Scielo RSS <![CDATA[Journal of the Chilean Chemical Society]]> http://www.scielo.cl/rss.php?pid=0717-970720150002&lang=en vol. 60 num. 2 lang. en <![CDATA[SciELO Logo]]> http://www.scielo.cl/img/en/fbpelogp.gif http://www.scielo.cl <![CDATA[<b>HIGH PERFORMANCE LIQUID CHROMATOGRAPHIC METHOD FOR THE QUANTITATIVE ANALYSIS OF CEFUROXIME IN PHARMACEUTICAL PREPARATIONS</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200001&lng=en&nrm=iso&tlng=en New Analytical method has been developed for the determination of Cefuroxime in pharmaceutical formulations. The method involves the application of high performance Liquid chromatography (HPLC) for the quantitative analysis of cefuroxime. HPLC method has a shorter analysis time of 10 min. The developed method obeyed the Beer's law in the range of 5- 300 μg mL-1. Limit of detection (LOD) and limit of quantitation (LOQ) of the developed method was found to be 0.538 and 1.63, μg mL-1 respectively. <![CDATA[<b>SYNTHESIS, STRUCTURES AND ANTIMICROBIAL ACTIVITY OF CHLORO- AND FLUORO-SUBSTITUTED THIOCARBOXYHYDRAZONES</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200002&lng=en&nrm=iso&tlng=en A series of chloro- and fluoro-substituted thiocarboxyhydrazones, 2-(2-chlorobenzylidene)-N-methylhydrazinecarbothioamide (1), 2-(4-fluorobenzylidene)-N-methylhydrazinecarbothioamide (2), and 2-(2-chloro-4-fluorobenzylidene)-N-methylhydrazinecarbothioamide (3), were synthesized and characterized by elemental analysis, IR and UV-vis spectra, and single crystal X-ray diffraction. Structures of the three compounds are similar, but with slight modification by chloro- and fluoro-substitute groups. The crystal structures of the compounds are stabilized by hydrogen bonds and π···π interactions. The antimicrobial activity of the compounds shows that they are effective against some bacteria. <![CDATA[<b>SYNTHESIS AND CHARACTERIZATION OF AMINATED COPOLYMERS OF POLYACRYLONITRILE-GRAFT-CHITOSAN AND THEIR APPLICATION FOR THE REMOVAL OF HEAVY METALS FROM AQUEOUS SOLUTION</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200003&lng=en&nrm=iso&tlng=en Aminated copolymers of polyacrylonitrile-graft-chitosan (APANCS) were synthesized via the reaction of copolymers of polyacrylonitrile-graft-chitosan (PAN-g-CS) with diethylenetriamine in solution. Specifically, copolymers of PAN-g-CS have been obtained via a graft polymerization method using acrylonitrile (AN), chitosan (CS) and a free-radical initiating process with ceric ammonium nitrate (CAN) as initiator under air presence. Superficial structure of these copolymers was modified using amination reactions to introduce amine groups on its polymeric matrix. This polymer (APANCS) was applied in the removal of Pb2+, Cd2+ and Zn2+ ions in aqueous solutions. Samples of PAN-g-CS and APANCS were characterized by FT-IR spectroscopy, scanning electron microscopy/energy-dispersive X-ray spectroscopy, TGA, DSC and gravimetric analyses. Results of this study suggest that the amine groups of the structure of chitosan are involved in the grafting process onto the polymeric matrix of polyacrylonitrile. On the other hand, the adsorption capacities for heavy metal removal of this polymer were significantly improved using the chemical modification with amination reactions. Specifically, this polymeric material showed a maximum adsorption of 12.93, 2.27 and 2.10 mg/g at pH 5 for the removal of Pb2+, Cd2+ and Zn2+ ions, respectively. <![CDATA[<b>THE APPLICATION OF IRON (III) PHOSPHATE IN THE SYNTHESIS OF <i>N</i>-SUBSTITUTED PYRROLES</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200004&lng=en&nrm=iso&tlng=en A variety of N-substituted pyrroles have been prepared by reacting 2,5-hexadione with amines or diamines in the presence of iron (III) phosphate at room temperature under solvent-free conditions. The experiment protocol features simple operations, and the products are isolated in high yields (88-99%). <![CDATA[<b>MICROBIOLOGICAL PRECIPITATION, MORPHOLOGY AND THERMAL BEHAVIOR OF BARIUM HYDROGEN PHOSPHATE</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200005&lng=en&nrm=iso&tlng=en The barium hydrogen phosphate (BHP) precipitate was induced using enzymes in the Bacillus subtilis reproduction and structure, morphology and thermal properties of the barium hydrogen phosphate precipitate were characterized by Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDS), X-ray techniques (XRD), scanning electron microscope (SEM), thermogravimetric-differential scanning calorimetry (TG-DSC) analysis. There is no obvious difference in the composition and structure but the diffraction intensity. Morphology of BHP via microbiological precipitation differs from chemical and biomimetic process, and its brick-like shape is observed. Compared with chemical synthesis, there are bigger total weight-loss (7.47%) and lower decomposition or melting points (355.5°C) of BHP by microbiological precipitation, possibly caused by organic matrices. <![CDATA[<b>SYNTHESIS AND CHARACTERIZATION OF CERIUM FLUORITES BASED ON Ce<sub>1-x</sub>Ln<sub>x</sub>O<sub>2</sub></b><b><sub>-</sub></b><b><sub>δ</sub></b><b> SYSTEM (Ln: Nd<sup>3+</sup>, Sm<sup>3+</sup>, Eu<sup>3+</sup>, Gd<sup>3+</sup>, Dy<sup>3+</sup> AND Ho<sup>3+</sup>)</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200006&lng=en&nrm=iso&tlng=en This paper describes the synthesis of 18 oxides of Ce1-xLn xO2 (Ln: Nd3+, Sm3+, Eu3+, Gd3+, Dy3+ and Ho3+), with x = 0.05, 0.10 and 0.15 mol% by use of a wet chemical route that involving the obtention of coordination compounds type citrate, which allow the generation of a number of chemical and surface properties with potential catalytic applications in solid oxide fuel cells technologies. The materials obtained by this route, has a high purity and homogeneity, enabling calcination temperatures and residence times considerably brief, in comparison with conventional synthetic routes. All oxides, were calcined at 300 °C under flow oxygen and were characterized by X-ray diffraction (XRD), from obtained results, we confirmed the presence of a pure fluorite structure of CeO2 consistent with the ICSD pattern reference of 072155 with space group Fm-3m (225). Subsequent physicochemical characterization by TPR and electron microscopy (SEM-TEM), confirm that cerium oxides could be reduced in two single steps at different temperatures, kinetically detectable and clearly prolonged as well as the obtention of nanostructured solids with a crystallite size between 32-47 nm. According with obtained results, the solids show a high surface area as result of the low calcination temperature. The electrical characterization by impedance spectroscopy (IS), revealed an important concentration of charge carriers in fluorite oxides, mainly in the sample of GDC5, which is a crucial characteristic in advanced materials for SOFC applications. The catalytic studies, conducted on materials at 700 °C under stable reaction conditions, confirm that the methane conversion levels change throughout the series GDC5 → NDC5 → HDC5 → EDC5 → DDC5 → SDC5, which established that the GDC5 solid, exhibits the most promising results. Finally, a stability test was achieved with the GDC5 catalyst under the same reaction conditions established in previous form, for a period of 240 hours of continuous flux, establishing the effectiveness of the proposed method to choice the most promissory material. The results confirmed as the methane conversion vary as function of time and the obtained syngas levels change for potential technological applications. <![CDATA[<b>CYTOTOXIC AND ANTIMICROBIAL ACTIVITIES OF TWO NEW TRITERPENOIDS FROM THE PEELS OF LOCAL EGYPTIAN MALUS DOMESTICA L.</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200007&lng=en&nrm=iso&tlng=en The local Egyptian peels of Malus domestica was extracted successively with absolute ethanol and partitioned sequentially with n-hexane, chloroform and methanol. Friedelin (1) was isolated from the n-hexane fraction, and betulinic acid (2) from the chloroform fraction. The new compounds 2α-hydorxy-3-oxo-lup-12(13), 20(29)-dien-27, 28-dioic acid (3) and 2α, 27-dihydorxy-3-oxo-lup-12(13), 20(29)-dien-28-oic acid (4) were isolated from the methanol fraction and elucidated by spectroscopic data interpretation. Friedelin (1) and betulinic acid (2) are known compounds that are newly identified from peels of Malus domestica. The compounds 3 & 4 are appreciably active against Gram-positive species and Gram-negative species, associated with week anti-fungal activity. Among them, compounds (3) and (4) exhibited cytotoxic activity against the breast carcinoma and human colon carcinoma cells, with (4) being