Scielo RSS <![CDATA[Journal of the Chilean Chemical Society]]> vol. 59 num. 3 lang. es <![CDATA[SciELO Logo]]> <![CDATA[<b>DEVELOPMENT OF A NEW ANALYTICAL METHODOLOGY BASED ON THE CATALYTIC EFFECT OF AG(I) IN A NEW FUCHSIN-PEROXODISULFATE-1,10-PHENANTROLINE SYSTEM</b>: <b>APPLICATION TO THE DETERMINATION OF TRACE AMOUNTS OF SILVER</b>]]> A simple, rapid and sensitive kinetic spectrophotometric method is proposed for the determination of trace amounts of silver ion in the concentration ranges of 2-20 and 20-50 μg L-1. The proposed method is based on the catalytic effect of Ag(I) on the oxidation reaction of new fuchsin by potassium peroxodisulfate in the presence of 1,10-phenantroline as an activator at pH:5.0. The reaction is followed spectrophotometrically by measuring the change in absorbance at 547 nm using the initial rate method during the indicator reaction of 5 minute. The reaction rate variables like pH, reagent and activator concentrations and effect of reaction time and temperature were optimized in order to achieve the maximum analytical sensitivity. The experimental and theoretical detection limits of the developed method were found as 0.475 μg L-1 and 1.50 μg L-1, respectively. The relative standard deviations for five replicate measurements of 15 and 35 μg L-1 of Ag(I) were 5.27% and 3.32%, respectively. The effect of different diverse ions on the determination of silver was studied and found to be free from most interference. The method was successfully applied to the determination of silver in photographic solutions and different real water samples such as tap water, pond water and natural spring waters. <![CDATA[<b>SYNTHESIS OF STEROIDAL DIAZOLIDINONE, DIAZOLIDINTHIONE AND DIAZOLES</b>: <b>REACTION OF STEROIDAL DIBROMOKETONES WITH NUCLEOPHILIC NITROGEN</b>]]> Reaction of 5,6β-dibromo-5α-cholestan-3-one 1 with thiourea, urea and guanidine hydrochloride provided 3-hydroxycholest-3-eno [5α,6α-d] 1',3'-diazolidin-2'-thione 2, 3-hydroxycholest-3-eno [5α,6α-d] 1',3'-diazolidin-2'-one 3 and 3-hydroxycholest-3-eno [5α,6α-d] 2'-amino-1',3'-diazole 4 respectively. The structures of these products have been established on the basis of their elemental analysis and spectral data (IR, ¹H NMR and MASS). <![CDATA[<b>MONO-, TRINUCLEAR NICKEL(II) AND COPPER(II) DIOXIME COMPLEXES</b>: <b>SYNTHESIS, CHARACTERIZATION, CATECHOLASE AND CATALASE-LIKE ACTIVITIES, DNA CLEAVAGE STUDIES</b>]]> The synthesis and molecular structures of six new mono- and trinuclear complexes [M¹L2(M²{Phen)}2J(ClO4)2 [phen = 1,10-phenanthroline, H2L = dioxime ligand, M¹, M² =Ni(II) and Cu(II)] of the ligand, 4-(4-methylphenylamino) biphenylglyoxime are reported. Structural assignments are supported by a combination of FT-IR, elemental analyses, ICP-OES, magnetic susceptibility and molar conductivity studies. Furthermore these complexes were each tested for their ability to catalyze the oxidation of catechol substrates to quinone with dioxygen at 25ºC and disproportionation of hydrogen peroxide in the presence of the added base imidazole. The catalytic results indicated that the heterotrinuclear Cu(II)Ni(II)Cu(II) complex (5) shows greater catecholase activity. On the other hand the trinuclear complexes display efficiency in disproportion reactions of hydrogen peroxide producing water and dioxygen in catalase-like activity and homotrinuclear Cu(II) (6) complex is more active towards catalytic decomposition of hydrogen peroxide. The interaction between these compounds with DNA has also been investigated by agarose gel electrophoresis, the trinuclear copper(II) complexes (5, 6) with H2O2 as a cooxidant exhibited the strongest cleaving