Scielo RSS <![CDATA[Journal of the Chilean Chemical Society]]> vol. 54 num. 4 lang. es <![CDATA[SciELO Logo]]> <![CDATA[<b>SYNTHESIS OF POLY (BIBENZIMIDAZOLE-P-PHENYL- BENZOBISOXAZOLE)</b>]]> A diacid monomer of benzobisoxazole 2, 6-di(p-phenylene-carboxylic) acid (BBODPA) was synthesized in a simple procedure, and characterized by means of FTIR, ¹H NMR and 13C NMR. The resulting BBODPA was polymerized with 3, 3'-diaminobenzidine tetrahydrochloride (DAB) to prepare poly (bibenzimidazole-p-phenyl-benzobisoxazole) (PBBIBBO) in polyphosphonc acid. The inherent viscosities values of PBBIBBO indicated that it was a kind of high molecular weight polymer. The structure of PBBIBBO was confirmed by ¹H NMR, 13C NMR and FTIR. Thermal properties and dissolubility of PBBIBBO were also investigated. These results showed that PBBIBBO exhibited good thermal stability. <![CDATA[<b>COPPER ELECTROWINNING BASED ON REACTIVE ELECTRODIALYSIS</b>]]> This paper shows an alternative to the classic electro winning copper process using a cell based on reactive electrodialysis, which consists of two compartments separated by an anionic membrane, one of which contains the copper sulphate catholyte, where the cathode is located, and the other compartment contains the ferrous sulfate anolyte, where the anode is located. In this type of cell the anodic reaction is the oxidation of iron (Fe2+ to Fe3+), which consumes less energy than the classic water oxidation. Moreover, this new anodic reaction does not produce acid mist. <![CDATA[<b>INVESTIGATIONS ON NUCLEASE ACTIVITY OF </b><i>TRANS <b>MIXED </b></i><b>LIGAND- COPPER(II) COMPLEXES WITH ORTHO SUBSTITUTED AROMATIC OXIMES AND HETEROCYCLIC BASES</b>]]> Mixed ligand complexes of copper(II) with salicyladoxime (SAO), 2-hydroxy acetophenone oxime (HAO) as primary ligands and pyridine( Py), imidazole (Im) as secondary ligands have been synthesized and characterized by molar conductivity, magnetic moments, electronic, IR and ESR spectral data. Cyclic voltammetric studies show quasi-reversible reduction attributable to Cu2+/ Cu+. The binding interactions between metal complexes and calf thymus DNA have been investigated by using UV -Visible titrations and cyclic voltammetry studies. The cleavage activity of complexes was carried out on double-stranded pBR322 circular plasmid DNA by using gel electrophoresis. All complexes show increased nuclease activity in the presence of oxidant (H(2)0(2)). The nuclease activity of mixed ligand complexes are compared with that of the parent copper(II) complexes. Controlled experiments suggest that the complexes cleave DNA predominantly via an oxidative mechanism. <![CDATA[<b>INFLUENCE OF BATH TEMPERATURE AND PH VALUE ON PROPERTIES OF CHEMICALLY DEPOSITED CU<sub>4</sub>SNS<sub>4</sub> THIN FILMS</b>]]> Thin films of Cu4SnS4 semiconductors were prepared by chemical bath deposition technique in aqueous solutions. The effects of various bath temperatures (40, 50 and 60 °C) and pH values (pH 0.5, pH 1.0 and pH 1.5) on growth of films were reported. The structure and morphology characteristics of thin films of Cu4SnS4 grown on indium tin oxide glass substrates were investigated by X-ray diffraction and atomic force microscopy techniques. The optical properties were measured to determine the transition type and band gap value. The thin films produced were found to be polycrystalline with orthorhombic structure. The X-ray diffraction data showed that the most intense peak at 2θ = 30.2° which belongs to (221) plane of Cu4SnS4. The films deposited at 50 °C were found to have the best photoresponse activity and smaller crystal size. At pH 1.5, the film showed well-covered entire substrate surface and the highest absorption values in AFM and optical study, respectively. The best condition to prepare good quality thin films can be carried out at 50 °C with pH 1.5. The bandgap value was found to be 1.4 eV with direct transition. <![CDATA[<b>THERMAL STABILITY AND KINETIC STUDIES OF COBALT (II), NICKEL (II), COPPER (II), CADMIUM (II) AND MERCURY (II) COMPLEXES DERIVED FROM N-SALICYLIDENE SCHIFF BASES</b>]]> The thermal properties of a number of Schiff base metal complexes in nitrogen atmosphere have been investigated by thermogravimetry (TG) and differential thermogravimetry (DTG). The kinetic analyses of the thermal decomposition were studied using the Coats-Redfern and Horowitz-Metzger equations. The obtained kinetic parameters show the kinetic compensation effect. <![CDATA[<b>SYNTHESIS, STRUCTURAL CHARACTERIZATION AND ANTIMICROBIAL STUDIES OF NOVEL SCHIFF BASE COPPER(II) COMPLEXES</b>]]> Five novel