spectral difference between Tragacanth and Arabic gum could be due to variations in origin and processing of raw materials. Analysis of these materials using non-destructive spectroscopic techniques provided important analytical information which could be used to guide further study.     

Synthesis and Structural Studies of 2,2′-[(2E,5E)-hexane-2,5-diylidenedi-nitrilo]-dibenzenethiol and 2-Hydroxybenzaldehyde (2E,5E)-hexane-2,5-diylidenehydrazone ligands and their Mononuclear Cu(II) and Ni(II) Complexes

Monomeric copper(II) and nickel(II) complexes with tetradentate two new ligands, 2,2′-[(2E,5E)-hexane-2,5-diylidenedi- nitrilo]dibenzenethiol(H₂L) and 2-hydroxybenzaldehyde (2E,5E)-hexane-2,5-diylidenehydrazone(H₂L¹) have been synthesized and characterized by elemental analyses, magnetic moments, molar conductance, ¹H-NMR and ¹³C-NMR, IR, mass spectral studies, theoretical calculations (MM2 and AM1) molecular methods. The mononuclear metal complexes of H₂L and (H₂L¹) were found to have a 1:1 metal:ligand ratio. Elemental analyses, stoichiometric and spectroscopic data of metal complexes indicated that the metal ions were coordinated to the sulphur (-SH) and/or (-OH) oxygen and imine nitrogen atoms (C = N). All of the data obtained from spectral, and molecular mechanics (MM2) or semi empirical calculations (AM1) studies support the structural properties of ligands and its Cu(II) and Ni(II) metal complexes.     

Enantioselective transfer hydrogenation of pro-chiral ketones catalyzed by novel ruthenium and iridium complexes of well-designed phosphinite ligand

Abstract

The interaction of [Ru(η⁶-arene)(μ-Cl)Cl]₂ and Ir(η⁵-C₅Me₅)(μ-Cl)Cl]₂ with a new Ionic Liquid-based phosphinite ligand, [(Ph₂PO)-C₆H₉N₂Ph]Cl, (2) gave [Ru((Ph₂PO)-C₆H₉N₂Ph)(η⁶-p-cymene)Cl₂]Cl (3), [Ru((Ph₂PO)-C₆H₉N₂Ph)(benzene)Cl₂]Cl (4) and [Ir((Ph₂PO)-C₆H₉N₂Ph)(C₅Me₅)Cl₂]Cl (5), complexes. All the compounds were characterized by a combination of multinuclear NMR and IR spectroscopy as well as elemental analysis. Furthermore, the Ru(II) and Ir(III) catalysts were applied to asymmetric transfer hydrogenation of acetophenone derivatives using 2-propanol as a hydrogen source. The results showed that the corresponding alcohols could be obtained with good activity (up to 55% ee and 99% conversion) under mild conditions. Notably, [Ir((Ph₂PO)-C₆H₉N₂Ph)(C₅Me₅)Cl₂]Cl (5) is more active than the other analogous complexes in the transfer hydrogenation (up to 81% ee).     

Effect of cationic surfactant adsorption on the rheological and surface properties of bentonite dispersions

In this study, the adsorption, bridging, and intercalation effects of a cationic surfactant, benzyldimethyltetradecyl ammonium chloride (BDTDACl), on bentonite clay suspensions was investigated. The adsorption, rheological behaviors, and colloidal properties of the clay dispersions were determined as a function surfactant concentration. Adsorption isotherms were obtained using the batch-equilibrium technique. The rheological behavior of the clay suspensions was obtained by shear stress-shear rate measurements within 0-350 s-1 shear rates. The structure of the composite particles was analyzed by using X-ray diffraction analysis and it was found that the expansions of basal d-spacings are less than 16.80 A, suggesting a monolayer structure.     

N‐functionalized azolin‐2‐ylidene‐palladium‐catalyzed heck reaction

Novel 1,3‐dialkylimidazolidinium, 1,3‐dialkyl‐3,4,5,6‐tetrahydropyrimidinium, and 1,3‐dialkyl‐1H‐4,5,6,7‐tetrahydrodiazepinium hexafluorophosphates ( 1a–c, 2a–c ) as N‐heterocyclic carbene precursors have been synthesized and characterized. The incorporation of saturated N‐heterocyclic carbenes into palladium precatalysts gives high‐catalyst activity in the Heck coupling of aryl bromide substrates in aqueous media. The complexes were generated in the presence of Pd(OAc)₂ by in situ deprotonation of 1,3‐dialkylazolinium salts 1, 2 . © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:82–86, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20415     

Structural studies and cytotoxic activity of a new dinuclear coordination compound of palladium(II)–2,2′:6′,2″‐terpyridine with rigid dianionic 1,2,4‐triazole‐3‐sulfonate linker

A new dinuclear coordination compound of palladium(II), [Pd₂(terpy)₂(μ‐tas‐N¹,N⁴)]SO₄?11H₂O ( 1 ), was synthesized by tethering a doubly deprotonated 1,2,4‐triazole‐3‐sulfonate (tas) linker generated in situ via oxidation of 1,2,4‐triazole‐3‐thione (tat) under the synthetic conditions. X‐ray diffraction analysis reveals that tat molecules adopt the thione form in the solid state, and are combined in infinite chains by symmetrically related classical intermolecular hydrogen bonds N1─H1???S1, N3─H3???N2 to give rise to R₂²(7) pattern in one‐dimensional chains along the b‐axis propagating along the a‐axis. Further short contacts through lone pairs of N2???S1 on the rings between the adjacent chains along the a‐axis lead to a two‐dimensional network structure. Compound 1 was characterized using infrared, ¹H NMR and UV–visible spectroscopies, electrospray ionization mass spectrometry and X‐ray crystallography. The crystal structure determination of 1 reveals that the Pd(II) ions are coordinated with four nitrogen atoms: three from terpy and one from tas acting as an end‐to‐end (μ‐1,4) bridging ligand. The Pd(II) ions in 1 adopt a distorted square planar geometry. The anti‐growth effect of 1 was tested on colorectal cancer (HCT‐15), non‐small‐cell lung cancer (A549), prostate cancer (PC‐3) and cervical cancer (HeLa) cell lines using sulforhodamine B viability assay. The cytotoxic effect was further confirmed using adenosine triphosphate viability assay. Compound 1 shows a promising cytotoxic activity in the diverse cancer cell models in vitro (p <0.0001).     

Terahertz time domain spectroscopy for the analysis of cultural heritage related materials

A powerful broadband femtosecond laser-driven terahertz source was built and used to analyze cultural heritage and art-related materials in the terahertz region of the electromagnetic spectrum. The high signal-to-noise ratio available in our system revealed details in the absorption spectra which are inaccessible with traditional FTIR spectrometers. Clear spectral signatures were recorded from organic binding media thus demonstrating the potential of the approach for applications in the monitoring and analysis of cultural heritage materials. PACS 42.65.Tg; 87.50.U-; 87.64.K-