DQIO-Artículos
URI permanente para esta colecciónhttps://hdl.handle.net/10953/280
Examinar
Envíos recientes
Ítem Supramolecular forces and their interplay in stabilizing complexes of organic anions: tuning binding selectivity in water(Royal Society of Chemistry, 2019-11-20) Savastano, M.; Bazzicalupi, C.; García-Gallarín, C.; López de la Torre, M.D.; Bianchi, A.; Melguizo, M.How do different supramolecular forces contribute to the stabilization of complexes of organic anions in water? Oftentimes, when debating such a theme, we refer to broad concepts like positive or negative cooperative effects; the focus of the present work is rather on their interplay, i.e. on the way different kinds of stabilizing interactions (salt bridges, H-bonds, anion–π interactions, π–π stacking, solvent effects, etc.) dialogue among themselves. What happens if we tune the strengths of salt bridges by altering the basicity of the anion? What if we change the geometry of the charged group? How does shifting towards more hydrophilic or hydrophobic anions impact the stability of complexes in water? What happens in the solid state? Will aromatic anions go for a π–π stacking or an anion–π interaction mode and do they all behave in the same manner? Does the host/guest size make any difference? What if we play with regiochemistry: will one of the isomers be selectively recognized? Here we present a case study featuring the tetrazine-based ligands L1 and L2 and a series of selected organic anions; potentiometric, NMR, and XRD data and in silico simulations are employed to render such a complex picture.Ítem Anion-π and lone pair-π interactions with s-tetrazine-based ligands(Elsevier, 2019-07-05) Savastano, M.; García-Gallarín, C.; López de la Torre, M.D.; Bazzicalupi, C.; Bianchi, A.; Melguizo, M.Most of traditional and contemporary interest in s-tetrazine derivatives focuses onto their redox properties, reactivity and energy density. In recent times, however, an increasing number of reports highlighted the possible usefulness of the s-tetrazine moiety as a binding site for anionic and electron rich species, according to the high and positive quadrupolar moment of this heterocycle and the consequent strength of anion-π and lone pair-π interactions. Herein, after giving a quick perspective on s-tetrazine properties and on how they foster these types of π interactions, we present statistical and critical examination of the available structural data, doing justice to the debated topic of the existence and directionality of anion- and lone pair-π interactions. Finally, available literature material concerning the usage of s-tetrazine as supramolecular binding site in solution, i.e. paving the way to applications such as molecular recognition and sensing, is presented and discussed.Ítem HBPEI-grafted carbon nanotubes for the effective retention of Pd2+ and Pt2+ through complexation(Royal Society of Chemistry, 2018-06-21) Abdelkader-Fernández, Victor Karim; Morales-Lara, Francisco; López de la Torre, Maria Dolores; Melguizo, Manuel; López Garzón, Francisco Javier; Domingo-García, María; Pérez-Mendoza, ManuelHyperbranched poly(ethyleneimine) (HBPEI) molecules in solution present high capacity to form stable complexes with transition metal ions due to the large number of amino groups ready to form chelates. We grafted HBPEI molecules to a multi-walled carbon nanotube (MWCNT) surface through covalent bonding, preparing solid hybrids which retain the chemical properties of the free poly-alkylamine molecules. In this way, we are able to transfer the complexation capacity of such molecules to a solid material adequate to act as a high-capacity sorbent for metal transition ions. We tested the HBPEI/MWCNT hybrids for the retention of Pd2+ and Pt2+ and the retention values obtained are much larger than those previously reported with fast retention kinetics. The kinetics and the XPS analysis of the metal ion/HBPEI/MWCNT ensemble indicate that the retention takes place through the formation of chelates with two or three nitrogen atoms and with Cl− anions as co-ligands. Moreover, the results allow us to tune the metal loading on the hybrids by controlling the solution conditions. This is important because the XPS valence band analysis demonstrates that metal complexation directly modifies the electronic behaviour of the carbon nanotubes, which supports the stable covalent bond between HBPEI molecules and MWCNT and opens the possibility for tuning the electronic properties of the tubes.