activity. <![CDATA[<b>EFFECT OF TEMPERATURE ON CORROSION INHIBITION OF COPPER - NICKEL ALLOY BY TETRAETHYLENEPENTAMINE UNDER FLOW CONDITIONS</b>]]> The corrosion of copper - nickel alloy in hydrochloric acid was investigated at different temperatures, inhibitor concentrations, and corrosive solution rotation rates. Weight loss technique was used to evaluate the corrosion rate data. Tetraethylenepentamine was used as organic corrosion inhibitor, while hydrochloric acid was the corrosive solution. Different parameters, such as inhibitor efficiency, activation energy were obtained. Corrosion rate increased with both temperature and acid rotation rate, while it decreased with increases of Tetraethylenepentamine concentration. Maximum inhibitor efficiency was at lower level of temperature, acid rotation rate and higher level of inhibitor concentration. <![CDATA[<b>KINETIC SPECTROPHOTOMETRIC METHOD FOR THE QUANTITATIVE ANALYSIS OF STREPTOMYCIN SULFATE</b>]]> Kinetic method has been developed for the quantitative analysis of streptomycin. The method is based on the oxidation of the drug with the mixture of potassium iodide and potassium iodate to form a yellow colored product. Two methods are adopted for the determination process, the initial rate method and fixed time, absorbance difference method. Both the method followed Beer's law in the range of 4 μg ml-1- 72 μg ml-1. The linear regression equation of initial rate and fixed time (absorbance difference) method was evaluated to be Rate (U) = -1.026 x 10-6 + 5.93 x 10-4 C and ΔA = -1.63x10-3 + 8.0x10-3C. The limit of detection of initial rate method and fixed time method was obtained to be 0.011 and 0.50, respectively while limit of quantitation upon calculation came out to be 0.032 and 1.5 for initial rate and fixed time absorbance difference methods, respectively. Another important study in the proposed method is the activation parameter study which was done at four different temperatures i.e 298 K, 303 K, 308 K and 313 K. Using the elevated temperature various activation parameters such as change in enthalpy (Ä H), change in entropy (Δ S) and Gibbs free energy (Δ G) was calculated and obtained to be -34.41 kJ mol-1, -143.16 and -77.0 5 9 x 10³ kJ, respectively Probable mechanism of the reaction has been mentioned in the text. <![CDATA[<b>SYNTHESIS, MOLECULAR STRUCTURES, AND ANTIMICROBIAL ACTIVITIES OF <em>N</em>'-(3,5-DIBROMO-2-HYDROXYBENZYLIDENE)-2-FLUOROBENZOHYDRAZIDE AND 7V'-(4-DIETHYLAMINO-2-HYDROXYBENZYLIDENE)-2-FLUOROBENZOHYDRAZIDE</b>]]> Two new carbohydrazone derivatives, N'-(3,5-dibromo-2-hydroxybenzylidene)-2-fluorobenzohydrazide (1), and N'-(4-diethylamino-2-hydroxybenzylidene)-2-fluorobenzohydrazide (2), were prepared by the reaction of 2-fluorobenzohydrazide with 3,5-dibromo-2-hydroxybenzaldehyde and 4-diethylamino-2-hydroxybenzaldehyde, respectively. The compounds were characterized by elemental analyses, infrared spectra, and single crystal X-ray diffraction. The crystal of 1 crystallizes in monoclinic space group C2/c, with unit cell dimensions a = 36.0853(5) Å, b = 10.1711(2) Å, c = 17.3627(5) Å, β = 109.973(2)°, V = 5989.3(2) ų, Z = 16, R1 = 0.0544, wR2 = 0.1300. The crystal of 2 crystallizes in monoclinic space group P2l/c, with unit cell dimensions a = 10.6827(2) Å, b = 16.5256(3) Å, c = 9.8174(1) Å, β = 102.564(2)°, V = 1691.64(5) ų, Z = 4, R1 = 0.0772, wR2 = 0.2156. The compounds were assayed for antibacterial (Bacillus subtilis, Escherichia coli, Pseudomonas fluorescence and Staphylococcus aureus) and antifungal (Aspergillus niger and Candida albicans) activities by MTT method. <![CDATA[<b>SOTALOL CHIRAL SEPARATION BY CAPILLARY