Institute Investigaciones En Fisico Quimica Of Cordoba Infiqc

Buenos Aires, Argentina

Institute Investigaciones En Fisico Quimica Of Cordoba Infiqc

Buenos Aires, Argentina

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Pacioni N.L.,Institute Investigaciones En Fisico Quimica Of Cordoba Infiqc | Pierini A.B.,Institute Investigaciones En Fisico Quimica Of Cordoba Infiqc | Veglia A.V.,Institute Investigaciones En Fisico Quimica Of Cordoba Infiqc
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2013

Detailed insights regarding the inclusion process between β-cyclodextrin and the N-methylcarbamates insecticides like Bendiocarb, Carbaryl, Carbofuran and Promecarb, are proposed in bases of experimental and computational methods. The results from Fourier transform infrared spectroscopy, differential scanning calorimetry, induced circular dichroism and molecular dynamics indicate that only in the case of Promecarb the interaction with the macrocycle is produced by the alkyl rest of the molecule. In all other cases the aromatic moiety is the part of the insecticide that is partially included in the cavity of β-cyclodextrin. © 2012 Elsevier B.V. All rights reserved.


Bracamonte A.G.,Institute Investigaciones En Fisico Quimica Of Cordoba Infiqc | Veglia A.V.,Institute Investigaciones En Fisico Quimica Of Cordoba Infiqc
Journal of Photochemistry and Photobiology A: Chemistry | Year: 2013

The cyclodextrins effects on the serotonin (5HT) and 5-hydroxy-3-indolyl acetic acid (5HIA) fluorescence emission in acid and alkaline quenching conditions were analyzed. From Stern-Volmer plots, the quenching constants (KQ) were determined in the presence and absence of β-cyclodextrin (βCD) and hydroxypropyl-β-cyclodextrin (HPβCD). In both media a decrease in the values of KQ was observed in the presence of CDs, as compared with their absence. In acid media, the decrease was: 36-39% with βCD and 48-54% with HPβCD for 5HIA and 5HT, respectively. In basic media, with the neutral receptors, these values are 69-29% with βCD and 56-43% with HPβCD for 5HIA and 5HT, respectively. Moreover, a complete quenching inhibition produced by ionized cyclodextrins was determined for both substrates. The results showed a net protective effect due to the guest inclusion into the cyclodextrin nanocavity. This study is particularly important for analytical determinations in such media. © 2013 Elsevier B.V. All rights reserved.


Rougier N.M.,Institute Investigaciones En Fisico Quimica Of Cordoba Infiqc | Cruickshank D.L.,University of Cape Town | Vico R.V.,Institute Investigaciones En Fisico Quimica Of Cordoba Infiqc | Bourne S.A.,University of Cape Town | And 3 more authors.
Carbohydrate Research | Year: 2011

The hydrolysis reaction of fenitrothion was studied in water containing 2% dioxane and in the presence of native cyclodextrins (α-, β- and γ-CD) and two commercially available modified derivatives, namely, permethylated β- and α-cyclodextrin (TRIMEB and TRIMEA, respectively). The kinetics of the reaction in the presence of TRIMEA could not be measured because the complex formed is insoluble and precipitated even at low concentration. On the other hand, the reaction is only weakly affected by the presence of α-CD. The hydrolysis reaction is inhibited by all the other cyclodextrins. From the kinetic data the association equilibrium constants for the formation of the 1:1 inclusion complexes were determined as 417, 511 and 99 M-1 for β-CD, TRIMEB and γ-CD, respectively. Despite the differences in the association constants for β- and γ-CD, the observed inhibition effect is about the same and this is due to the fact that the rate of hydrolysis in the cavity of γ-CD is smaller than that in the cavity of β-CD. The strongest inhibitor is TRIMEB and this result is consistent with the known structure of the complex in the solid state. © 2010 Elsevier Ltd. All rights reserved.


Cruickshank D.,University of Cape Town | Rougier N.M.,Institute Investigaciones En Fisico Quimica Of Cordoba Infiqc | Vico R.V.,Institute Investigaciones En Fisico Quimica Of Cordoba Infiqc | Rossi R.H.d.,Institute Investigaciones En Fisico Quimica Of Cordoba Infiqc | And 3 more authors.
Carbohydrate Research | Year: 2010

The X-ray crystal structures and thermal stabilities of the inclusion complexes formed between the organophosphate insecticide fenitrothion [O,O-dimethyl O-(3-methyl-4-nitrophenyl) phosphorothioate] and the host compounds TRIMEA and TRIMEB (permethylated α- and β-cyclodextrins, respectively) are reported. In the complex (TRIMEA)2·fenitrothion 1, the guest phosphate ester group is disordered and the molecule is fully encapsulated within a novel TRIMEA dimer in which the secondary rims of the two host molecules are in close contact. In contrast, the complex TRIMEB·fenitrothion 2 is monomeric and the guest molecule is statistically disordered over two positions, with the phosphate group inserted in the host cavity in both cases. Thermal analysis indicated gradual and partial loss of the guest in 1 during heating between 130 °C and the melting point of the complex (∼200 °C), whereas complex 2 displayed significant mass loss only after fusion of the complex at 161 °C. © 2009 Elsevier Ltd. All rights reserved.