copper(II) complexes have been synthesized using Schiff base ligands, synthesized by the condensation reaction of anthranilic acid and Knoevenagel β-ketoanilide condensates (obtained by the condensation of acetoacetanilide and substituted benzaldehydes). The ligands and copper(II) complexes have been characterized on the basis of Microanalytical, Mass, UV-Vis., IR, 'H NMR, ESR, XRD and CV spectral studies, as well as magnetic susceptibility and conductivity data. On the basis of spectral studies, a square-planar geometry has been proposed for the copper(II) complexes. From the XRD data, the CuL-1 complex has the crystallite size of 50 nm respectively. The in vitro antimicrobial activity of the compounds is tested against the bacteria Escherichia coli, Salmonella typhi, Staphylococcus aureus, Klebsiella pneumoniae and Pseudonomas aeruginosa and fungi Aspergillus niger, Rhizopus stolonifer, Aspergillus flavus, Rhizoctonia bataicola and Candida albicans by well diffusion method. The complexes show stronger antimicrobial activity than the free ligands. They represent a novel class of metal-based antimicrobial agents which provide opportunities for a large number of synthetic variations for modulation of the activities. <![CDATA[<b>A RP-HPLC METHOD FOR THE SIMULTANEOUS DETERMINATION OF DILTIAZEM AND QUINOLONES IN BULK, FORMULATIONS AND HUMAN SERUM</b>]]> High Performance Liquid Chromatographic method was developed and applied for the simultaneous determination of diltiazem and fluoroquinolones in bulk, pharmaceutical formulations and human serum in presence of caffeine as internal standard. A Hiber®, RP-18 column was used with mobile phase consisting of acetonitrile:methanol:water (30:20:50 v/v, pH 3.6) and quantitative evaluation was performed at 230 run. Suitability of this method for the quantitative determination of the drugs was proved by validation in accordance with the requirements laid down by International Conference on Harmonization (ICH) guidelines.The method was selective, precise, accurate and can be used for routine analysis of pharmaceutical preparations, quality control and clinical laboratories. <![CDATA[<b>ESSENTIAL OIL COMPOSITION AND ANTIMICROBIAL ACTIVITY OF FRUITS OF <i>Iryanthera ulei </i>W. FROM COLOMBIA</b>]]> The essential oil was obtained by steam distillation from fruits of Iryanthera ulei Warb. growing in Colombia. The oil was analyzed by GC/FID and GC/ MS. The main components were a-muurolol (13.2%), spathulenol (12.1%), a-cadinol (7.8%), guaiol (4.0%), oplopanone (3.7%), 1,10-diepi-cubenol (3.4%) and limonene (3.3%) constituting a sesquiterpene-type enriched mixture. In addition, oil was tested for its antimicrobial activity against some Gram-positive and Gram-negative bacteria by means of a modified agar-well diffusion method. S. aureus strain was found to be the most sensitive microorganism. <![CDATA[<b>PREPARATION OF MANGANESE DIOXIDE MODIFIED GLASSY CARBON ELECTRODE BY A NOVEL FILM PLATING/CYCLIC VOLTAMMETRY METHOD FOR H<sub>2</sub>0<sub>2</sub> DETECTION</b>]]> Manganese dioxide modified glassy carbon electrode (Mn0(2)/GC) was prepared by a novel film plating/cyclic voltammetry method for the determination of H(2)0(2). A manganese film was first cathodically deposited on the surface of glassy carbon electrode from MnCl2 solution at the potential of-1.4 V versus Ag/ AgCl (satd. KC1), and then a well defined manganese dioxide was deposited on the surface of glassy carbon electrode by cyclic voltammetry at potential range -0.6 ~ 0.6 V, scan rate 100 mV s-1 in 0.1 mol L7¹ NaOH solution. The resulted modified electrode was characterized by cyclic voltammetry and scanning electron microscopy (SEM), which showed excellent electrocatalytic activity for the oxidation of H(2)0(2). The chronoamperometric detection of H(2)0(2) was carried out at 0.6 V in phosphate buffer solution pH 7.38 containing 0.1 mol L7¹ KC1 and the linear relationship of response current on H(2)0(2) concentration was obtained in the range from 4. Ixl0~10 to lxl0~-mol L-1 with a minimum detectable concentration of 3xl0~10 mol L7¹ [S/N (signal noise ratio) = 3]. The response time of the electrode to achieve 95% of the steady-state current was < 2 s. No measurable reduction in analytical performance of the modified electrode was found by storing the electrode in ambient conditions for 30 days. This modified electrode has many advantages such as simple preparation procedure, remarkable catalytic activity, good reproducibility and long term stability of signal response during hydrogen peroxide oxidation. The deposition of manganese dioxide on the