Scielo RSS <![CDATA[Journal of the Chilean Chemical Society]]> vol. 51 num. 3 lang. es <![CDATA[SciELO Logo]]> <![CDATA[<i>N</i>-SUBSTITUTION AND <strong>á</strong><strong><sub>1</sub></strong><strong>-ADRENERGIC RECEPTOR AFFINITY OF LAUDANOSINE ANALOGUES</strong>]]> Benzyltetrahydroisoquinoline (BTHIQ) molecules are able to adopt widely differing conformations that depend on the presence or absence of N-substituents. To assess the possible role of BTHIQ conformation on the affinity of these compounds for a 1-adrenergic receptors, of interest for the management of hypertension, the racemic N-unsubstituted BTHIQ norlaudanosine and a series of N-alkylated derivatives were assessed for binding to rat brain cortical sites labelled with the radioligand [³H]prazosin. The a 1-adrenergic affinity in this series increased with the bulk of the substituent on the nitrogen atom, from the N-ethyl to the N-propyl analogue. Comparison of these results with published data for related BTHIQs and for the rigid mimics of the fully extended and semi-folded conformations of laudanosine, tetrahydropalmatine and glaucine, suggested that the a 1-adrenergic receptor binding site is able to accommodate either conformation. The presence of a bulky substituent on the nitrogen atom seems to favor receptor binding independently of the favored conformation, and that the orientation in which BTHIQs are bound probably differs depending on the presence or absence of a hydroxyl group at a key position <![CDATA[HYDROCARBONS AND ORGANOCHLORINE PESTICIDES IN SOILS OF THE URBAN ECOSYSTEM OF CHILLÁN AND CHILLÁN VIEJO, CHILE]]> Although traditional soil use in Chillán and Chillán Viejo is agricultural, both cities have seen their surrounding areas expand and change drastically. Economic activities have increased, including phytosanitary companies and petroleum derivatives used in agriculture and transport. This has had a large impact on the soil. The present work studies total hydrocarbon contamination (lineal and polycyclic aromatics) and chlorine pesticides (Aldrin, Dieldrin, DDT, and DDE) in surface soils near potential sources of pollution. The concentration of total hydrocarbons in the majority of the samples analyzed is between 0.1 and 70 mg/kg. Only 8.8 % exceed 70 mg/kg., indicating the need for recovery before use, according international regulations. The pesticide Aldrin was found in 41.2 % of the soil samples, DDT in 32.4 %, Dieldrin in 29.4%, and DDE in 2.9%. These levels exceed the maximum limits established for ecological improvement in Chile. Amongst themselves, total hydrocarbons correlated with total pesticides and with DDT, but not with Aldrin or Dieldrin. Correlations were also found for total pesticides with DDT and Aldrin, and strong correlations were observed for DDT with Aldrin, and Aldrin with Dieldrin <![CDATA[<strong>BLENDS OF POLY(METHYL METHACRYLATE-CO-METHACRYLIC ACID) AND TWO DIHYDRIC PHENOLS</strong>: <strong>THERMAL AND INFRARED SPECTROSCOPIC STUDIES</strong>]]> The miscibility in blends containing poly(methyl methacrylate-co-methacrylic acid) [P(MMA-co-MA)] as polymer component and the dihydric phenols 4,4'-thiodiphenol (TDP) and 4,4'-methyllendiphenol (MDP) as low molecular weight compounds (LMWC) was studied by Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectrophotometry (FTIR). Thermal properties, such as the glass transition of P(MMA-co-MA) and the melting of the LMWC, were found to be clearly affected when the compounds were blended, which was attributed to the miscibility between them. FTIR was used to investigate the specific interactions between P(MMA-co-MA) and the LMWC. The formation of intermolecular hydrogen bonds between the carbonyl groups of P(MMA-co-MA) and the hydroxyl groups of TDP and MDP