J. R. Matos

Inclusion complex of (−)-linalool and β-cyclodextrin

Abstract(−)-Linalool is a monoterpene alcohol which is present in the essential oils of several aromatic plants. Recent studies suggest that (−)-linalool has antimicrobial, anti-inflammatory, anticancer, antioxidant, and antinociceptive properties in different animal models. The aim of this study was to prepare and characterize inclusion complexes of (−)-linalool with β-cyclodextrin (β-CD). Equimolar binary (−)-linalool/β-CD systems were prepared by physical mixture, paste (PM), and slurry methods (SC) and characterized by differential scanning calorimetry, thermogravimetric analysis, FT-IR spectroscopy, X-ray diffractometry, Karl Fisher titration, and scanning electron microscopy. Thermal characterization indicates the occurrence of complexation, mainly in paste complexes, which is present in the interval from 140 to 280xa0°C a gradual mass loss (4.6xa0%), probably related to (−)-linalool loss. FT-IR spectra showed changes that may be related to the formation of intermolecular hydrogen bonds between (−)-linalool and β-CD. The new solid-phase formed using the PM and SC methods, had a crystal structure which was different from the original morphology of β-CD.

Synthesis, characterization, spectroscopy and thermal analysis of rare earth picrate complexes with L-lysine

SummaryRare earth picrate (RE) complexes with L-lysine (Lys) were synthesized and characterized. Elemental analysis (CHN), EDTA titrations and thermogravimetry data suggest a general formula RE(pic)3·2Lys·2H2O, where RE=La-Lu (without Pm) and Y, pic=picrate). IR spectra suggest that Lys is coordinated to the central ion through the nitrogen of the α-amino group. Parameters obtained from the absorption spectrum of the Nd compound indicated that the metal-ligand bonds are essentially electrostatic. Emission spectrum and biexponential behavior of the luminescence decay of the Eu compound suggest the existence of polymeric species. Thermogravimetric/derivative thermogravimetric (TG/DTG) and differential scanning calorimetry (DSC) curves of all complexes are very similar, with five events. The final products are the corresponding rare earth oxides and their X-ray diffraction patterns are identical to the calcinated oxides.

Physical properties of ordered mesoporous SBA-15 silica as immunological adjuvant*

This work reports a detailed analysis of the ordered mesoporous SBA-15 silica synthesis procedure that provides a matrix with mean pore diameter around 10 nm. The encapsulation of bovine serum albumin (BSA) by four different methods allowed the determination of the best imbibition condition, which is keeping the mixture under rest and solvent evaporation. Simulation of the in situ SAXS scattered intensity of the BSA release in potassium buffer solution, gastrointestinal fluids revealed a slow evolution of BSA content, independent of the media. Proton induced x-ray emission results obtained in calcined mouse organs revealed that silica is only present in the spleen after 35 days and is completely eliminated from all mouse organs after 10 weeks. Biological studies showed that Santa Barbara Amorphous-15 is an effective adjuvant when compared to the traditional Al(OH)3, and is non-toxic to mice, rats, dogs and even cells, such as macrophages and dendritic cells. Recent studies showed that the immunological response is improved by enhancing the inflammatory response and the recruitment of immune competent cells to the site of injection as by the oral route and, most importantly, by increasing the number of phagocytes of a particulate antigen by antigen presenting cells.

Synthesis, spectral and thermal studies on dicarboxylate-bridged palladium(II) coordination polymers. Part II

This work describes the synthesis, IR and 13C CPMAS NMR spectroscopic as well the thermal characterization of the new dicarboxylate complexes [Pd2(ox)2(4,4′-bipy)]n (1), [Pd2(ox)2(bpe)]n (2) and [Pd2(ox)2(pz)]n (3) {oxxa0=xa0oxalate, bipyxa0=xa04,4′-bipyridine, bpexa0=xa01,2-bis(4-pyridyl)ethane, pzxa0=xa0pyrazine}. TG experiments reveal that compounds 1–3 undergo thermal decomposition in three steps. Metal palladium was the final product of the thermal decompositions, which was identified by X-ray powder diffraction.

Thermal and spectroscopic characterization of nanostructured zirconia–scandia–dysprosia

Zirconia containing 10xa0mol% scandia and x mol% dysprosia (0xa0≤xa0xxa0≤xa01.5) gels was synthesized by simultaneous precipitation at room temperature. The aim of this work is to verify the effect of dysprosium on the cubic phase stabilization of the zirconia–scandia solid electrolyte. The gel was characterized by thermogravimetry, differential scanning calorimetry, and differential thermal analyses. The thermally treated powders were analyzed by Fourier transform infrared spectroscopy, thermal analyses, and X-ray diffraction techniques. For comparison purpose, a commercial zirconia–10xa0mol% scandia powder was subjected to some characterization techniques. The infrared spectrum shows characteristic absorption bands due to residual material from the synthesis on the surface of the powder particles. Nanostructured powders were obtained after thermal treatments at 500xa0°C for 2xa0h. Infrared spectroscopy and X-ray diffraction results evidence the stabilization of the cubic phase in zirconia–scandia containing dysprosium. The thermal stability of the cubic phase during thermal cycling was ascertained by thermal analysis.