slightly most potent toward to the breast carcinoma while, (3) being slightly most potent toward to the human colon carcinoma cells . <![CDATA[<b>GREEN SYNTHESIS OF 2-AMINO-3-CYANO-4<i>H</i>-CHROMENES IN WATER USING NANO SILICA-BONDED 5-N-PROPYL-OCTAHYDRO-PYRTMIDO[1,2-4]AZEPINIUM CHLORIDE AS AN EFFECTIVE AND REUSABLE NANO CATALYST</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200008&lng=en&nrm=iso&tlng=en Nano silica-bonded 5-n-propyl-octahydro-pyrimido[1,2-a]azepinium chloride (NSB-DBU) is reported as an highly efficient and recyclable nano catalyst for the preparation of 4H-chromene derivatives in aqueous media. This synthetic method offers a simple, mild and time-saving method under entirely green and environmentally friendly conditions. <![CDATA[<b>SELECTIVE CHEMICAL ETCHING FOR STUDYING THE FRONT SIDE CONTACT IN THICK FILM SCREEN PRINTED CRYSTALLINE P-TYPE SILICON SOLAR CELLS</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200009&lng=en&nrm=iso&tlng=en Crystalline silicon solar cells are currently the leading technology in the photovoltaic market with no great expectable change in the shares. The scientific community works on the further development and improvements of state-of-the-art as well as new solar cell materials. This paper reports on a chemical methodology for selective etching to study the metallization step in monocrystalline silicon solar cells. The object of study is a complete processed silicon solar cell which was cleaved via laser beam on the back side and broken per hand to obtain stripes of the size 15.6×1 cm². In the following a sequence of etching chemical solutions to selectively remove the components of the front side silver contact was applied. Scanning electron microscopy was used to investigate contact interface after each etching step. The silver finger, the glass and the silver crystallites grown in silicon could be removed. It came out that the silver crystallites preferably grow at the pyramid tips and edges of the textured wafer. A characterization with Energy Dispersive X-Ray Spectrometry was performed to quantify the components of the silver contact after each chemical etching step. While the weight percentage of silver reduced by more than 90% after an aqua regia treatment, it increased by 13% after hydrofluoric acid. Silver was practically eliminated after a second aqua regia bath. Similarly, the content of glass was also determined. The approach serves for interface investigations in semiconductor technology where screen printing approaches are used for the metallization. <![CDATA[<b>CVD SYNTHESIS OF GRAPHENE FROM ACETYLENE CATALYZED BY A REDUCED CuO THIN FILM DEPOSITED ON SiO<sub>2</sub> SUBSTRATES</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200010&lng=en&nrm=iso&tlng=en Few-layer graphene was grown by Chemical Vapor Deposition on a CuO thin film pre-deposited by sputtering on SiO2/Si substrates using acetylene as the carbon source. After evaporation of metal, graphene lies directly in contact with the SiO2 dielectric layer. Raman spectroscopy was used to confirm the presence of a single and/or few-layers of graphene. This procedure does not requiring any post processing to transfer the thin film onto a dielectric substrate or the use of ultra-high vacuum during synthesis. <![CDATA[<b>FACILE ONE-POT SYNTHESIS OF SPIROACENAPHTHYLENE DERIVATIVES USING SBA-Pr-NH<sub>2</sub></b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200011&lng=en&nrm=iso&tlng=en A simple procedure afforded novel spiroacenaphthylene derivatives in high yields at room temperature from acenaphthenequinone, malononitrile, and phenol derivatives using amino-functionalized silica (SBA-Pr-NH2) as a heterogeneous efficient solid base catalyst. Using SBA-Pr-NH2 in the current procedure presents several advantages, such as a simpler procedure, shorter reaction times, facile synthesis, and simpler work-up. Also, recycling of the catalyst was completed with no significant decrease in the activity of catalyst. <![CDATA[<b>SYNTHESIS AND ANTIOXIDANT EVALUATION OF NOVEL PHENOTHIAZINE LINKED SUBSTITUTEDBENZYLIDENEAMINO-1,2,4-TRIAZOLE DERIVATIVES</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200012&lng=en&nrm=iso&tlng=en A series of novel 5-((10H-phenothiazin-10yl)methyl)-4-(substitutedbenzylideneamino)-4H-1,2,4-triazole-3-thiol derivatives (6a-i) have been synthesized from compound (1) through a multi-step reaction. The key intermediate (5) afforded a series of title compounds (6a-i) on condensation with various suitable aldehydes in the presence of H2SO4. The structures of novel compounds were characterized based on their elemental analysis, IR, ¹H-NMR, 13C-NMR and MS spectral data. All these novel compounds were screened for their in vitro antioxidant activity by employing nitric oxide, hydrogen peroxide, and DPPH radical scavenging assays. The compounds 6d, 6e and 6i demonstrated potent antioxidant activity as these contain the electron-releasing groups. <![CDATA[<b>SYNTHESIS, STRUCTURE, THERMAL STABILITY AND FLUORESCENCE OF A NEW CADMIUM(II) COORDINATION POLYERS AS PRECURSOR FOR PREPARATION OF CdO MICRO-CRYSTAL</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200013&lng=en&nrm=iso&tlng=en A new complex [Cd(btca)0.5(H2O)3] (1) (H4btca: 1,2,4,5-benzenetetracarboxlyic acid) has been synthesized and characterized by single crystal X-ray diffraction studies, elemental analysis and FT-IR. In compound 1, Cd(II) center atoms coordinate to three ligand btca4- anions and three water molecules with a six-coordinated distorted octahedral geometry. Four carboxyl groups of btca4- adopt μ2-η2:η0 and μ1-η1:η0 two different coordination modes. The whole anion btca4- acts as a hexadentate bridge to connect adjacent Cd(II) atoms, resulting in 2D layer structure. Further, these two-dimensional layers are linked together by O-H···O to give rise to three-dimensional structure. Thermal stability and luminescent property of 1 are investigated. CdO micro-crystalline particles are then produced by calcination of compound 1 at 580 ºC. The obtained CdO is characterized by XRD and SEM analyses. <![CDATA[<b>UNIFIED TREATMENT OF ONE- AND TWO-CENTER ONE-RANGE ADDITION THEOREMS FOR COMPLETE ORTHONORMAL SETS OF SELF-FRICTIONAL EXPONENTIAL TYPE ORBITALS AND NONINTEGER <i>n</i> SLATER FUNCTIONS</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200014&lng=en&nrm=iso&tlng=en Using L(α*) -self-frictional Laguerre polynomials (L(α*) -SFLPs) introduced by the author in standard convention, the combined theory of one- and two-center one-range addition theorems for complete orthonormal sets of ψ(α*) -self-frictional exponential type orbitals (ψ(α*) -SFETOs) and χ -noninteger n Slater type orbitals ( -NISTOs) in terms of χ -integer n STOs (χ -ISTOs) is established, where α* are the integer (α* = α, −∞ < α ≤ 2) or noninteger (α* ≠ α, −∞ < α < 3) SF quantum numbers. The expansion coefficients of these one-range addition theorems are expressed through the overlap integrals of χ -NISTOs. <![CDATA[<b>TUNGSTEN AND RHENIUM AS HYDROGENATION AGENTS IN THE HYDRODENITROGENATION OF PYRIDINE USING STACKED BED CATALYST SYSTEMS</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200015&lng=en&nrm=iso&tlng=en This study analyses the hydrodenitrogenation (HDN) of pyridine using a stacked bed catalyst system, composed of a first hydrogenating bed of Re/γ-Al2O3 or W/γ-Al2O3, over a second bed of Ni-Re/γ-Al2O3 (HDN bed). Using potentiometric methods, it can be seen that the Re/γ-Al2O3 shows higher acidic strength than the W/γ-Al2O3. The results show that higher activity levels are obtained working with stacked bed systems compared to the separate catalysts. These results suggest that the incorporation of the catalyst Re/γ-Al2O3 or W/γ-Al2O3 beds would favour the formation of hydrogenated intermediary products, facilitating the removal of N-containing molecules via HDN on the Ni-Re/γ-Al2O3 catalyst. <![CDATA[<b>PROTECTIVE EFFECT OF <i>PHILESIA MAGELLANICA</i> (COICOPIHUE) FROM CHILEAN PATAGONIA AGAINST OXIDATIVE DAMAGE</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200016&lng=en&nrm=iso&tlng=en Philesia magellanica (P. magellanica) is a plant collected in the Chilean Patagonia. Its antioxidant properties were assessed in human erythrocytes exposed in vitro to oxidative stress induced by HClO. Scanning electron microscopy (SEM) observations showed that HClO induced a morphological alteration in the red blood cells from a normal discoid to a spherocytic form, and cells of unequal size. However, a concentration as low as 1 μM gallic acid equivalents (GAE) of P. magellanica aqueous extract neutralized the change effects of 50 μΜ HClO. On the other