ELECTROPHORESIS</b>]]> Differences between the pharmaceutical activity among the enantiomers of sotalol are well known, as R-sotalol and S-sotalol have similar antiarrythmic activities but only the R-enantiomer exhibits β-blocking activity. In this study capillary zone electrophoresis was used for the enantiomeric separation of sotalol using different native and derivatized; neutral and charged; cyclodextrines as chiral selectors. The effects of pH value and composition of the background electrolyte, capillary temperature, running voltage and injection parameters have been investigated. The results showed that only the randomly methylated β-cyclodextrine gave a baseline enantiomeric separation under the optimized conditions; chiral interactions being observed also for hydroxypropyl-β-CD and sulfobutyl ether-β-CD. The analytical parameters of the optimized method were verified and the migration order of the two enantiomers was established. <![CDATA[<b>TEMPORAL TRENDS OF POLYCYCLIC AROMATIC HYDROCARBONS (PAHs) IN A DATED SEDIMENT CORE OF A HIGH ATITUDE MOUNTAIN LAKE</b>: <b>CHUNGARA LAKE- NORTHERN CHILE (18° S)</b>]]> In this study levels, fluxes and temporal trend of PAHs are reported in a sediment core from Chungará Lake (18° S) in Northern Chile. The sediments were obtained by Kayac corer and freeze dried. PAHs were extracted in SOXHLET system and measured by HPLC with diode array detector and fluorescence detection. Sedimentary record chronology was determined using 210Pb isotopes and organic carbon (%) was also measured in sediments. Concentrations (ng g-1 d.w.) of PAHs were low ranging from ~1 to 50. PAHs fingerprint was dominated by 3-ring (21%) and 4-ring. Organic carbon (%) ranged from ~17 to 24 (21±3) and no statistical significant correlation (p<0.05) was detected between OC (%) and PAHs along the sediment core. PAHs fluxes (μg m-2yr-1) fluctuated from ~0.3 (cm 1) to 35 (cm 5) in 1978. LPAHs/HPAHs ratios (0.04 to 3) indicate petrogenic and pyrolytic origin of PAHs. This results contributes with new information of PAHs deposition at high altitudinal lake in Southern Hemisphere. <![CDATA[<b>SYNTHESIS, STRUCTURE AND PHOTOLUMINESCENT PROPERTY OF A CADMIUM COMPLEX WITH 2,4-DICHLOROPHENOXYACETIC ACID</b>]]> A new complex [Cd(2,4-D)2(Im)2(H2O)2] with 2,4-dichlorophenoxyacetic acid (2,4-DH) and imidazole (Im) as ligands has been synthesized and characterized by elemental analysis, IR spectrometry and single-crystal X-ray diffraction. The Cd(II) atom is coordinated in a distorted octahedral geometry, which is defined by two O atoms from two monodentate 2,4-dichlorophenoxyacetate ligands, two N atoms from two imidazole ligands and two water molecules. Intermolecular O-H...O hydrogen bonds form chains, which are connected by N-H...O hydrogen bonds, generating a sheet structure. The molecules are further assembled by π...π stacking interactions to form a two dimensional supramolecular network. <![CDATA[<b>MULTI-INSTRUMENTAL IDENTIFICATION OF ORPIMENT IN ARCHAEOLOGICAL MORTUARY CONTEXTS</b>]]> This paper reports on an unknown yellowish mineral compound found in an archaeological context from Chorrillos cemetery (Calama, Chile) dating to the Early Formative period (800 - 200 B.C.). We used optic microscopy, SEM, EDX, ¹H-RMN, 13C-RMN, and infrared (IR) and Raman spectroscopy to tease out the chemical and molecular composition of the sample. The microscopic images show amorphous yellowish granulates with heterogeneous chemical surfaces. ¹H-RMN and 13C-RMN negative results show that the sample is free of organic matter. The SEM and EDX indicate the presence of arsenic and sulfur in the sample. The IR and Raman analyses