Use of nanomaterials in the pretreatment of water samples for environmental analysis

The challenge of providing clean drinking water is of enormous relevance in today’s human civilization, being essential for human consumption, but also for agriculture, livestock and several industrial applications. In addition to remediation strategies, the accurate monitoring of pollutants in water sup-plies, which most of the times are present at low concentrations, is a critical challenge. The usual low concentration of target analytes, the presence of in-terferents and the incompatibility of the sample matrix with instrumental techniques and detectors are the main reasons that renders sample preparation a relevant part of environmental monitoring strategies. The discovery and ap-plication of new nanomaterials allowed improvements on the pretreatment of water samples, with benefits in terms of speed, reliability and sensitivity in analysis. In this chapter, the use of nanomaterials in solid-phase extraction (SPE) protocols for water samples pretreatment for environmental monitoring is addressed. The most used nanomaterials, including metallic nanoparticles, metal organic frameworks, molecularly imprinted polymers, carbon-based nanomaterials, silica-based nanoparticles and nanocomposites are described, and their applications and advantages overviewed. Main gaps are identified and new directions on the field are suggested.publishe

Illuminating a Solvent-Dependent Hierarchy for Aromatic CH/π Complexes with Dynamic Covalent Glyco-Balances

CH/π interactions are prevalent among aromatic complexes and represent invaluable tools for stabilizing well-defined molecular architectures. Their energy contributions are exceptionally sensitive to various structural and environmental factors, resulting in a context-dependent nature that has led to conflicting findings in the scientific literature. Consequently, a universally accepted hierarchy for aromatic CH/π interactions has remained elusive. Herein, we present a comprehensive experimental investigation of aromatic CH/π complexes, employing a novel approach that involves isotopically labeled glyco-balances generated in situ. This innovative strategy not only allows us to uncover thermodynamic insights but also delves into the often less-accessible domain of kinetic information. Our analyses have yielded more than 180 new free energy values while considering key factors such as solvent properties, the interaction geometry, and the presence and nature of accompanying counterions. Remarkably, the obtained results challenge conventional wisdom regarding the stability order of common aromatic complexes. While it was believed that cationic CH/π interactions held the highest strength, followed by polarized CH/π, nonpolarized CH/π, and finally anionic CH/π interactions, our study reveals that this hierarchy can be subverted depending on the environment. Indeed, the performance of polarized CH/π interactions can match or even outcompete that of cationic CH/π interactions making them a more reliable stabilization strategy across the entire spectrum of solvent polarity. Overall, our results provide valuable guidelines for the selection of optimal interacting partners in every chemical environment, allowing the design of tailored aromatic complexes with applications in supramolecular chemistry, organocatalysis, and/or material sciences.This investigation was supported by research grants PID2019-107476GB-I00 and PID2022-141085NB-I00, funded by MCIN/AEI/10.13039/501100011033 and by ERDF A way of making Europe. A.G.S. is grateful for grant RYC2021-031704-I funded by MCIN/AEI/10.13039/501100011033 and by European Union NextGeneration EU/PRTR. L.D.-C. and A.V. respectively are grateful for grants BES-2017-080618 and PRE2020-093392, funded by MCIN/AEI/10.13039/501100011033 and by ESF Investing in your future, for a predoctoral contract each.Peer reviewe

Unexpected Stereocontrolled Access to 1α,1′β-Disaccharides from Methyl 1,2-Ortho Esters

Mannopyranose-derived methyl 1,2-orthoacetates (R = Me) and 1,2-orthobenzoates (R = Ph) undergo stereoselective formation of 1α,1′β-disaccharides, upon treatment with BF₃·Et₂O in CH₂Cl₂, rather than the expected acid-catalyzed reaction leading to methyl glycosides by way of a rearrangement–glycosylation process of the liberated methanol

Capsaicin Fluidifies the Membrane and Localizes Itself near the Lipid–Water Interface