surface of GC appears to be a highly efficient method for the development of a new class of sensitive, stable and reproducible hydrogen peroxide electrochemical sensor. <![CDATA[<b>SYNTHESIS, CHARACTERIZATION AND ANTI-MICROBIAL ACTIVITY OF NEW STEROIDAL CHOLEST-5-EN-7-ONE DERIVATIVES FUSED WITH SUBSTITUTED PYRAZOLINE RING</b>]]> The reaction of cholest-5-en-7-one (1), its 3β-acetoxy (2) and 3β-chloro (3) analogues with thiosemicarbazide in sodium ethoxide affords 2'-thiocarbamoyl-cholest [5,7-cd] pyrazoline (4), 2'-thiocarbamoyl-3β-acetoxycholest [5,7-cd] pyrazoline (5), and 2'-thiocarbamoyl-3β-chloro cholest [5,7-cd] pyrazoline (6), respectively. The structures of the newly synthesized compounds have been established on the basis of physical, analytical and spectral data. Their antibacterial activities were tested in vitro by disk diffusion assay against Gram-positive and Gram-negative bacterial strains of bacteria. <![CDATA[<b>ADSORPTION OF MULTIWALLED CARBON NANOTUBES ON ELECTROSPUN POLYCAPROLACTON NANOFIBERS</b>]]> Polycaprolacton (PCL) and multiwalled carbon nanotubes/PCL (P-MWNT/PCL) were prepared by electrospinning technique. The average diameter of the nanofibers was below 400 nm. The mechanical properties of the P-MWNT/PCL nanofibers were higher than that of neat PCL nanofibers. It was also found that the mechanical properties of the composite nanofibers were decreased as increased the amount of P-MWNTs, which were due to the poor dispersion of the P-MWNTs in the PCL matrix or agglomeration of MWNTs at high concentration. The thermal stability of the P-MWNT/PCL nanofibers was higher than PCL nanofibers. The conductivity of the adsorbed P-MWNT on PCL (<p) nanofibers was 1.27 x 10-4 S/cm. <![CDATA[<b>COMPOSITION AND BIOLOGICAL ACTIVITY OF THE ESSENTIAL OIL OF PERUVIAN <i>LANTANA CAMARA</i></b>]]> The composition of the essential oil from Pantana cámara L. (Verbenaceae) obtained by hydrodistillation of the aerial parts was examined by GC, GC/ MS, and 13C-NMR. The GC analysis showed that carvone is the most abundant monoterpene 75.9%, together with limonene 16.9%, accounting for 92.8% of the oil. The major components were also tested by "C-NMR analysis of the essential oil. The L. cámara oil was assayed against several microorganisms, showing moderate antibacterial activity against the human pathogen Staphylococcus aureus (MIC 200 µg/ml). High antioxidant activity evaluated by the Trolox equivalent antioxidant capacity assay (TEAC) was found (29.0 mmol Trolox/kg) and relative low anti-inflammatory activity due to its weak ability for inhibiting lipoxygenase (IC50 = 81.5 µg/ml). <![CDATA[<b>MECHANISTIC INVESTIGATION OF OXIDATION OF SOME AMINO ACIDS BY BIS(DIHYDROGEN TELLURATE)ARGENTATE(III) ION IN ALKALINE MEDIUM</b>: <b>A KINETIC STUDY</b>]]> The oxidation of leucine, isoleucine and valine by bis(dihydrogen tellurate)argentate(III) ion was studied by stopped-flow technique. It was both first order with respect to Ag(III) complex and amino acids. A plausible mechanism was proposed form the kinetics study. And the rate equations derived from mechanism can explain all experimental phenomena. The activation parameters along with the second order rate constants were calculated. <![CDATA[<b>UNVEILING THE STRUCTURE OF NI/NI OXIDE NANOPARTICLES SYSTEM</b>]]> This report shows the structural analysis study of the 30-50 nm Ni/Ni oxide nanoparticles obtained by displacement of a nickel-organometallic complex. So using techniques as electron diffraction (ED), and X-ray diffraction it was shown the presence of Ni2O3, NiO, NiO2, and nickel phases on it. <![CDATA[<b>FATTY ACID IN ECTOPARASITE COPEPODS FROM SOUTHERN CHILE <i>CALIGUS ROGERCRESSEYI </i>BOXSHALL & BRAVO 2000, <i>LEPEOPHTHEIRUS MUGILOIDIS </i>VILLALBA & DURAN 1985 AND THE FREE-LIVING SPECIES <i>TIGRIOPUS </i>SP</b>]]> This work presents the fatty acid composition of copepod species in southern Chile: two of them that are ectoparasites on Eleginops maclovinus (Caligus rogercresseyi and Lepeophtheirus mugiloidis) and one free-living species (Tigriopus sp.). C. rogercresseyi females from different hosts (Salmo salar and E. Maclovinus). Fatty acid methyl esters were determined with GC-MS. The studied species presented a wide variety of saturated, monounsaturated, and polyunsaturated fatty acids, with compounds having from 12 to 24 carbons. The studied species had different percentage compositions of the acids identifed. In all three species, palmitic (C16) and oleic (C18:1) fatty acids dominated the percentage concentrations. The highest percentage concentration (46.59 %) was found for