Synthesis And Kinetic Analysis of Poly(2,2'-dymethoxy-4,4'-biphenylenevinylene. A novel conducting polymer

The title polymer was obtained electrochemically by the reduction of 4,4-bis(dibromomethyl)-2,2-dimethoxybiphenyl under very smooth conditions. The DSC and TG/DTG curves registered at four different heating rates showed that the polymer is stable in air up to 150°C, where smooth degradation starts. Above 300°C, decomposition is fast and exothermic (ΔH= –323 J g–1) . The activation energy (116±4 kJ mol–1 ) was determined by Ozawas method.

Luminescence investigation of Dy2O2S and Dy2O2SO4 obtained by thermal decomposition of sulfate hydrate

Abstract The yellow emitting dysprosium oxysulfide (Dy 2 O 2 S) and dysprosium oxysulfate (Dy 2 O 2 SO 4 ) compounds were prepared from the thermal decomposition of hydrated dysprosium sulphate. The materials were characterized by using thermogravimetry (TG/DTG), X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopies. The thermal stability temperatures at around 1151 and 1313 K were determined for the Dy 2 O 2 S and Dy 2 O 2 SO 4 materials, respectively. The photoluminescence properties of the dysprosium oxysulfide were investigated, showing narrow emission bands assigned to the 4 F 9/2 → 6 H J intraconfigurational transitions of the Dy 3+ ion. The yellow emission color of this phosphor suggests that the Dy 2 O 2 S is a promising material for applications in LEDs.

Synthesis, characterization, spectroscopic study and thermal analysis of rare-earth picrate complexes with l-arginine

Abstract Rare-earth picrate complexes with l -arginine were synthesized and characterized. Analysis of carbon, hydrogen, nitrogen and thermal analysis data suggest a general formula Ln(pic) 3 ·2 l -Arg·2H 2 O (Ln=La–Lu, Y, pic=picrate, l -Arg=arginine). IR spectra indicate the presence of water molecules and suggest that l -arginine is coordinated to the central ion through the nitrogen of the amine group. Bands due to picrate ions also indicate that at least in part they are coordinated as bidentate through the phenoxo group and one oxygen of an ortho -nitro group. X-ray diffraction powder pattern results indicate that these complexes are very similar in structure. The parameters obtained from the absorption spectrum of the solid Nd compound indicated that the metal–ligand bonds present weak covalent character. The emission spectra of the Eu compound indicate the existence of different europium coordinaton environments. Thermal analyses results indicated that all the compounds present a similar behavior.

Kinetics of ambuphylline decomposition studied by the incremental isoconversional method

Ambuphylline is a drug obtained by the combination of theophylline and 2-amino-2-methyl-1-propanol. Thermal decomposition of ambuphylline was studied using thermogravimetry and differential scanning calorimetry. Under thermal decomposition, ambuphylline exhibits two degradation steps that are clearly separated. In this paper, the kinetic analysis of the first decomposition step has been carried out by employing the incremental isoconversional method for kinetic analysis based on the orthogonal distance regression. The kinetic parameters of the Arrhenius and Berthelot–Hood temperature functions were evaluated. The results obtained show that the ambuphylline degradation exhibits an induction period for temperatures close to the ambient one. After finishing the induction period, the decomposition proceeds rapidly.

Thermogravimetric study on preparation of NiTiO3 in different reaction times

The thermodynamic properties of the fabrication of NiTiO3 material in different reaction times are reported. The design of this material is accessible through a new efficient sol–gel methods, utilizing Ni(Ac)2·4H2O and Ti(OiPr)4 as starting materials for the formation of NiTiO3 final product through thermal decomposition. The thermogravimetric (TG) and differential scanning calorimetric (DSC) techniques were used to analyze the reaction of Ni(Ac)2·4H2O and Ti(OiPr)4, which produces precursor materials at 0.5, 1, 2, 24, 48 and 72xa0h of reaction times, as well as the thermal stability of these precursors and the final product. The DSC data show an exothermic phenomenon of releasing large amount of energy of −1393xa0J/g at TPeak 655xa0K due to the first event of decomposition started at TOnset 607xa0K and finished at TEndset 663xa0K for the precursor materials obtained at 0.5xa0h of reaction, showing the presence of starting materials in this precursor. A similar exothermic behavior was observed in the sample of 1xa0h of reaction time and was vanished in the materials obtained at 2–72xa0h of reaction, indicating the influence of the time on the completion of reaction and formation of NiTiO3 crystalline phase as final product of thermal decomposition. In addition, using the information obtained from the TG/DSC, XRD and FTIR analyses, the optimum temperature for the thermal decomposition of the precursor materials to NiTiO3 with fairly high crystallinity was also determined and discussed.