were discovered. Thermogravimetric and viscometry analysis were also used as additional techniques to complement the obtained FTIR and DCS results <![CDATA[<strong>PHOTOCHEMICAL DEPOSITION OF Pd-LOADED AND Pt-LOADED TIN OXIDE THIN FILMS</strong>]]> Pd and Pt loaded tin OXide thin films have been successfully prepared by direct UV irradiation of amorphous films of ß-diketonate complexes on Si(100) substrates. Tin OXide films loaded with 10, 30 and 50% Pd and Pt, were characterized by Auger electron spectroscopy (AES). The Auger peak intensity ratios of O KL23L23 to Sn M4N45N45 showed that as-deposited films consist of mixed tin OXide phases whereas annealed films consist mainly of single phase SnO2. The results showed that the stoichiometry of the resulting films is in relative agreement with the composition of the precursor films. The surface characterization of these thin films was performed using Atomic Force Microscopy (AFM). This analysis revealed that loaded tin OXide films have a much rougher surface than unloaded films, with rms roughness values ranging from 28-54 nm for as-deposited Pd-SnO X films to 3.6-20 nm for as-deposited Pt-SnO X films. It was also found that Pt-loaded tin OXide films present a better particle size distribution and uniformity when compared to Pd-loaded tin OXide films. These results demonstrate the potential use of these deposited films in the manufacture of gas-sensing devices <![CDATA[<strong>MAGNETIC PROPERTIES AND ANTIBACTERIAL ACTIVITY OF TETRANUCLEAR COPPER COMPLEXES BRIDGED BY OXO GROUP</strong>]]> A series of three tetranuclear Cu(II) complexes of general formula [Cu4OCl6L4], where L is a Lewis Base ligand has been characterized through magnetic measurements and determination of antimicrobial activities. This study include the following species [Cu4OCl6)Cl(PhIm)3](HPhIm)•H2O (1) where PhIm= 4-phenylimidazole, [(Cu4OCl6)(PyNO)4]•1/5(H2O) (2) where PyNO= Pyridine-N-oxide and [(Cu4OCl6)(MeIm)4]•3(CH3OH) (3) where MeIm = 2-methylimidazole. The polynuclear cluster in the complexes contains a central oxygen atom tetrahedral coordinated to four copper(II) ions, each of which coordinates a monodentate L ligand. Each pair of copper atoms is bridged by on a chlorine ion, resulting a trigonal bipiramidal environment. The variable temperature magnetic susceptibilities of these complexes were investigated in the temperature range 5-300K. Satisfactory fits to the observed susceptibility data were obtained only for the complexes (1) and (3), by assuming isotropic magnetic exchange interactions and using the appropriate spin Hamiltonian and susceptibility equation giving the coupling constants J1= 0.148cm-1, J2= -1.707 cm-1 for (1) and J1= 0.522 cm-1, J2= -5.32 cm-1 for (3). The antimicrobial activities of these complexes have been screened in vitro against Gram positive and negative bacteria <![CDATA[<strong>SYNTHESIS AND RESOLUTION OF THE OPTICAL ISOMERS OF THIENCYNONATE HYDROCHLORIDE</strong>]]> Thiencynonate hydrochloride (N-methyL-9á-(3-azabicyclo[3,3,1]nonanyl)-2'-cyclopentyL-2'- hydroxyL-2'-thienylacetate, I·HCl), an new muscarinic receptor antagonist, was synthesized and its enantiomers were obtained form the optical pure of demethylation product II. A convenient resolution method of demethylation product II has been developed with N-p- toluenesulfonylglutamic acid as the resolution reagent. The structures of I and II were elucidated by X-ray analysis <![CDATA[<strong>DETERMINATION OF NINE COMPONENTS IN BAYER LIQUORS BY HIGH PERFORMANCE ION CHROMATOGRAPHY WITH CONDUCTIVITY DETECTOR</strong>]]> A High Performance Ion Chromatographic (HPIC) method for the determination of nine components in Bayer liquors was reported. Formic, acetic, propionic, oxalic, succinic, glutaric