palmitic acid in Tigriopus. Only the females of C. rogercresseyi analyzed were found to have myristoleic acid (C14:1). Stearic (C18) and oleic (C18:1) acids were present in both C. rogercresseyi males and females, but with different distributions. Oleic acid in females was 33.97 % and only 7.64 % in males, whereas stearic acid was 9.95 % in females and 21.51 % in males. The C. rogercresseyi on Patagonian blennie (Eleginops maclovinus) revealed 3.89% C20:4 and 9.60 % C20:5. Eicosapentaenoic and docosahexaenoic acids, detected only in the ectoparasitic copepods, had percentage concentrations of up to 10 %. The possible role of this fatty acid in the stimulation of innate fsh immunity is discussed. <![CDATA[<b>THERMOSENSITIVE POLY(N-ISOPROPYLACRYLAMIDE)-<i>B</i>-POLYCAPROLACTONE-<i>B</i>-POLY(N-ISOPROPYLACRYLAMIDE) TRIBLOCK COPOLYMERS PREPARED VIA ATOM TRANSFER RADICAL POLYMERIZATION FOR CONTROL OF CELL ADHESION AND DETACHMENT</b>]]> Stimuli-responsive polymer materials have potential uses in drug delivery, tissue engineering, bioreactors, and cell-surface adhesion control. Temperature-responsive surfaces of triblock copolymers of poly(N-isopropylacrylamide)-b-polycaprolactone-b-poly(N-isopropylacrylamide) (P(NIPAAm)-b-PCL-b-P(NIPAAm)) were fabricated via atom transfer radical polymerization (ATRP). At 37 °C [above the lower critical solution temperature (LCST) of NIPAAm of 32 °C], the seeded cells adhered on the surface of the triblock copolymer, while below the LCST the cells detached from the surface spontaneously. P(NIPAAm) acted as the thermoresponsive segments of the triblock copolymer for control of cell adhesion and detachment. The thermosensitive copolymers are potentially useful as stimuli-responsive adhesion modifers for cells in biomedical felds. <![CDATA[<b>INCREASE OF TOTAL GLUTATHIONE AS A RESPONSE TO CD INDUCED STRESS IN A CHILEAN ENDEMIC BRYOPHYTES (<i>THUIDIUM </i>SP.)</b>]]> Bryophytes collected from the IV Region of Chile, were treated with CdCl2 to stimulate the synthesis of phytochelants. After cadmium treatment, total peptides were extracted from the plants and were analyzed using HPLC to search for the presence of phytochelatin molecules. Chromatography results showed the absence of phytochelatin-like molecules in bryophytes. However, glutathione and a molecule suspected to be γ-glutamil-cistein were detected. The latter compound is knowed to be involved in the metabolic pathway of the gluthatione and phytochelatin synthesis. The results indicated the absence of detectable phytochelatins in bryophytes containing heavy metal as contaminants. The increase in glutathione during the experimental period may have been due to a response to oxidative stress. Thus this work suggests an important role of the glutathione in the detoxifcation mechanisms of bryophytes. <![CDATA[<b>DETERMINATION OF LOW MOLECULAR WEIGHT CARBOHYDRATES IN CABERNET SAUVIGNON RED WINES</b>]]> Low molecular weight carbohydrates (LMW) were determined in a Chilean Cabernet Sauvignon red wine by the Dubois method, a specifc method for the determination of carbohydrates. Dialysis treatment of red wine allowed the separation of pentoses, hexoses, reducing and non-reducing oligosaccharides and glycosides (LMW) from the polysaccharides fraction (HMW) fraction. The total sugar content of red wine by Dubois method was 5.55 g/L. The content of LMW sugars determined by Dubois method (3.63 g/L) is higher than the sugar content of the polysaccharides fraction (1.78 g/L). Analysis of twenty more samples of Cabernet Sauvignon red wines showed that the high molecular weight fraction content is quite iterative (mean value 2.50 g/L). The advantage of the Dubois method in relation to Fehling method is that the former does not need prior decolouration of the sample and there is not interference of aldehydes. The method developed in this work may be a complementary method for the determination of carbohydrates in wine industry. <![CDATA[<b>INHIBITION OF CORROSION OF </b><b><i>Α</i></b><b>-BRASS (Cu-Zn, 67/33) IN HNO<sub>3</sub> SOLUTIONS BY SOME ARYLAZO INDOLE DERIVATIVES</b>]]> The infuence of some arylazo indole derivatives on the corrosion rate of 70/30 a-brass in 2 mol 1-1 HNO3 was investigated using weight loss and galvanostatic polarization techniques. It was found that the investigated compounds behave as inhibitors. The inhibition effciency increases with increasing the inhibitor concentration, but decreases with increasing the temperature. The adsorption of these compounds on the a-brass surface follows a Frumkin’s adsorption isotherm. The electrochemical results