Sueldo Occello V.N.,Institute Investigaciones En Fisico Quimica Of Cordoba Infiqc | De Rossi R.H.,Institute Investigaciones En Fisico Quimica Of Cordoba Infiqc | Veglia A.V.,Institute Investigaciones En Fisico Quimica Of Cordoba Infiqc
Journal of Luminescence | Year: 2015

The influence of the macrocyclic compound cucurbit[6]uril (CB6) on the photophysical properties of the fluorophore pyrene (PYR) has been studied. Guest-host interaction was observed by UV-visible spectroscopy and spectrofluorimetry. The fluorescence of PYR was significantly increased in the presence of CB6. The binding equilibrium constants for the complex with 1:1 stoichiometry were determined in HCOOH 55% w/v. The values of the association constants, KA, and the fluorescence quantum yield ratios between complexed and free substrate, φPYR-CB6/φPYR, at different temperatures were (3.1±0.9)×102 M-1 and (5.1±0.2), (3.6±0.5)×102 M-1 and (5.9±0.1), (4.8±0.7)×102 M-1 and (5.5±0.1) at 15.0 °C, 25.0 °C and 40.0 °C, respectively. The enthalpic and entropic contributions to the complexation process were determined, yielding ΔS=(92±3) J mol-1 K-1 and ΔH=(13±1) kJ mol-1. From these results it can be concluded that the complex formation is mainly driven by the entropic term. The forces involved in the complexation are interpreted from the sign and magnitude of the thermodynamic parameters obtained. The partial inclusion of PYR or the formation of a suspended complex is proposed in base of all the data. The interaction is also demonstrated in the solid state by differential scanning calorimetric (DSC) measurements. ©2014 Elsevier B.V. All rights reserved.


Bracamonte A.G.,Institute Investigaciones En Fisico Quimica Of Cordoba Infiqc | Veglia A.V.,Institute Investigaciones En Fisico Quimica Of Cordoba Infiqc
Talanta | Year: 2011

Alternative and sensitive spectrofluorimetric methods for the determination of hydroxyindoles, such as serotonin (5HT) and 5-hydroxyindoleacetic acid (5HIA), were developed on the basis of supramolecular interaction with cyclodextrin (CD) nanocavities (βCD and hydroxypropyl-βCD, HPCD) at different pH values. Both substrates and receptors have acidic protons, therefore the interactions produced in different systems were considered. The effects of neutral CD at pH 2.00 and 6.994, and of anionic CD at pH 13.00 on the specific acid-base species of the compounds at each pH were determined. In all the conditions studied, the fluorescence of the substrates in the presence of CD increased. The association constants (KA, mol-1 L) between the substrates and CD were determined (30-300) and interpreted. A zero-crossing first-derivative spectrofluorimetric method with and without HPCD was developed for the simultaneous determination of 5HT and 5HIA. The limits of detection (LD, ng mL-1) for the best conditions were 0.37 for 5HT and 0.50 for 5HIA at pH 2.00 with HPCD. These LD proved to be better than others reported. The applicability of the direct and derivative spectrofluorimetric methods to urine samples was demonstrated with good recoveries 92-110% and R.S.D. 1-10%. © 2010 Elsevier B.V.All rights reserved.


Montanez J.P.,Institute Investigaciones En Fisico Quimica Of Cordoba Infiqc | Montanez J.P.,CONICET | Gomez S.,CONICET | Gomez S.,National University of Costa Rica | And 2 more authors.
Journal of the Brazilian Chemical Society | Year: 2015

The photocatalytic decomposition of 2-, 3- and 4-chlorobenzoic acids (2CB, 3CB and 4CB, respectively) with TiO2 loaded on HZSM-11 zeolite was investigated. The optimum decomposition rate of 2CB was obtained with TiO2/HZSM-11(30%) (TiO2 30 wt.%) catalyst at a concentration of 1 mg mL-1. 2CB and 3CB decompose at similar rates, but 4CB remains adsorbed on TiO2/HZSM-11(30%) without further degradation. This absorption is attributed to the relative positions of Cl and COOH groups on 4CB. However, this compound can be partially degraded and/or removed from aqueous solutions by TiO2/HZSM-11(50%) catalyst or HZSM-11 zeolite. TiO2/HZSM-11(30%) is stable; it retains its photocatalytic properties after nine cycles, can be easily removed and immediately reused. These are important advantages of TiO2/HZSM-11(30%) over unsupported TiO2, making it a good photocatalyst for the treatment of polluted water. On the other hand, HZSM-11 could be used to selectively adsorb 4CB, thus becoming an alternative method of environmental remediation. © 2015 Sociedade Brasileira de Química.


Cruickshank D.L.,University of Cape Town | Rougier N.M.,Institute Investigaciones En Fisico Quimica Of Cordoba Infiqc | Maurel V.J.,University of Cape Town | De Rossi R.H.,Institute Investigaciones En Fisico Quimica Of Cordoba Infiqc | And 3 more authors.
Journal of Inclusion Phenomena and Macrocyclic Chemistry | Year: 2013

The X-ray crystal structures of the inclusion complexes formed between three pesticides (two organophosphorus insecticides and one chloroacetanilide herbicide) and permethylated β-cyclodextrin (TRIMEB) are reported. The complexes TRIMEB-fenitrothion (1), TRIMEB-fenthion (2) and TRIMEB-acetochlor (3) are members of a commonly occurring isostructural series. The mode of inclusion of the two organophosphate insecticides is very similar, while the acetochlor molecule, which is structurally quite distinct from the two insecticide molecules, adopts a somewhat different position within the TRIMEB cavity. In addition to the structural elucidation of these complexes, their thermal behaviour was investigated using isothermal and non-isothermal thermogravimetry. The isothermal results showed that the dissociation of the guest molecules from the TRIMEB cavities can best be described by two mechanisms, namely a first-order reaction model and a three-dimensional diffusion model. Both the isothermal and non-isothermal methods allowed the determination of the activation energies of the guest loss process for each complex. © 2012 Springer Science+Business Media B.V.

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