Ítem Crystal engineering of high explosives through lone pair-p interactions: Insights for improving thermal safety(Elsevier, 2023-09-15) Savastano, M.; López de laTorre, M.D.; Pagliai, M.; Bazzicalupi, C.; Melguizo, M.; Bianchi, A.In this high-risk/high-reward study, we prepared complexes of a high explosive anion (picrate) with potentially explosive s-tetrazine-based ligands with the sole purpose of advancing the understanding of one of the weakest supramolecular forces: the lone pair-p interaction. This is a proof-of-concept study showing how lone pair-p contacts can be effectively used in crystal engineering, even of high explosives, and how the supramolecular architecture of the resulting crystalline phases influences their experimental thermokinetic properties. Herein we present XRD structures of 4 novel detonating compounds, all showcasing lone pair-p interactions, their thermal characterization (DSC, TGA), including the correlation of experimental thermokinetic parameters with crystal packing, and in silico explosion properties. This last aspect is relevant for improving the safety of high-energy materials.Ítem Expanding graphene properties by a simple S-doping methodology based on cold CS2 plasma(Elsevier, 2019-12-14) Abdelkader-Fernández, Victor Karim; Domingo-García, María; López Garzón, Francisco Javier; Fernandes, Diana M.; Freire, Cristina; López de la Torre, Maria Dolores; Melguizo, Manuel; Godino-Salido, Maria Luz; Pérez-Mendoza, ManuelFor the first time, graphene has been successfully doped with sulfur via short exposition to CS2 microwave cold plasmas, avoiding high-temperature and time/chemicals-consuming treatments. Different S-doped samples were obtained by varying the duration of plasma treatments, reaching a remarkable 2.3 at % of S content after only 5 min of exposition. The S-doped graphenes present several sulfur containing moieties, among which thioether groups resulted to be predominant. These moieties are covalently bond to graphene layers and exhibit good thermal and water stability. In addition, unlike others more conventional methods, S-doping via CS2 plasmas do not damage the structural order of graphene. The influence of sulfur doping on the graphene properties has been assessed through two different tests: on one side, the capture of Pd2+ ions in aqueous solution, and on the other, the electrocatalytic activity towards the production of oxygen from water (OER process). In both cases, the performance of the pristine graphene was significantly enhanced with S-doping. In addition, the capture of Pd2+ allows the formation of sulfur-Pd nanoclusters supported on the graphene surface, which are very useful in electrochemical devices.Ítem Halide and hydroxide anion binding in water(Royal Society of Chemistry, 2018-01-24) Savastano, M.; Bazzicalupi, C.; García-Gallarín, C.; Giorgi, C.; López de la Torre, M.D.; Pichierri, F.; Bianchi, A.; Melguizo, M.The formation of halide and hydroxide anion complexes with two ligands L1 (3,6-bis(morpholin-4- ylmethyl)-1,2,4,5-tetrazine) and L2 (3,6-bis(morpholin-4-ylethyl)-1,2,4,5-tetrazine) was studied in aqueous solution, by means of potentiometric and ITC procedures. In the solid state, HF2 −, Cl− and Br− complexes of H2L22+ were analysed by single crystal XRD measurements. Further information on the latter was obtained with the use of density functional theory (DFT) calculations in combination with the polarizable continuum model (PCM). The presence of two halide or bifluoride HF2 − (F–H–F−) anions forming anion–π interactions, respectively above and below the ligand tetrazine ring, is the leitmotiv of the [(H2L2)X2] (X = HF2, Cl, Br, I) complexes in the solid state, while hydrogen bonding between the anions and protonated morpholine ligand groups contributes to strengthen the anion–ligand interaction, in particular in the case of Cl− and Br−. In contrast to the solid state, only the anion : ligand complexes of 1 : 1 stoichiometry were found in solution. The stability of these complexes displays the peculiar trend I− > F− > Br− > Cl− which was rationalized in terms of electrostatic, hydrogen bond, anion–π interactions and solvent effects. DFT calculations performed on [(H2L2)X]+ (X = F, Cl, Br, I) in PCM water suggested that the ligand assumes a U-shaped conformation to form one anion–π and two salt bridge interactions with the included anions and furnished structural information to interpret the solvation effects affecting complex formation. The formation of hydroxide anion complexes with neutral (not protonated) L1 and L2 molecules represents an unprecedented case in water. The stability of the [L(OH)]− (L = L1, L2) complexes is comparable to or higher than the stability of halide complexes with protonated ligand molecules, their formation being promoted by largely favourable enthalpic contributions that prevail over unfavourable entropic changes.