anion, F-, Cl-, and SO4(2-) were separated and determined by High Performance Ion Chromatography with conductivity detector. The analytes were removed from Bayer liquor by using an ion-exchange resin column. The chromatographic separation was achieved with only one IonPac AS11-HC column thermostated at 30 °C. The precision results showed that the repeatability and reproducibility were <2.94 and <1.37%, respectively. The accuracy of the method was assessed by the recoveries ranging from 86.3 to 105.6 %. Under optimum conditions the detection limits ranged from 0.008 to 0.053 mg/l <![CDATA[<strong>PI INDEX OF SOME BENZENOID GRAPHS</strong>]]> The Padmakar-Ivan (PI) index of a graph G is defined as PI(G) = ∑[neu(e|G)+ n ev(e|G)], where neu(e|G) is the number of edges of G lying closer to u than to v, n ev(e|G) is the number of edges of G lying closer to v than to u and summation goes over all edges of G. In this paper, we first compute the PI index of a class of pericondensed benzenoid graphs consisting of n rows, n ≤ 3, of hexagons of various lengths. Finally, we prove that for any connected graph G with exactly m edges, PI(G) ≤ m(m-1) with equality if and only if G is an acyclic graph or a cycle of odd length <![CDATA[<strong>STUDY OF POLYPYRROLE FILMS MODIFIED WITH COPPER AND SILVER MICROPARTICLES BY ELECTROCHEMICAL CEMENTATION PROCESS</strong>]]> Electroactive polypyrrole (PPy) films obtained under potentiostatic electropolimerization from aqueous solutions of pyrrole doped with sulfate (SO4(2-)) anions were modified by incorporation of copper (Cu) and silver (Ag) microparticles using electrochemical cementation process. The electrochemically deposited and dissolving processes metals (Cu and Ag) onto and from polypyrrole were investigated. The PPy-Cu and PPy-Ag electrodes were characterized by electrochemical techniques and scanning electron microscopy (SEM) analysis and the electrochemical response of these modified electrodes was compared to that of the unmodified polypyrrole electrode. The results indicate that two forms of metal, valence and elemental ones, can be formed on polypyrrole at a constant cathodic potential. However, only the valence metal can be left on polypyrrole at the anodic potential. The copper and silver particles interact with polypyrrole films involving a strong complex formation affecting its electrochemical behavior. Scanning electron microscopy measurements show that dendritic-like metal aggregates are formed on the film surface. The electrochemical experiments reveal that metal deposition on conducting polymer can be envisaged as an attractive method for the electrodes fabrication <![CDATA[<strong>PREPARATION AND STUDY OF A 1-FUROYL-3,3-DIETHYLTHIOUREA ELECTRODE</strong>]]> Cadmium (II) electrode based on plasticized PVC membranes with 1-furoyl-3,3-diethyl thiourea as ionophore and tributylphosphate as plasticizer has been developed. The membrane was applied on a support of conducting epoxy resin. Some parameters of evaluation of the electrode are presented in this work. The constructed electrode showed linear response in the concentration range of 10-6 -10-3 mol/dm³, had a slope of 28.5 mV/decade, a detection limit (DL) of 2.10-6 mol/dm³ and a lower limit of lineal range (LLLR) of 4.2.10-6 mol/dm³. The static response time obtained was less than 20 seconds. The Cd/S relationship in the membrane was 1:1, as was determined by chemical microanalysis of energy dispersive X-ray spectroscopy (EDS). The constructed electrodes had a life-time of 5 days <![CDATA[<strong>THE PREPARATION OF OXYGENATED DERIVATIVES OF AMBROX AND ISOAMBROX FROM DRIMENOL</strong>]]> The preparation of oxygenated derivatives of ambrox and isoambrox is described. The compounds 8á-hydroxy-isoambrox, 7β-hydroxy-isoambrox, 