suggest the presence of orpiment which is a toxic yellow arsenic sulfide mineral. <![CDATA[<b>SOLID SiO<sub>2</sub>-H<sub>3</sub>PO<sub>4</sub> IS AN EFFICIENT CATALYST FOR CYCLIZATION OF ENONES UNDER SOLVENT-FREE CONDITION</b>: <b>SYNTHESIS AND ANTIMICROBIAL ACTIVITIES OF SOME OXAZINE DERIVATIVES</b>]]> A series of some 1, 3-oxazine amine derivatives including 4-(1-naphthyl)-5,6-dihydro-6-(substituted phenyl)-oxazine-2-amines has been synthesised by solid SiO2-H3PO4 catalyzed solvent-free cyclization of aryl chalcones and urea under microwave irradiation. The yields of the oxazines were more than 80%. The synthesised oxazine amines were characterized by their physical constants, analytical and spectroscopic data. The antimicrobial activities of these oxazine derivatives have been studied using Bauer-Kirby method. <![CDATA[<b>Cr<sup>+6</sup> REMOVAL BY INDIGENOUS BACTERIA IN CONJUNCTION WITH DIFFERENT BIOWASTE MATERIALS</b>: <b>AN ECOFRIENDLY APPROACH</b>]]> Two Cr+6 reducing bacterial strains previously isolated from tannery effluents were used in the present study and identified as Pseudomonas aeruginosa Rb-I and Ochrobacterum intermedium (Rb-2) by 16S rRNA sequencing. Different biowaste materials (waste tea leaves, carrot juice pulp, dry leaves of eucalyptus and rice husk) were assessed for sorption / removal of Cr+6 from aqueous solution of K2Cr2O4. Feasibility of mono and mixed cultures of indigenous bacterial strains was evaluated for Cr+6 removal in conjunction with different biowaste materials. Among all tested biowastes materials, waste tea leaves showed optimum removal of Cr+6 from metal solution alone (77.1%) as well as in combination with bacterial strains (99.4%) after 720 minutes of contact time. Mixed culture of bacterial strains was found to be more efficient in Cr+6 removal than monoculture. The contact time of 720 minutes, pH 7, biomass concentration of 2.5 gram 100 mL-1 , 37°C and shaking speed of 100 rpm were found to be most optimum for optimum Cr+6 sorption alone as well as in combination with bacterial strains. Fourier transform infrared spectroscopy revealed that carboxyl, amino and OH groups present on the waste tea leaves played a significant role in the binding of Cr+6 ions with the biomass. The present study is unique in this respect that this approach involve both living and non-living materials and we could not find any report documenting such findings up to our knowledge. <![CDATA[<b>UV-VIS, NMR AND FT-IR SPECTRA OF TAUTOMERS OF VITAMIN C. EXPERIMENTAL AND DFT CALCULATIONS</b>]]> Experimental and computational analysis of spectroscopic parameters of L-ascorbic acid (vitamin C) and its tautomers was investigated by Density Functional Theory (DFT) using B3LYP method. The optimized geometries and calculated vibrational frequencies were evaluated. The latter was compare with those of experimental values. The λmax values of L-ascorbic acid were found 259 (at pH = 3) experimentally, 238 and 247 nm calculated in the gas and water phase at TD-DFT methods, respectively. The experimental order of υ(Ο-Η) modes was obtained at υ(O3-Η3) > (O6-Ho6) > (O2-H2) > (O5-Ho5). The theoretical orders were calculated at υ(O6-Ho6) > (O2-H2) > (O5-Ho5) > (O3-H3) and υ(O3-H3) > (O5-Ho5) > (O6-Ho6) > (O2-H2), respectively, in the gas phase and aqueous phase. The highest wave number of tautomers (S,Z)-3,5,6-trihydroxy-2-oxohex-3-enoic acid (2), (2Z,4E)-2,3,5,6-tetrahydroxyhexa-2,4-dienoic acid (3), (R)-2-((S)-1,2-dihydroxyethyl)-4,5-dihydroxyfuran-3(2H)-one (4) was calculated for the stretching modes O6-Ho6, O3-H3, O6-Ho6 bonds, respectively, in the gas phase. The experimental and theoretical calculations