indicated that all the investigated compounds act as mixed-type inhibitors. The infuence of the substituent group on the inhibition effciency of the inhibitor was explained in terms of the density of the electron cloud on arylazo indole moiety. Some thermodynamic parameters for corrosion and adsorption processes were determined and discussed. <![CDATA[<b>A FAST, ROBUST ELECTROCHEMICAL METHOD FOR THE AUTOMATED DETERMINATION OF HYDROGEN PEROXIDE</b>]]> A suitable fow-injection method for the analysis of commercial solutions of hydrogen peroxide is described. A Nafon-coated glassy carbon electrode, modifed by deposition of copper hexacyanoferrate (CuCHF), is employed as an amperometric sensor. The method allows the analysis of 45 samples per hour, with peroxide concentrations in the range of 1.25 -10.0 mM, with relative standard deviations smaller than 1%. <![CDATA[<b>SYNTHESIS OF A-RING-SUBSTITUTED 5,6,8,12B-TETRAHYDROISOINDOLO[1,2-<i>A</i>]ISOQUINOLIN-8-ONES</b>]]> The synthesis of 4,5,8,12b-tetrahydroisoindolo[1,2-a]isoquinolin-8-ones is reviewed The unsubstituted parent compound, a series of fourteen A-ring-substituted derivatives, most of them new, and some of their doubly benzylic, 12b-hydroxylated oxidation products were synthesized. Unusual features of their reactivity are briefy discussed. <![CDATA[<b>DETERMINATION OF GABAPENTIN IN BULK DRUG AND IN PHARMACEUTICAL DOSAGE FORM BY HPLC METHOD</b>]]> This paper describes validation of the selective, precise and accurate isocratic HPLC method for the assay of Gabapentin as bulk and pharmaceutical dosage forms. The mobile phase composition was ammonium dihydrogen orthophosphate buffer and methanol in 60:40(v/v) proportions Column used was strong cation exchange column bonded with phenyl sulphonic acid. Quantitation was achieved by UV detection at 200 nm. A linear response (r² ≥ 0.999) was observed in the range of 2.5 mg/mL -7.5 mg/mL. The method shows good recoveries (Average 101.2%) and the relative standard deviation intra and inter-day were found to be less than 0.5 %. Validation parameters were also determined. The method can be used for quality control assay of Gabapentin as bulk and in fnished dosage form and for the stability studies as the method separates Gabapentin from its degradation products and excipients. <![CDATA[<b>SYNTHESIS OF DIBENZYLBUTANEDIOL LIGNANS AND THEIR ANTI-HIV, ANTI-HSV, ANTI-TUMOR ACTIVITIES</b>]]> An effcient route to the synthesis of dibenzylbutanediol lignans and their analogues was reported. The syntheses were based on a strategy involving Stobbe condensation and alkylation reaction to give the skeleton of lignan, the resolution of (±)-diacid with quinine, the transformation of functional groups to obtain seven dibenzylbutanediol lignans and one analogue. Among the synthesized lignans, four compounds were natural products. All dibenzylbutanediol lignans and their analogue synthesized were evaluated on HIV Tat transactivation in human epithelial cells, HSV-1 gene and human leukemic, liver, prostate, stomach, and breast cancer cell in vitro, but some compounds displayed weak activity against HIV, HSV and MDA-MB-435 human breast cancer cell. <![CDATA[<b><i>IN VITRO </i></b><b>EVIDENCES FOR SIMVASTATIN AND LOSARTAN POTASSIUM INTERACTION AND ITS <i>IN VIVO </i>IMPLICATIONS</b>]]> In the present paper, we describe the in vitro availability of simvastatin, a potent HMG-CoA reductase inhibitor, in presence of losartan potassium, which is a non-peptide angiotensin II receptor antagonist. These studies were carried out at 37, 48 and 60°C in different pH environments simulating human body compartments. The reactions were studied by UV spectroscopy and the availability of both drugs in presence of each other was determined by deriving a simultaneous equation for two component system through modifcation of Beer`s law. The interactions were further characterized by IR and H¹NMR spectroscopic techniques. It was observed that availability of simvastatin in presence of losartan at 37 ºC in simulated gastric juice, at pH 7.4 and pH 9.0 was blocked by losartan through the formation of a charge-transfer complex while the availability of losartan in turn was immensely increased. In pH 4.0 these effects were reversed, availability of simvastatin increased and the availability of losartan was depressed. Similar results were observed at higher temperatures. <![CDATA[<b>ARISTOLOCHIC ACIDS FROM ARISTOLOCHIA BRIDGESII, A HOST-PLANT OF BATTUS POLYDAMAS ARCHIDAMAS</b>]]> The present study confrms the hypothesis that aristolochic acids are present in Aristolochia bridgesii. The