8á-hydroxy-ambrox, 7β-hydroxy-ambrox, 7-oxo-isoambrox and 7-oxo-ambrox have been synthesized from (-)-drimenol, readily available from the bark of Drimys winteri. The structures of the products were determined mainly by spectroscopic methods <![CDATA[<strong>SYNTHESIS AND CHARACTERIZATION OF 4-ARYLAMINOBIPHENYLGLYOXIMES AND THEIR COMPLEXES</strong>]]> 4-Chloroacetylbiphenyl has been synthesized by Friedel-Crafts reaction between biphenyl and chloroacetyl chloride in the presence of AlCl3 catalyst. The nitrosation reaction of this compound gave 4-biphenylhydroxamyl chloride (HL). Subsequently, 4-biphenylchloroglyoxime (H2L) was prepared by the reaction of 4-biphenylhydroxamyl chloride and hydroxylamine hydrochloride. Then, six new substituted 4-biphenylaminoglyoximes (H2Lx) have been synthesized from 4-biphenylchloroglyoxime and the corresponding amines. A series of M(II)-dioxime complexes of the type [M(HLx)2] or [M(HLx)2(H2O)2] [M(II)=Co(II), Ni(II), Cu(II)] have been synthesized and characterized by FT-IR, ¹H NMR spectral studies, elemental analysis, AAS and magnetic susceptibility measurements <![CDATA[<strong>A HIGH YIELD SYNTHESIS OF 1,2:5,6-DI-O-ISOPROPYLIDENE-D-MANNITOL</strong>]]> A HIGH YIELD SYNTHESIS OF 1,2:5,6-DI-O-ISOPROPYLIDENE-D-MANNITOL: A great improvement in the synthesis of 1,2:5,6-di-O-isopropylidene-D-mannitol (2) using D-mannitol (1) as starting material, is described. The acetalation of (1) was performed in acetone in the presence of zinc chloride as catalyst to give (2) in 87% yield. Some studies on the acetal stability were carried out to explain the high yields. High field NMR spectra were obtained and assignment of all signals was accomplished with the aid of double irradiation, difference NOE and HETCOR spectra <![CDATA[<strong>SYNTHESIS AND CHARACTERIZATION OF GADOLINIUM COLLOIDS IN 2-METHOXYETHANOL</strong>]]> Gadolinium colloids have been prepared by Chemical Liquid Deposition (CLD). The metal is cocondensed with 2-methoxyethanol to yield solvated metal atoms at liquid nitrogen temperature and upon warming stable liquid colloids are formed with several ranges of particle size depending on the amount of metal used. Zeta potentials (ξ) were calculated according to the convention of Hunter and the Hückel equation, for most of these negatively charged particles. Upon solvent removal, colloidal particles coalesce to form active solids, which contain some residual solvent. The synthesis of colloids and active solids from Gd with 2-methoxyethanol is reported. Transmission Electron Microscopy (TEM) allows us to determine particle size ranging from 20 to 30 nm.. The UV-vis studies of the metal colloids reveals absorption bands at 241 and 298 nm. This studies indicate that organic solvents are solvating metal clusters <![CDATA[<strong>THE EFFECT OF PHYSICAL AND CHEMICAL PARAMETERS ON THE STRUCTURE AND COMPOSITION OF THE PHYTOPLANKTON COMMUNITY OF LAKE BUDI (IX REGION, CHILE)</strong>]]> The chemical characteristics of the waters of Lake Budi (IX Region, Chile), in winter and summer were analysed in order to establish seasonal variations and determine their influence on the various phytoplankton components. On the basis of the results it was possible to indicate that the chemical parameters found in the water body under examination vary in time and space, giving rise to different algal communities. The strong influence of salinity on the phytoplankton communities in both study periods appears to result principally from the influence of the sea, resulting from the intrusion of salt water during certain periods of the year. The predominant chemical characteristic in summer indicates a slight reduction in water quality, due to a rise in temperature and a reduction in the oxygen concentration