hand, 20 μΜ (GAE) of the extract considerably reduced the deleterious capacity of 0.25 mM HClO to induce hemolysis in red blood cells. In addition, X-ray diffraction experiments were performed in molecular models of the human erythrocyte membrane. These consisted in multilayers of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), classes of lipids preferentially located in the outer and inner monolayers, respectively of the human erythrocyte membrane. It was observed that P. magellanica only interacted with DMPC affecting its multilayer structure. It was also observed that 0.1 μM (GAE) of P. magellanica neutralized the structural perturbation induced by 0.05 and 0.5 mM HClO. These experiments confirmed the antioxidant properties of P. magellanica aqueous extracts. <![CDATA[<b>ELECTRODEPOSITION OF ZnO NANOROD ARRAYS FOR APPLICATION IN PEROVSKITE BASED SOLAR CELLS</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200017&lng=en&nrm=iso&tlng=en We report a low-cost, free-hole conductor methylammonium lead iodide CH3NH3PbI3 (perovskite)/ZnO nanorods (NR) heterojunction solar cell. ZnO nanorod arrays were obtained electrochemically onto transparent conducting oxide (fluor doped tin oxide, FTO) from an aqueous solution of zinc acetate. The ZnO NR were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and optical transmittance. Solar cell was fabricated forming the perovskite material onto the ZnO thin film. Spin coating of an equimolar mixture of CH3NH3I and PbI2 in γ-butyrolactone solution (perovskite precursor solution) leads to CH3NH3PbI3 formation on ZnO NR. A graphite-covered FTO/glass was used as a back contact. The photovoltaic performance of the solar cell was characterized at full sun intensity of 100 mW/cm² obtaining a shortcircuit current of 1.5 mA/cm², an open circuit voltage of 0.47 V and energy conversion efficiency of 0.16 %. <![CDATA[<b>RAMAN AND SURFACE ENHANCED RAMAN SIGNALS OF THE SENSOR 1-(4-MERCAPTOPHENYL)-2,4,6-TRIPHENYLPYRIDINIUM PERCHLORATE</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200018&lng=en&nrm=iso&tlng=en The sensor 1-(4-mercaptophenyl)-2,4,6-triphenylpyridinium Perchlorate compound was vibrationally characterized using Raman and the Surface-Enhanced Raman techniques, SERS and Shell-Isolated Nanoparticles-Enhanced Raman Spectroscopy (SHINERS). The Raman spectrum was analyzed and the band assignment was supported using DFT data at the B3LYP/6-31G(d) level. SERS data allowed infer about the orientation of the analyte on the naked Ag surface. EHT calculations for an Ag/analyte model represent well the SERS spectrum supporting the Ag-S bond formation. The SHINERS spectrum was obtained by using Ag@SiO2 nanoparticles prepared at two different time of the SiO2 coating process. The most intense SHINERS spectral signals of the compound (100 nM) were obtained after 20 minutes of the Ag@SiO2 formation. No charge-transfer was concluded from the SHINERS experiments. <![CDATA[<b>ESCALATING APPLICATIONS OF HALLOYSITE NANOTUBES</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200019&lng=en&nrm=iso&tlng=en In nanotechnology different nano materials are used like carbon nanotubes, nanofluids, nanoparticles, nanoemulsions, nanocapsules, etc. Due to their toxic effects the results of these nano materials are not considered safe for humans and for the environment as well. Halloysite nanotubules (HNTs) having low cost are naturally occurring environmental friendly nanotubules. These are distinctive and handy materials formed by face weathering of aluminosilicate minerals having definite ratio of aluminum, silicon, hydrogen, and oxygen. HNTs have high mechanical strength and modulus. Due to these properties it is ideal for various applications; remediation of ecological contaminants, these are acting as a career for the delivery of drugs and various macro molecules, storage of H2 gas, for catalytic conversions and for the processing of hydrocarbons. These are also used in anticancer therapy, sustained delivery for certain agents, as a template or nanoreactor for biocatalyst, in personal care, cosmetics and as environment caring. They are also used in the fabrication of high quality white-ware ceramics, nanotemplates and nano scale reaction bottles. Due to easy dispersability in polymer matrix, abundant availability and biocompatibility, HNTs