A new crown ether bearing two hydrophobic lateral chains was synthesized and its complexation properties toward divalent metal ions were studied experimentally and theoretically in water and in non-aqueous environment. Electrochemistry and Langmuir film technique were used to evaluate the stability of complexes formed by the ligand with Cu(II), Zn(II) or Ni(II). Molecular modeling allowed unveiling the structure of the complexes. The results obtained show that all three cations form complexes with the crown ether. However, the stability of the complexes is different depending on the cation and on the environment in which they are formed. This observation suggests that cation complexation can be controlled by adjusting solvent properties; it can be useful in view of possible technological and/or medical applications.

Two copper(II) complexes with tetradentate 1,4-disubstituted-1,2,3-triazole ligands, [CuL(MeCN)](ClO4)(2) (1) and [CuL](ClO4)(2) (2), have been prepared and characterized by different techniques, including X-ray structure determination, spectroscopic, and electrochemical measurements, as reported elsewhere. Herein, we report the interactions of these complexes, and corresponding free ligands, with human serum albumin (HSA) verifying their relative thermodynamic stability and differences in binding to this protein. Interactions with HSA were verified by CD measurements monitored at 564nm, up to stoichiometric ratio 2:1 [Complex]:[protein], according to competitive equilibria involving the insertion of copper at the selective N-terminal metal binding site in HSA, and additionally at a secondary nonselective site. Further interactions of these complexes with L-tryptophan residues, and probable supplementary site(s) for the binding, were followed by fluorescence measurements. Analogous experiments with the free L and L indicated much weaker interactions. Protein oxidation damage was observed for both complexes, monitored by carbonyl groups formation in the presence of H2O2, probably with the participation of reactive oxygen species. Density functional theory calculations exhibit metal-ligand binding interaction energies similar to [Cu(HSA-N-terminal)](+), and reinforced the experimental results, showing clearly that such triazole ligands are competitive toward copper(II) in biological medium. [GRAPHICS] .

Interlocked [2]rotaxanes were built from bis-cyclodextrinyl-bis lariats (CD-Ls) and bis-aryl sulfonates by a spontaneous dual cation/anion self-assembling process. Original CD-L's have been synthesized in high yield by a one step “click” or Staudinger–Aza-Wittig (SAW) coupling reaction.

N,N'-Bis(triazoly)diaza[18]crown-6 and Corresponding diaza[15]crown-5 ethers were synthesized by means of click chemistry. The interaction of these ligands with Ni-II, Cu-II, and Zn-II cations were studied by UV/Vis and H-1 and C-13 NNIR spectroscopy. The solid-state structure of Ni-II and Zu(II) complexes formed by the diaza[18]crown-6 ligand were determined by means of X-ray crystallography. The Ni-II complex is centrosyrnmetric; the geometry around the metal ion is slightly distorted octahedral whereby the equatorial sites were occupied by four N atoms, and the axial positions by two O atoms that come from the crown moiety. For the Zn" diaza[18]crown-6 complex, an irregular octahedral coordination was observed whereby the metal ion is asymmetrically placed in the macrocyclic cavity. The equatorial plane is occupied by two N and two O atoms of the crown moiety, and to N atoms of the triazolyl motifs on the pendant arms occupy the axial positions. The diamagnetic character of the Zn" ion allows its structural study in solution by NNIR spectroscopy. A dynamic beh avior was observed at room Lem- perEaure, which coriesporids to the displacement. ion between the bond end and the nonbond end of the macrocycle. This movement results in an S4-symmetrical structure in solution. Quantum chemical calculations at the DFT level have allowed us to interpret the experimental results observed in the solid state for the symmetry of the complexes in terms of covalent and noncovalent interactions, which favor the centrosymmetric and irre. gular octahedral coordination modes, respectively. Only the structure of the Cu-II complex with N,N'-bis(triazolyl)diazal[5]crown-5 ligand has been investigated in the solid state, for which a pentagonal bipyramidal coordination sphere was observed. This coordination geometry was confirmed in solution in MeCN by UV/Vis spectroscopy, and also for the Zn-II complex by NMR spectroscopy. In the case of the Ni-II complex, a structural modification was suggested in solution in MeCN based on the UV/Vis spectrum. The rearrangement of heptadentate coordination to hexadentate is proposed

New cationic polymers were synthesized via radical cyclopolymerization of quaternary diallylammonium monomer salts in a microwave reactor. Co-polymerization was ascertained by H-1- & C-13-nuclear magnetic resonance, differential scanning calorimetry, and average molecular weight estimated via size-exclusion chromatography.Conventional handsheets made from bleached kraft pulps were impregnated with aqueous solutions of selected quaternary ammonium polymers and dried.The hydrophobicity (i.e. dynamic water contact angle, wettability) of samples was significantly enhanced by a bilayer treatment with CMC in the external layer at the saturation level.