Ítem Ivermectin residues disrupt dung beetle diversity, soil properties and ecosystem functioning: An interdisciplinary field study(Elsevier, 2018-03) Verdú, J.R.; Lobo, Jorge; Sánchez-Piñero, Francisco; Gallego, Belén; Numa, Catherine; Lumaret, Jean-Pierre; Cortez, Vieyle; Ortiz, Antonio J.; Tonelli, Mattia; García-Teba, Juan; Rodríguez-Pereiras, Alexandra; Rey, Ana; Durán, JorgeIvermectin is the most common endectocide used to control parasites affecting livestock. Short-term physiological and behavioural effects of ivermectin on dung beetles may have long-term consequences for beetle populations and ecosystem functioning. Long-term effects of the use of ivermectin can be estimated by comparing dung assemblages and ecosystem functions in areas with conventional ivermectin-treated livestock and environmentally similar areas in which livestock are not treated with veterinary medical products (organic farming). In this study, we investigated both short-term and long-term effects of the administration of ivermectin on the characteristics of dung beetle assemblages and the services they provided in a protected area (Doñana National Park, SW Spain). We examined short-term dung colonization, dwelling, relocation, and disaggregation rates and the associations between these processes and the key assemblage parameters of species richness, abundance, biomass and functional diversity. Furthermore, we analysed changes in soil physical-chemical properties and processes. Short-term differences were observed in the total amount of dung relocated by dung beetles at different colonization vs. emigration stages, suggesting that dung beetles in this area were affected by the recent treatments of livestock with ivermectin. Moreover, short-term effects could also be responsible for the significant differences in dung spreading rates between sites. Conventional use of ivermectin disrupted ecosystem functioning by affecting species richness, abundance and biomass. The decrease in diversity parameters was related to a reduction in the functional efficiency, which resulted in the long-term accumulation of dung on the ground and considerable changes in soil functionality.Ítem Nontoxic effects of thymol, carvacrol, cinnamaldehyde, and garlic oil on dung beetles: A potential alternative to ecotoxic anthelmintics.(Public Library of Science (PLOS), 2023-12) Verdú, J.R.; Cortez, Vieyle; Rosa-García, Rocío ez-Piñero; Ortiz, Antonio J.; Lumaret, Jean-Pierre; García-Prieto, Urcesino; García Romero, Carmelo; Sánchez-Piñero, FranciscoThe sustainability of the traditional extensive livestock sector will only be possible if healthy dung-decomposing insect communities are preserved. However, many current pharmaceutical anthelmintics are harmful to dung beetles, their presence can have a negative impact on biological systems. Phytochemical anthelmintics are an alternative to ecotoxic synthetic pharmaceutical anthelmintics, although ecotoxicological tests of their possible indirect effects on dung beetles are required to demonstrate their viability. In this study, the potential ecotoxicity of thymol, carvacrol, cinnamaldehyde and garlic oil (diallyl disulfide and diallyl trisulfide) were tested for the first time. Inhibition of antennal response was measured as a relevant parameter by obtaining relevant toxicity thresholds derived from concentration‒response curves, such as the IC50. All phytochemical compounds tested were demonstrated to be suitable alternative candidates to the highly ecotoxic compound ivermectin, considering their non-toxicity to nontarget organisms. Residues of the phytochemical antiparasitics found in cattle droppings were extremely low, even undetectable in the case of diallyl disulfide and diallyl trisulfide. Furthermore, our results showed that none of the phytochemical compounds have ecotoxic effects, even at extremely high concentrations, including those almost 1000 times higher than what is most likely to be found in dung susceptible to ingestion by dung beetles in the field. We can conclude that the four selected phytochemical compounds meet the requirements to be considered reliable alternatives to ecotoxic veterinary medicinal products, such as ivermectin.Ítem Mating Disruption of the Olive Moth Prays oleae (Bernard) in Olive Groves Using Aerosol Dispensers(MDPI, 2021-12) Ortiz, Antonio; Porras, Andrés; Marti, Jordi; Tudela, Antonio; Rodríguez-González, Alvaro; Sambado, PaoloThe olive moth (OM), Prays oleae (Bern.) (Lepidoptera: Yponomeutidae), is a major olive grove pest worldwide; however, until now, very few studies have investigated the effectiveness of mating disruption (MD) techniques against this pest. Experiments were carried out for two successive years (2019 and 2020) in three different olive groves in Andalucía (Southern Spain) to evaluate mating disruption’s efficacy in controlling the OM from the first to the third generation. The effectiveness of MD formulations against the three generations of OM was