are also used in different epoxy (EP) composites. In this review, we have tried to recap the different aspects of halloysites nanotubes for their use in different research fields. <![CDATA[<b>STRUCTURAL CHARACTERISTICS AND DISTRIBUTION OF LIGNIN IN EUCALYPTUS GLOBULUS PULPS OBTAINED BY A COMBINED AUTOHYDROLSIS/ALKALINE EXTRACTION PROCESS FOR ENZYMATIC SACCHARIFICATION OF CELLULOSE</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200020&lng=en&nrm=iso&tlng=en Eucalyptus globulus wood chips were subjected to autohydrolysis pretreatment at 175°C at three different residence times. Part of the recovered solids were submitted to alkaline extraction with NaOH solution to remove leachable lignin. The chemical composition of the fibrous material was analyzed by HPLC, Py-GCMS and 2D-NMR HSQC, while morphological changes were evaluated by SEM and LSCM. The pretreated materials were hydrolyzed with cellulases at a substrate loading of 10% (w/v) for up to 72 h. Glucose yields (based on dry wood) obtained in the enzymatic hydrolysis ranged between 38% and 65%, depending on reaction time in the autohydrolysis pretreatment. After the alkaline extraction, no significant change was observed in the yields in the enzymatic hydrolysis at 72 h, but at the lower severities, the initial rates of saccharification increased. The main effect of the hydrothermal pretreatment was removal of hemicelluloses, resulting in enriched cellulose pulps. SEM and LSCM images of the hydrothermal pretreated samples showed a disruption of the fiber surface, mainly in those samples obtained at the higher severity. Py-GC/MS and HSQC analysis showed that no major changes in the lignin structure occurred in the samples obtained by autohydrolysis and further alkaline extraction. By autohydrolysis at the higher severity (So=4.02), the lateral chains in lignin were cleaved and the formation of lignin droplets was observed. Hemicelluloses removal and lignin redeposition as droplets in certain regions of the fiber surface was associated with the higher accessibility of cellulose and the yield increase of the enzymatic hydrolysis. <![CDATA[<b>SYNTHESIS, CRYSTAL STRUCTURES, AND ANTIBACTERIAL ACTIVITY OF A SERIES OF HYDRAZONE COMPOUNDS DERIVED FROM 4-METHYLBENZOHYDRAZIDE</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200021&lng=en&nrm=iso&tlng=en A series of hydrazone compounds, 4-methyl-N'-(4-nitrobenzylidene)benzohydrazide methanol solvate (1), N'-(4-hydroxy-3-nitrobenzylidene)-4-methylbenzohydrazide dimethanol solvate (2), and N'-(3,5-dibromobenzylidene)-4-methylbenzohydrazide (3), derived from 4-methylbenzohydrazide with different benzaldehydes, were synthesized and characterized by physico-chemical methods and single crystal X-ray diffraction. Crystals of the compounds are stabilized by intermolecular hydrogen bonds, as well as π···π stacking interactions. Antibacterial activity of the compounds against Staphylococcus aureus, Escherichia coli, and Klebsielle pneumoniae strains was studied. Compounds 1 and 2 have moderate minimum inhibition concentration values on the tested bacteria strains. Compound 3, with the Br-substituent groups, showed the highest activity on the bacterial strains. <![CDATA[<b>THE TAUTOMERISM OF PYRAZOLINES (DIHYDROPYRAZOLES)</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200022&lng=en&nrm=iso&tlng=en The exception to the rule that Δ3-pyrazolines are not stable unless both nitrogen atoms are substituted that has been recently published, Tetrahedron Lett. 55, 2208, (2014), has been proved false. By means of GIAO/B3LYP/6-311++G(d,p) calculations, it has been shown that the product is a pyrazole formed by rearrangement. <![CDATA[<b>SYNTHESIS, CHARACTERIZATION OF A NOVEL CONJUGATED STRUCTURAL OLIGOMER</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200023&lng=en&nrm=iso&tlng=en An octupolar star-shaped ladder-type oligomer composed of electron deriving from 1,3,5-triazine core end-capped by either an electron donating carbazolemoiety (TA(TL)-Ph(3)-CBZ) have been designed and synthesized to investigate the structure-properties relationship of highly efficient multiphoton absorbing materials. The newly synthesized molecules were characterized by ¹H NMR, 13C NMR and mass spectrometry. Linear optical properties of the oligomer were investigated by UV-vis and fluorescence