The oxidation kinetics at ambient temperature of an ex-cellulose activated carbon cloth has been investigated using an aqueous solution of NaOCl. Oxidized samples were weighed and characterized by TG–TPD–MS and XPS. Weight analysis revealed three stages during the course of oxidation. The first is dominated by the creation of oxygen groups at the carbon surface with an initial oxygen uptake rate assessed at 20mgg−1min−1. The second involves a transfer of oxygenated carbonaceous matter to the liquid phase. The third corresponds to the degradation of the carbon fabric. The diameter of the fibers does not change during the first stage and decreases during the last two stages. The amount of oxygen groups fixed per gram of sample increases with oxidation time during the first two stages, and decreases during the third stage. The creation of oxygen groups progresses from the surface to the bulk. The oxidation degree of carbon atoms (CI–CIII) increases during oxidation. TPD spectra, including for water, have been examined in light of the recent literature and of the temperature-programmed surface reaction theory. The degradation of fibers is interpreted by the aromatic ring cleavage accompanying the creation of carboxylic groups.

Imazamox is an imidazolinone herbicide, a new class of pesticides, which can exist as cationic, anionic or neutral species in water. The adsorption isotherms of Imazamox onto Filtrasorb 400 (F400) activated carbon were determined varying the pH and the ionic strength of the aqueous medium. The results show that ionic strength has no significant effect on Imazamox uptake, contrary to pH, and that F400 has a high affinity for Imazamox. Moreover, it is found that Imazamox adsorbs onto F400 as its neutral form. The best fit of the experimental points is obtained with the Langmuir–Freundlich model, consistent with surface site heterogeneity. Finally, calculating Langmuir–Freundlich isotherms for various constant pH values, it is shown that the two plateaus observed in the experimental isotherms obtained at free pH are due to the variation of the pH along the isotherms.

A threshold thermodesorption method, named fast Intermittent TPD (ITPD), was used to study the evolution of CO(2) and CO arising from the decomposition of oxygen groups at the surface of a porous carbon used in the wastewater treatment.Applied to the as-received carbon, CO(2)-ITPD provided clear evidence for six values of the apparent activation energy of oxygen group decomposition (E(app)): 139, 168, 206, 237, 270 and 290 kJ mol(-1). Corresponding apparent pre-exponential factors (A(app)) were also determined. The data (E(app) and A(app)) derived from ITPD for the six desorption steps allowed a successful description of the complete TPD profile, considering a Gaussian narrow distribution of E(app) for each step. CO-ITPD also showed the presence of six (possibly seven) distinguishable steps upon CO thermal desorption and further demonstrated the interest of the fast ITPD technique for studying carbon surface chemistry.The TPD and ITPD profiles of the carbon treated with sodium hypochlorite showed: (i) a sharp increase in the amount of desorbed species, (ii) the prevailing presence of less stable oxygen groups, mainly carboxylic acids, giving rise to CO(2) desorption at low temperature, and (iii) the progressive merging of the desorption steps detectable at low temperature upon increasing surface density of oxygen groups. (C) 2011 Elsevier Ltd. All rights reserved.

Fluroxypyr is a widely used herbicide whose presence in natural waters has prompted research into its removal by adsorption. This article reports a kinetics study of fluroxypyr adsorption on a commercial activated carbon. The experimental study used a micro differential column batch reactor operated at three solution flow rates and two initial fluroxypyr concentrations, establishing a differential regime in order to obtain correct experimental data. Initial rates at zero coverage permitted the external transfer coefficient k(L) to be calculated. Internal surface diffusion coefficients D-S were determined by using the Homogeneous Surface Diffusion Model running the FAST software and taking advantage of tabulated user-oriented solutions. This model satisfactorily fits the experimental data. DS values were 2.5 x 10(-14) and 4.2 x 10(-14) m(2) s(-1) for initial concentrations of 30 and 50 mg/L, respectively. These values were confirmed by experiments in a widely used shaken batch reactor with a determined kL value.

The synthesis of two 3-deoxy-alpha-L-rhamnosides (i.e., 3,6-dideoxy-L-arabino-hexopyranosides) as models of ascaroside natural products is reported. The present approach is based on a Ferrier rearrangement from L-rhamnal, epoxidation of the resulting glycal and reductive opening of the isolated beta-epoxide. The 3-deoxy-alpha-rhamnoside linked to a long aglycone chain was used to ascertain by Raman vibrational spectroscopy the presence of this peculiar sugar in the inner shell of Ascaris eggs. (C) 2010 Elsevier Ltd. All rights reserved.

The structural model for the title compound, C(16)H(12)N(2)O(2), was refined using a multipolar atom model transferred from an experimental electron-density database. The refinement showed some improvements of crystallographic statistical indices when compared with a conventional spherical neutral-atom refinement. The title compound adopts a half-chair conformation. The amide N atom lies almost in the plane defined by the three neighbouring C atoms. In the crystal structure, molecules are linked by weak intermolecular C-H...O and C-H...pi hydrogen bonds.

The textural characteristics of three commercial activated carbons, Filtrasorb 400 (F400), Industrial React High Affinity and Picabiol, commonly used in water treatment, are reinvestigated. Nitrogen physisorption isotherms are determined in the range P/P 0 = [4 × 10−7–0.998] and processed using BET, αS (Sing), Dubinin–Radushkevich and Density Functional Theory methods. In addition, fractal dimensions are determined by the Frenkel–Halsey–Hill procedure. Since F400 is often considered as a reference material in studies on the adsorption of solutes in aqueous solutions, a review of the textural characteristics of this carbon is carried out. The results obtained in this work using the different methods are consistent and a critical crossed comparison of these results allows discussing the limitations of the methods used. In particular, the impact of the P/P 0 range considered on S BET value is examined. In addition, the accuracy of the BET specific surface area is assessed in the light of information from recent literature.