chemical composition of aristolochic acids in this species is qualitatively similar to that of Aristolochia chilensis, with the two species differing only in the total amount of aristolochic acids present, and in the relative proportions of each aristolochic acid. These results are consistent with the fact that the two Aristolochia species in Chile both serve as host plants to Battus polydamas archidamas (Lepidoptera, Papilionidae, Troidinii). <![CDATA[<b>EFFECT OF THIOUREA CONCENTRATION ON THE ELECTROCHEMICAL BEHAVIOR OF GOLD AND COPPER ELECTRODES IN PRESENCE AND ABSENCE OF Cu(II) IONS</b>]]> The effect of thiourea (TU) concentration on copper electrodeposition was studied employing cyclic voltammetry and electrochemical crystal quartz microbalance techniques. It was found that the polarization effects are related to the type of species generated in the electrode interface. Due to formation of formamidine disulfde (FDS) at concentrations greater than 10-4 mol dm-3, the electrode surface is blocked, and copper electrodeposition shifts towards more negative potential values (polarizing effect). Lower concentrations favors the formation of Cu(I) -TU contributing to the de-polarization of copper electrodeposition reaction. <![CDATA[<b>PREPARATION OF CE<sub>0.8</sub>GD<sub>0.2</sub>O<sub>1.9</sub> SOLID ELECTROLYTE BY THE SOL-COMBUSTION METHOD</b>]]> Ce0.8Gd0.2O1.9 (GDC) powders were prepared by a novel sol-combustion method using citric acid as the chelating reagent. The effects of different sintering temperatures were investigated on the evolution of crystalline phase, particle size, and lattice parameters of the resulted GDC powders. The results have shown that ultrafne GDC powders of around 40nm in diameter were successfully prepared by the sol-combustion technique. The powders showed a high sinterability, and a relative of 95.2% of the theoretical density was obtained at a sintering temperature of 1250ºC. Electrochemistry measurements showed that the GDC ceramics had relatively high oxygen ionic conductivity in low-temperature range. <![CDATA[<b>CHITOSAN-COPPER PAINT TYPES AS ANTIFOULING</b>]]> A prototype of antifouling paints was prepared with a QS-Cu (I)-Fe (II) complex as a possible replacement for traditional antifouling paints, which contain a large concentration of copper, fnding them in an order of 10 - 30 % depending on the brand, and if it is water or solvent based. A Qs-Cu complex was prepared, with a solution at 3% with acetic acid, and then Fe2O3 was added to the solution. FT IR analysis was carried out, as well as analysis of the TGA at the Qs and the complex with Qs-Cu, and with the solution, three different paints were prepared. Those that varied volumen of diethylene glycol added to them. The analysis of the paints was carried out, once the paint was pervaded in a network of polyamide, through SEM with EDX and TEM, which was purchased with the commercial paints, water based and solvent based. One of the objectives is to be able to compare the coverage of the network with the commercial paint, and that of the complex QS-Cu. The results showed that the best paint obtained was paint #2, found to be similar to that pervaded with water based paint. <![CDATA[<b>ASSESMENT OF TRACE ELEMENTS AND MOBILITY OF ARSENIC AND MANGANESE IN LAGOON SEDIMENTS OF THE HUASCO AND COPOSA SALT FLATS, CHILEAN ALTIPLANO</b>]]> Total concentration of Fe, Mn, Zn, Cu, Cr, Cd, As, Sb and Se in lagoon sediments found in the Huasco and Coposa salt fats, Chilean Altiplano and the mobility of As and Mn by means of a simple extraction methodology was studied. The optimum digestion was made with HCl:HNO3 3:1, and the detection of elements, by means of FAAS, ET-AAS, HG-AAS and HG-AFS techniques. Sediments contain a high concentration of As, which ranges from 43 to 268 mg Kg-1 but low concentration in the majority of other elements with different proportions depending on the date of sampling. Huasco presented the greater enriched condition and the concentration of Mn was approximately nine times higher. The greater mobility of As species was obtained in the metalloid’s higher accumulation season. The extracting solutions of: 0.11M HOAc; acetate buffer in the ratio of 1 to 50; and, double-phase extraction in the ratio of 1 to 25, presented the same effciency. Because of the high concentration of As, it is not possible to obtain the same mobility, when a acetate buffer in the ratio of 1 to 25 is employed. The 100% quantitative extraction was achieved by using 0.43M HOAc and a solution of 0.25M H2SO4. The removal of As oxalate buffer, depends on the origin