of proton NMR predicted H3 as the most deshilded proton. <![CDATA[<strong>CRYSTAL STRUCTURE OF HEMIKIS(TETRAKIS(</strong><strong>μ</strong><strong><sub>2</sub></strong><strong>-2-BUTENOATO)-BIS(2-BUTENOATO)-TETRA-AQUA-DI-SAMARIUM) HEMIKIS(BIS(</strong><strong>μ</strong><strong><sub>2</sub></strong><strong>-BUTENOATO)-TETRAKIS(2-BUTENOATO) TETRA AQUA-DI-SAMARIUM) TRIHYDRATE</strong>]]> The structure of the title compound [Sm2(crot)6(H2O)4]2-3(H2O) (I), (crot= crotonate = butenoate = O2CCHCHCH3)] consists of two independent, centrosymmetric dimeric units, of similar composition but diverse coordination, viz., one of them doubly bridged (2×[η2:η1:μ2]) and the remaining one quadruply bridged (2×[η1:η1:μ2], 2×[η2:η1:μ2]). The asymmetric unit is completed by three solvato water molecules, one of them depleted (occupation: 0.735 (14)). The difference in bridging strengths is readily evidenced in the two quite dissimilar Sm···Sm distances observed: 4.1402 (8)Å,(doubly bridged), 3.9439 (8)Å (quadruply bridged). SmO9 polyhedra suyvey similar coordination distances which span the range 2.388 (3)-2.611 (3)Å for one of the Sm cations and 2.357 (3)-2.588 (3)Å for the other. All water hydrogens are involved in H-bonding, leading to the formation of a strongly linked 2D structure parallel to (010). These planar arrays are in turn transversally linked by one single bridging water molecule. There are in addition C= C···C=C p interactions providing both to intra as well as intra planar cohesion. The compound is isomorphous to its Gd isologue¹, but the present description unveils a number of molecular and supramolecular details not discussed therein. <![CDATA[<strong>ANTIOXIDANT AND TOXICITY ACTIVITY <i>IN VITRO</i> OF TWELVE SAFROLE DERIVATIVES</strong>]]> The aim of this study was to determine the influence of substituents in aromatic ring and the side chain of safrole on the antioxidant capacity and toxicity of twelve synthetic derivatives of safrole (S1-S12). Each compound was analyzed by two antioxidant methods: DPPH and bleaching of β-carotene (DBC). Among the derivates of safrol assayed, S5, S6, S9, S10 and S11 showed the strongest antioxidant capacity: DPPH method, first order specific rate constant (0.0152, 0.0211, 0.0432, 0.0317 and 0.0072) and DBC (22.41 ± 0.13%, 10.71 ± 0.05 %, 9.12 ± 0.89 %, 30.97 ± 0.92 % and 19.08 ± 0.31 %), respectively. The toxicity of the active compounds was evaluated by means of two techniques, Artemia salina, LD50 (4466 ± 1057 ppm, 630 ± 108 ppm, 1513 ± 797 ppm, 1585 ± 317 ppm, 1259 ± 242 ppm) and red cells, Haemolysis (1.58 ± 0.98%, 4.02 ± 2.03%, 8.42 ± 1.38%, 2.59 ± 2.31%, 2.92 ± 0.52%), to provide preliminary information that can be used as a basis for further studies to contribute to the search for new antioxidants. <![CDATA[<b>VALIDATION OF A METHOD TO DETECT CENTRAL NERVOUS SYSTEM ACTING DRUGS IN BLOOD BY GC/MS. APPLICATION IN CASES OF DEATH CAUSED BY PHENOTHIAZINES IN THE NORTH OF CHILE</b>]]> A simple and rapid analytical method is developed and validated for the determination of antiepileptic and antipsychotic drugs in human whole blood using a solid-phase extraction and quantification by gas chromatography-mass spectrometry (GC/MS). Prazepam was used as internal standard (IS). The specificity, linearity, intra- and inter-assay precision and accuracy, and extraction recovery were fully evaluated. The limits of detection and quantification were in the range of 0.52 - 0.98 μg/mL and 1.56 - 2.97 μg/mL for antiepileptic drugs (pentobarbital, phenobarbital and carbamazepine) and 1.31 - 2.94 ng/mL and 3.98 - 8.89 ng/mL for antipsychotic drugs (chlorpromazine and thioridazine), respectively. The