spectrometries, as well as the nonlinear optical properties were characterized by two-photon excited fluorescence (2PEF) measurement. <![CDATA[<b>APPLICATION OF SBA-15 FUNCTIONALIZED SULFONIC ACID (SBA-Pr-SO<sub>3</sub>H) AS AN EFFICIENT NANOREACTOR IN THE ONE-POT SYNTHESIS OF PYRIDO[2,3-<i>d</i>]PYRIMIDINE</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200024&lng=en&nrm=iso&tlng=en Sulfonic acid functionalized nanoporous silica (SBA-Pr-SO3H) with a pore size of 6 nm was synthesized using surface modification of Santa Barbara Amorphous (SBA-15). It is a solid acid hexagonally nano-reactor with high surface area and is reusable, high selective, non-corrosiveness which can easily isolate from the products. An efficient and green one-pot three component reaction was developed for the synthesis of pyrido[2,3-d]pyrimidine derivatives via a simple, mild and effective solvent free reaction of 4(6)-aminouracil, barbituric acid and aromatic aldehydes in the presence using SBA-Pr-SO3H. In this reaction, SBA-Pr-SO3H was an effective nano-catalyst which gave the products in good to high yields in a shorter reaction time compared to the other published reports. Some of the products were strong antibiotics against Bacillus subtilis and Staphylococcus aureus. <![CDATA[<b>ANTIMUTAGENIC AND ANTIOXIDANT POTENTIAL OF AQUEOUS AND ACIDIFIED METHANOL EXTRACTS FROM <i>CITRUS LIMONUM</i> FRUIT RESIDUES</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200025&lng=en&nrm=iso&tlng=en Aqueous and acidified methanol extracts from C. limonum fruit residues (CLFR) were evaluated for their total phenolic contents, antioxidant and antimutagenic activities. Total phenolic contents (TPC) of aqueous (30% and 70%) and acidified (0.5 N and 1.0 N) methanol extracts from CLFR were estimated by Folin-Ciocalteu reagent method whereas in-vitro antioxidant activity was assessed calorimetrically by measuring DPPH* scavenging capacity and inhibition of linoleic acid peroxidation. Anti-mutagenic potential of the extracts was appraised by Ames bacterial reverse mutation test. TPC, DPPH° scavenging capacity and inhibition of linoleic acid peroxidation were varied from 27.75-126.35 mg gallic acid equivalent (GAE)/g DW, 46-91%, and 34-83%, respectively. All the tested extracts of CLFR noticeably hunted mutagens (16.47-55.69 %) whereas none of these caused mutagenesis. Overall, acidified methanol extracts from CLFR exhibited higher extraction yields, TPC, inhibition of peroxidation and DPPH radical scavenging activity among others indicating a significant (p<0.05) variation of these attributes in relation to residue samples and extraction media. The results support that CLFR (peel and pulp biomass) being a rich source of phenolic antimutagens, can be explored as a potential candidate for the development of natural chemo-preventive drugs and nutracueticals. <![CDATA[<b>ERRATUM</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072015000200026&lng=en&nrm=iso&tlng=en Aqueous and acidified methanol extracts from C. limonum fruit residues (CLFR) were evaluated for their total phenolic contents, antioxidant and antimutagenic activities. Total phenolic contents (TPC) of aqueous (30% and 70%) and acidified (0.5 N and 1.0 N) methanol extracts from CLFR were estimated by Folin-Ciocalteu reagent method whereas in-vitro antioxidant activity was assessed calorimetrically by measuring DPPH* scavenging capacity and inhibition of linoleic acid peroxidation. Anti-mutagenic potential of the extracts was appraised by Ames bacterial reverse mutation test. TPC, DPPH° scavenging capacity and inhibition of linoleic acid peroxidation were varied from 27.75-126.35 mg gallic acid equivalent (GAE)/g DW, 46-91%, and 34-83%, respectively. All the tested extracts of CLFR noticeably hunted mutagens (16.47-55.69 %) whereas none of these caused mutagenesis. Overall, acidified methanol extracts from CLFR exhibited higher extraction yields, TPC, inhibition of peroxidation and DPPH radical scavenging activity among others indicating a significant (p<0.05) variation of these attributes in relation to residue samples and extraction media. The results support that CLFR (peel and pulp biomass) being a rich source of phenolic antimutagens, can be explored as a potential candidate for the development of natural chemo-preventive drugs and nutracueticals.