and, the content of Fe and Mn in the sample. When the oxalate buffer is employed Huasco presented a higher mobility (61 and 67%) than Coposa (37%). Sediments do not present any soluble salts of Mn in water. The percentage of Mn extracted with 0.11M HOAc, and any of the other three extracting solutions, is much higher in Huasco. However, when using 0.25M H2SO4, this tendency becomes inverted exhibiting less mobility in Huasco (45 - 88%) than in Coposa (63 - 99%). <![CDATA[<b>STRUCTURE AND THERMAL PROPERTIES OF LIGNINS</b>: <b>CHARACTERIZATION BY INFRARED SPECTROSCOPY AND DIFFERENTIAL SCANNING CALORIMETRY</b>]]> After cellulose, lignin is, the second most abundant component in wood. In the pulping industry, the introduction of modern Kraft pulping technologies could produce chemical modifcation in lignin’s functional groups. Kraft lignins from Eucaliptus nitens and Pinus radiata industrial black liquors were isolated by acid precipitation. An organosolv lignin was obtained from spent liquor from the P.radiata wood pulping process. All lignins were acetylated with acetic anhydride and characterized by Fourier-transformed infrared spectroscopy (FT-IR) . Analysis based on the IR-fngerprint spectral region indicates several differences in the functional groups of the different types of lignins. The thermal behaviour of unmodifed and acetylated lignins were studied by differential scanning calorimetry (DSC) and the glass transition temperatures (Tg) were determined and compared with values reported in the literature. The acetylated lignins show a decrease in the Tg values which is probably due, to the at plasticization effect of the acetylation reaction. <![CDATA[<b>THALLIUM LEVELS AND BIOACCUMULATION IN ENVIRONMENTAL SAMPLES OF NORTHERN CHILE</b>: <b>HUMAN HEALTH RISKS</b>]]> Thallium (Tl) is a highly toxic heavy metal; however there is an increasing demand for thallium in the high-technology and a lack of information in the literature. On the other hand, under natural conditions, Tl occurs in large quantities rarely and plays no role in the metabolism of plants or animal. Studies on the presence of Tl in the vicinity of a copper mining-impacted region in northern Chile were carried out. A number of different types of environmental samples such as crop plants (potato, broad bean and maize), water, algae (Myriophyllum acuaticum, Zannichellia palustris L.) and one plant species (Tessaria absinthioides) growing wildly in the same area, were examined. All of them are exposed to a natural environmental contamination and to the impact of the copper mining activity throughout the region. Thallium concentration in plants exhibits species-dependent preferences. Thus, the enrichment of Tl in the edible parts of crop species decreases in the following order: potato > broad bean > maize grain. Thallium contents, expressed as dry weight (d.w.), varied from < 0.001 to 6.8 µgg-1 in crop plants, from 0.295 to 8.3 µgg-1 in algae, and between 0.010 and 0.501 µgg-1 in plant samples (2-10 times the level normally found in plants, 0.05 µgg-1 dry wt). Dissolved T1 concentrations in rivers were found to be 6 to 120 ngL-1. In the current study, the risk for adverse health effects derived from ingestion from potatoes was assessed. It shows that there is an important risk for the infantile and adult population at present. <![CDATA[<b>SYNTHESIS AND STRUCTURAL DETERMINATION OF A NEW CHALCONE 1,5-BIS(3-METHYL-2-THIENYL)PENTA-1,4-DIEN-3-ONE, C<sub>15</sub>H<sub>14</sub>OS<sub>2</sub></b>]]> This is a structure in a family concerning new polythiophene derivatives. This kind of compounds, a chalcones, has interesting aspects about its intermolecular interactions, of varied type (C15H14OS2) and strength. In the case of the title compound, C15H14OS2, interactions of all three types generate a rather compact, evenly connected 3D structure. <![CDATA[<b>A NOVEL SYNTHESIS OF SUBSTITUTED 4-HYDROXY- 1,8-NAPHTHYRIDINES</b>]]> Michael addition of 2-aminopyridines with methylpropiolate to afforded the addition compound 1a-g, which on further cyclisation at higher temperature in dowtherm-A to yield cyclised product 2 a-g, with respective yields depends on the nature of the substituents. <![CDATA[<b>CHEMICAL COMPOSITION OF ESSENTIAL OIL OF <i>BACCHARIS SALICIFOLIA </i>(RUIZ & PAVON) PERS. </b><b>AND ANTIBACTERIAL ACTIVITY</b>]]> The essential oil of the aerial parts of Baccharis salicifolia was examined by GC and GC-MS and the major components were identifed as α-pinene, camphene, β-pinene, α-phellandrene, α-cubebene, β-cariophyllene, 6,9-guaiadiene, germacrene D and germacrone. The