relative standard deviation (RSD) was less than 7.07%, while the intra-day accuracy was < 3.21% and the inter-day was < 8.80%, referred to RSD. The developed methodology was applied in forensic cases of death caused by phenothiazines in the North of Chile during 2010-2012. <![CDATA[<b>A SIMPLE COLORIMETRIC DETECTOR OF SYMMETRIC 2-(DIALKYLAMINO)ETHANETHIOLS AS PRECURSORS OF V-TYPE NERVE AGENTS</b>]]> A colorimetric detector tube of 2-(dialkylamino)ethanethiols as precursors of V-type nerve agents and their hydrolytic products was designed. The detector is based on a reaction of 2-(dialkylamino)ethanethiols with a chromogenic reagent 4-chloro-7-nitrobenzofurazan (NBD-Cl) in alkaline medium leading to characteristic coloured products. The detection limit in water is of 5 μg/ml, the optimum measurement range being up to 250 μg/ml. The detector also presented a response to some other warfare chemical agents, the colour shade being, however, different. Effects of disturbing substances and organic solvents were studied. <![CDATA[<b>COMBINING CLAYS AND ULTRASOUND IRRADIATION FOR AN <i>O</i>-ACETYLATION REACTION OF <i>N</i>-GLUCOPYRANOSYL AND OTHER MOLECULES</b>]]> A convenient, efficient and fast acetylation combining clays and ultrasound irradiation is described. Some molecules from nature or synthetic source, i.e., D-glucose, glycerol, D-mannitol and 1,2,3-triazolic derivatives such as N-glucosyl sugars and 2-substituted 1,4-naphthoquinone structures were acetylated. This kind of chemistry may be classified as eco-friendly because the reactions take a short time and the catalyst is reusable. <![CDATA[<b>WHY DIELS-ALDER REACTIONS ARE NON-CONCERTED PROCESSES</b>]]> Two exhaustive topological analyses using the Electron Localisation Function (ELF) along the non-polar Diels-Alder reactions of 1,3-butadiene [J. Phys. Chem. A107, 6014 (2003)] and cyclopentadiene [Org. Biomol. Chem. 8, 5495, (2010)] with ethylene established that the bonding changes along these reactions are non-concerted. Herein, the ELF bonding changes along the intramolecular Diels-Alder reaction of 1-(hex-5-enyl)cyclohexa-1,3-diene is analysed. The geometrical restrictions imposed by the tether break the synchronicity in the single bond formation in this non-polar reaction. The present ELF topological analysis along this intramolecular Diels-Alder reaction supports the earlier findings that established the non-concerted nature of Diels-Alder reactions. <![CDATA[<b>MICRO-RAMAN SPECTROSCOPY OF DECORATED POTTERY OF THE DIAGUITA CULTURE FROM IV REGION, CHILE (9<sup>TH</sup>-15<sup>TH</sup> CENTURY AD)</b>]]> Raman spectroscopy pigments on decorated antique Chilean pottery belonging to the Diaguita's culture deposited in Museum of Limarí, have been studied by using Raman spectroscopy. Four ceramic fragments from the unknown contexts were examined. Four colors were found with certainty: red, black, brown and white. Quartz and manganese (kempite) salts, as well as different types of oxide pigments: hematite, tenorite and possibly goethite, were identified. <![CDATA[<b>INHIBITION OF QUORUM SENSING BY DRIMANE LACTONES FROM CHILEAN FLORA</b>]]> Fifteen native Chilean plants were evaluated against the quorum sensing (QS) biosensor AI-1, Chromobacterium violaceum ATCC 12472. Three extracts showed inhibitory activity of QS: Drymis winteri J.R, Psoralea glandulosa L and Peumus boldus. Purification of secondary metabolites from barks of Drimys winteri showed that drimane sesquiterpenes were the main compounds in the tree. Polygodial, drimenol, isodrimeninol, drimenin, isodrimenin, cinnamolide and valdiviolide were isolated and evaluated in QS inhibition