The synthesis of C-2-symmetric glycophanes incorporating two triazole linkers has been achieved in seven steps from 3,4,6-tri-O-acetyl-D-glucal in good overall yields. The intermolecular Cu( I)-mediated Huisgen reaction was used for the ring closure key-step to give almost exclusively 24-, 26-, and 32-membered chiral macrocycles without significant polymerization. Target compounds however had low solubility in water, precluding investigation of their recognition behaviour in this medium.

Temperature-programmed desorption (TPD) and a differential form of it, called intermittent temperature-programmed desorption (ITPD), turned out to be powerful characterising techniques for chemoresistive materials applied to gas sensing. We investigated samples of SnO2, TiO2 and solid solutions of them (TixSn1 − xO2). TPD and ITPD experiments were carried out in vacuum, with samples previously treated in pure O2 (100 Torr, 500 °C, 30 min). Amounts of desorbed O2 corresponded for all Ti-containing samples to less than 10% of a compact monolayer of ions O2−. Corresponding values of the apparent activation energy of desorption (Eapp) were calculated directly from the Arrhenius plots for each partial TPD and ranged from about 100 to 330 kJ mol− 1 (1.16 to 3.82 eV).

A novel C2-symmetric lariat ether containing two [1,2,3]triazolo-ligands as sidearms was prepared via a click chemistry approach from known N,N′-dipropargyl-4,13-diaza-18-crown-6 (1). The ligand (2) readily forms a stable 1:1-complex with cupric perchlorate. A single crystal structure of the centro-symmetric mononuclear complex (3) could be determined. The CuII center displays a distorted six-coordinated octahedral geometry where two triazoles and two pivot nitrogens constitute the basal plane. The axial positions are occupied by two oxygens of the crown ether part. The cyclic voltammograms of a DMF solution of the complex showed two redox processes in our experimental conditions.

The structural model for the title compound, C 16 H 12 N 2 O 2 , was refined using a multipolar atom model transferred from an experimental electron-density database. The refinement showed some improvements of crystallographic statistical indices when compared with a conventional spherical neutral-atom refinement. The title compound adopts a half-chair conformation. The amide N atom lies almost in the plane defined by the three neighbouring C atoms. In the crystal structure, molecules are linked by weak intermolecular C—H...O and C—H...π hydrogen bonds.

The one-step synthesis of two C2-symmetric receptors including two β-cyclodextrin cores or two disaccharidyl units connected by urea linkers to a diazacrown ether organizing platform is reported. The X-ray structure of the peracetylated bis-ureidocellobiosyl podand could be determined. These molecular systems, long thought to be potent selective carriers for chiral/achiral organic guests at the supramolecular level, were found to be efficient complexing tools toward the Busulfan anticancer agent but also toward l-arginine and l-lysine basic aminoacids.

A differential desorption technique, named intermittent temperature-programmed desorption (ITPD), has been used to get new insights into the properties of La1-xSrxCo0.8Fe0.2O3-delta perovskites. The apparent activation energy of desorption (E-app) and the frequency factor (v) were calculated from ITPD data, for the two distinct oxygen species desorbing from perovskite at temperatures lower than 400 degrees C. The low values (about 10(7)-10(8) s(-1)) obtained for V-app indicated that re-adsorption occurred during the TPD process and therefore that E-app is equal to the Heat of adsorption (E=-Delta H). The first oxygen species, related to lower desorption temperatures, exhibits a distribution of E from 105 to 125 kJ mol(-1). The second one, related to higher desorption temperatures, corresponds to E=146 +/- 4 kJ mol(-1) and 139 +/- 5 kJ mol(-1), for x=0.2 and x=0.3, respectively. The relative amounts of these species contributing to the desorption peak are dependent upon Sr content in the perovskite. (C) 2008 Elsevier B.V. All rights reserved.

Debris samples from braking tests carried out with carbon/carbon discs, mounted in a reduced-scale bench, have been studied by X-ray diffraction, thermogravimetry coupled with mass spectrometry, and N2 physisorption at −196°C. The tests were carried out at low temperature with a high friction coefficient. Two materials with different structural orders (d002=338 and 344nm, respectively) were studied. Debris samples from both materials are similar: they are essentially amorphous and contain up to 10% of oxygen. The specific surface areas are about 180m2/g. However, a careful examination of the experimental results clearly shows some differences depending on the starting materials. Debris from the less ordered material contains fewer carboxylic groups, the specific surface areas of debris obtained from the more ordered material are systematically larger, and debris samples from both materials may be differentiated by the XRD pattern of the small fraction of starting material they contain. Thus, materials with different structural orders yielded similar debris resulting from the severe mechanico-chemical processes involved but retained a slight but clear memory of the material from which they came.