essential oil was tested against eight Gram positive and Gram negative bacteria. The essential oil was found to exhibit moderate antibacterial activity against Gram positive bacteria tested with MIC values from 0.47 to 0.94 (µg/ml). <![CDATA[<b>ANTIMICROBIAL AND ANTIOXIDANT COMPOUNDS FROM THE INFUSION AND METHANOLIC EXTRACT OF <i>Baccharis incarum </i>(WEDD.) PERKINS</b>]]> In the traditional medicine of the South American highlands, the infusion and decoction of aerial parts of “tola”, Baccharis incarum (Wedd.) Perkins (Asteraceae) is orally taken as an antiseptic, antipyretic and digestive or externally applied to relieve pain and infammation. A plant infusion and methanolic (MeOH) extract of the aerial parts were compared for main constituents by HPLC-MS as well as assessed for antimicrobial and free radical scavenging activities. Assay-guided fractionation of the polar extracts was carried out using the ABTS•+ autographic as well as methicillin-resistant Staphylococcus aureus and Enterococcus faecalis bioautographic test. Seven compounds were isolated from the polar extracts and identifed as chlorogenic acid, 3’,4’,5,7-tetrahydroxyfavone; dicaffeoyl quinic acid; 3’,4’,5,7-tetrahydroxy-3,6-dimethoxyfavone; 3’,4’,5,7-tetrahydroxy-3,6,8-trimethoxy favone, 4’,5,7-trihydroxy-3’,3,6,8-tetramethoxyfavone and 4’,5-dihydroxy-3’,3,6,7,8-pentamethoxyfavone. The main constituents from the methanol extract and infusion were caffeic acid derivatives. This is the frst report on the constituents of B. incarum infusion and show clear differences with previous phytochemical studies on the same plant. All isolated compounds showed antioxidant activity with SC50 values of 1 to 10 µg/ml. The isolated favones were active against methicillin-resistant Staphylococcus aureus and Enterococcus faecalis with MICs in the range 100 and >200 µg/ml. <![CDATA[<b>AN EMPIRICAL WAY TO CORRECT SOME DRAWBACKS OF MULLIKEN POPULATION ANALYSIS</b>]]> The problem of negative electronic populations and of occupation numbers greater than 2 has plagued Mulliken Population Analysis since the very beginning. Through the analysis of three model molecular systems, several basis sets and the relevant literature, we conclude that there is not enough evidence to assign the origin of these errors to the self-consistent scheme, to Mulliken’s partition, to the basis set structure or to a combination of these. As Mulliken Population Analysis is still widely used, we have developed an empirical method to eliminate negative electronic populations and occupation numbers greater than 2. This method can be used for any partition of the electron density (not only Mulliken’s), for any basis set and for any LCAO-MO methodology (semiempirical or ab initio). Finally, the method does not produce any change in the original atomic net charges. <![CDATA[<b>CHEMOTAXONOMIC SIGNIFICANCE OF FLAVONOIDS IN THE SOLANUM NIGRUM COMPLEX</b>]]> Five locally available plant taxa of Solanum nigrum Complex were investigated to resolve the International taxonomic controversy about these plants by analyzing their favonoid profles. Total favonoid contents in the taxa were determined by two complementary colorimetric methods, aluminum chloride method and 2,4-dinitrophenylhydrazine method. Thin layer chromatography was used to detect the glycosides of quercetin. Whereas GC-MS analysis of the hydrolyzed extracts showed the relative percentage of quercetin aglycon in the taxa under study. Statistical analyses of the results were employed for grouping of these taxa into various clusters. The signifcant distance found between S. americanum, S. chenopodioides, S. nigrum and S. villosum indicated them as distinct species. But S. retrofexum did not show such a marked difference and hence might be regarded as a variety or subspecies of S. nigrum. <![CDATA[<b>THREE NEW TETRAALKYLAMMONIUM BROMOCHROMATES, NR<sub>4</sub> [CRO<sub>3</sub>BR], (R= ET, HEX, HEP)</b>: <b>MILD AND EFFICIENT REAGENTS FOR OXIDATION OF PRIMARY AND SECONDARY ALCOHOLS</b>]]> Tetraethylammonium Bromochromate, TEABC, Tetrahexylammonium Bromochromate, THexABC and Tetraheptylammonium Bromochromate, THepABC are new reagents used for almost quantitative conversion of alcohols into the corresponding aldehydes and ketones. These tetraalkylammonium bromochromate reagents are easily synthesized by the reaction of relative tetraalkylammonium bromide with a solution of CrO3 in a 1:1 mole ratio. These reagents are versatile agents for the effective and nearly quantitative oxidation of organic substrates, in particular for alcohols, under mild and acid-free conditions.