assays. Two α,β unsaturated lactones, cinnamolide and valdiviolide, with the carbonyl on position 12 of the drimane skeleton were found to be inhibitors of QS; other drimane lactones were not active. <![CDATA[<b>SYNTHESIS OF <i>N</i>-(HALOGENATED) BENZYL ANALOGS OF SUPERPOTENT SEROTONIN LIGANDS</b>]]> In the last four years a group of extremely potent designer drugs, the N-benzylated phenylethylamines known as the NBOMe series, has surfaced on the street and in the news media. Although data documenting their high affinity and preference for 5-HT2 serotonin receptors abound (5-HT2A receptor activation is generally associated with the action of the "classical" hallucinogens), relatively little is known about the molecular basis of their potency and selectivity. In the setting of a project aiming to evaluate the possible involvement of halogen bonds in the binding of monoaminergic ligands to their receptors, we have begun to synthesize halogenated derivatives of known N-benzylated compounds for their pharmacological study. Here we report the synthesis of new phenylethylamine and tryptamine derivatives incorporating bromine atoms in their N-benzyl moiety. <![CDATA[<b>ANOMALOUS BEHAVIOR OF Ir(III) CYCLOMETALATED COMPLEXES</b>: <b>APPLICATION IN LIGHT-EMITTING ELECTROCHEMICAL CELLS</b>]]> The cationic Ir(III) complex with 7,8-benzoquinoline (bzq) as cyclometalating ligand and 4,4'-diterbutyl-2,2'-bipyridine (tBuB) as ancillary ligand, [Ir(bzq)2(tBuB)](PF6) (1), was utilized in the fabrication of a light-emitting electrochemical cell (LEC). The photophysical properties and the characterization of the LEC device with this complex was compared with literature data for the analogous complex with 2-phenylpyridine (ppy), [Ir(ppy)2(tBuB)](PF6) (2). Complex 1 showed blue shifted emission compared to complex 2. Surprisingly, complex 1 shows lower luminance, efficiency and stability in regard to 2. This behavior correlated well with the low values of quantum yield and lifetime, registered for complex 1 in solution. The performance observed is unexpected, taking into account the emission wavelengths recorded for each complex, and the lesser non radiative deactivation processes expected for a complex with a more rigid ligand as bzq. A possible explanation of this behavior is given in terms of the predominance of a fluorescent emission in the case of the complex 1 instead of a phosphorescent emission, as observed for complex 2. <![CDATA[<b>SIMULTANEOUS DETERMINATION OF ATRAZINE AND SODIUM DICLOFENAC IN NATURAL WATER BY SPECTROPHOTOMETRY APPROACHES</b>]]> Diclofenac (DCF) and Atrazine (ATZ) are pollutants, present in natural waters. To develop new technologies for the abatement of these compounds, it is necessary to develop fast and low cost methods for routine quantification. In this work, two fast and accurate methods for the simultaneous determination of DCF y ATZ in natural waters were developed. These methods are based in spectrophotometric second order derivative (SDS) and partial least-squares (PLS) multivariate calibration from UV-VIS spectroscopic data. Both methods were compared with chromatographic reference methods. Limit of detection (LOD), limit of quantification (LOQ) and recovery values obtained for river water sample were similar. In the case of DCF, the LOD ranged from 3×10-8 (PLS) to 1x10-7 (SDS), while for ATZ, LOD ranged from 1×10-8 (PLS) to 3×10-6 (GC-MS). For DCF, the LOQ ranged from 9×10-8 (PLS) to 9×10-7 (HPLC-UV), while for ATZ, LOQ ranged from 4×10-8 (PLS) to 5×10-6 (GC-MS). For DCF, the recovery (%) ranges from 97 (SDS) to 106 (PLS), while for ATZ, recovery (%) ranges from 91 (PLS) to 99 (SDS).