assessed by determining the percentage of infested olive fruits, the reduction of pheromone trap catches, and the number of affected inflorescences in both MD-treated and untreated control olive groves. The number of release points (one or two aerosol devices per ha) was also evaluated. In all years and trials, the mean number of males caught in traps placed in the MD-treated plots was significantly lower than untreated sites. Mating disruption registered a high suppression of male captures (>75%) in treated plots for two consecutive seasons. Concerning infested olive fruits, substantial reductions (about 80%) were observed in the MD plots of locations B and C, and a reduction of about 40% was detected in location A, compared to the control plot. Results showed that the installation of two aerosol devices/ha reduced fruit damage below 20% of infested olive fruits except for one site where a reduction of about 71% in the MD plot was recorded in 2019. Although few significant differences were associated with OM male catches and infested olive fruits between plots treated with one aerosol/ha and two aerosols/ha in most of the comparisons, significant differences in the number of olive inflorescences infested by P. oleae were found, suggesting a similar performance between the two tested aerosol densities. Results of two-year field trials in Andalucía demonstrated the potential of Mister P X841 aerosol devices as an effective tool for controlling the olive moth, P. oleae.Ítem Biomagnification and body distribution of ivermectin in dung beetles(www.nature.com, 2020) Verdú, J.R.; Cortez, Vieyle; Ortiz, Antonio J.; Lumaret, Jean-Pierre; Lobo, Jorge; Sánchez-Piñero, FranciscoA terrestrial test system to investigate the biomagnification potential and tissue-specific distribution of ivermectin, a widely used parasiticide, in the non-target dung beetle Thorectes lusitanicus (Jekel) was developed and validated. Biomagnification kinetics of ivermectin in T. lusitanicus was investigated by following uptake, elimination, and distribution of the compound in dung beetles feeding on contaminated faeces. Results showed that ivermectin was biomagnified in adults of T. lusitanicus when exposed to non-lethal doses via food uptake. Ivermectin was quickly transferred from the gut to the haemolymph, generating a biomagnification factor (BMFk) three times higher in the haemolymph than in the gut after an uptake period of 12 days. The fat body appeared to exert a major role on the biomagnification of ivermectin in the insect body, showing a BMFk 1.6 times higher than in the haemolymph. The results of this study highlight that the biomagnification of ivermectin should be investigated from a global dung-based food web perspective and that the use of these antiparasitic substances should be monitored and controlled on a precautionary basis. Thus, we suggest that an additional effort be made in the development of standardised regulatory recommendations to guide biomagnification studies in terrestrial organisms, but also that it is necessary to adapt existing methods to assess the effects of such veterinary medical products.Ítem First assessment of the comparative toxicity of ivermectin and moxidectin in adult dung beetles: Sub-lethal symptoms and pre-lethal consequences(2018-10) Verdú, J.R.; Cortez, Vieyle; Martinez-Pinna, Juan; Ortiz, Antonio; Lumaret, Jean Pierre; Lobo, Jorge; Sánchez-Piñero, Francisco; Numa, CatherineAmong macrocyclic lactones (ML), ivermectin (IVM) and moxidectin (MOX) potentially affect all Ecdysozoan species, with dung beetles being particularly sensitive. The comparative effects of IVM and MOX on adult dung beetles were assessed for the first time to determine both the physiological sub-lethal symptoms and pre-lethal consequences. Inhibition of antennal response and ataxia were tested as two intuitive and ecologically relevant parameters by obtaining the lowest observed effect concentration (LOEC) values and interpolating other relevant toxicity thresholds derived from concentration-response curves (IC50, as the concentration of each ML where the antennal response is inhibited by half; and pLC50, as the quantity of ingested ML where partial paralysis was observed by half of treated individuals) from concentration-response curves. Both sub-lethal and pre-lethal symptoms obtained in this study coincided in that IVM was six times more toxic than MOX for adult dung beetles. Values of LOEC, IC50 and pLC50 obtained for IVM and MOX evaluated in an environmental context indicate that MOX, despite needing more time for its elimination in the faeces, would be half as harmful to dung beetles as IVM. This approach will be valuable to clarify the real impact of MLs on dung beetle health and to avoid the subsequent environmental consequences.