Capsaicin is the chemical responsible for making some peppers spicy hot, but additionally it is used as a pharmaceutical to alleviate different pain conditions. Capsaicin binds to the vanilloid receptor TRPV1, which plays a role in coordinating chemical and physical painful stimuli. A number of reports have also shown that capsaicin inserts in membranes and its capacity to modify them may be part of its molecular mode of action, affecting the activity of other membrane proteins. We have used differential scanning calorimetry, X-ray diffraction, ³¹P NMR, and ²H NMR spectroscopy to show that capsaicin increases the fluidity and disorder of 1,2-palmitoyl-<i>sn</i>-glycero-3-phosphocholine membrane models. By using ¹H NOESY MAS NMR based on proton–proton cross-peaks between capsaicin and 1-palmitoyl-2-oleoyl-<i>sn</i>-glycero-3-phosphocholine resonances, we determined the location profile of this molecule in a fluid membrane concluding that it occupies the upper part of the phospholipid monolayer, between the lipid–water interface and the double bond of the acyl chain in position <i>sn</i>-2. This location explains the disorganization of the membrane of both the lipid–water interface and the hydrophobic palisade

Low Temperature Production of Formaldehyde from Carbon Dioxide and Ethane by Plasma-Assisted Catalysis in a Ferroelectrically Moderated Dielectric Barrier Discharge Reactor

Plasma-assisted catalysis of the reaction between CO₂ and C₂H₆ in a single-pass, ferroelectrically moderated dielectric barrier discharge reactor has been studied at near ambient temperature as a function of physicochemical and electrical reaction variables. The presence of small amounts of a vanadia/alumina catalyst dispersed on the BaTiO₃ ferroelectric markedly enhanced the production of formaldehyde, the focus of this work. A maximum HCOH selectivity of 11.4% (defined with respect to the number of ethane carbon atoms consumed) at ∼100% ethane conversion was achieved, the other products being CO, H₂O, H₂, CH₄ and a small amount of C₃H₈. N₂O was also an effective partial oxidant (HCOH selectivity 8.9%) whereas use of O₂ led to complete combustion, behavior that may be rationalized in terms of the electron impact excitation cross sections of the three oxidants. Control experiments with the coproducts CH₄ and C₃H₈ showed that these species were not intermediates in HCOH formation from C₂H₆. Analysis of reactor performance as a function of discharge characteristics revealed that formaldehyde formation was strongly favored at low frequencies where the zero-current fraction of the duty cycle was greatest, the implication being that plasma processes also acted to destroy previously formed products. A tentative reaction mechanism is proposed that accounts for the broad features of formaldehyde production

Spectroscopic and Thermodynamic Evidence of Dimer and Trimer Hydrogen Bonded Complex Formation between Chloroform and 2‑Butanone. Excess Molar Enthalpy for the Chloroform + 2‑Butanone Binary System at 303 K

FT-Raman and FT-infrared spectra of pure chloroform (A) and 2-butanone (B), as well as of the binary system chloroform + 2-butanone, were recorded to investigate the type and nature of the intermolecular complexes formed when both chemicals are mixed. The optimized structures and vibrational frequencies for 2-butanone, chloroform, and their 1:1 and 1:2 complexes were calculated by means of density functional theory (DFT) techniques using the B3LYP functional combined with the 6-31G­(d,p) and 6-311++G­(d,p) basis set. The recorded FTIR and Raman spectra confirm the existence of these types of hydrogen-bonded complexes, making it possible, furthermore, to calculate the heteroassociation constants. Heat of mixing at 303 K over the whole mole fraction range at atmospheric pressure was also measured. The excess molar enthalpy was fitted to a Redlich–Kister-type equation, using least-squares to obtain its dependence on concentration. The ideal associated solution model was also used to calculate these equilibrium constants among the chemical species in solution, which compare well with that calculated with the spectral determinations and the enthalpy of hydrogen bond formation. Furthermore, the McGlashan–Rastogi linearization test was also used to provide thermodynamic evidence about the stoichiometry of the formed complexes

Heterologous Microarray Analysis of Transcriptome Alterations in <i>Mus spretus</i> Mice Living in an Industrial Settlement

This work demonstrates the successful application of a commercial oligonucleotide microarray containing <i>Mus musculus</i> whole-genome probes to assess the biological effects of an industrial settlement on inhabitant <i>Mus spretus</i> mice. The transcriptomes of animals in the industrial settlement contrasted with those of specimens collected from a nearby protected ecosystem. Proteins encoded by the differentially expressed genes were broadly categorized into six main functional classes. Immune-associated genes were mostly induced and related to innate and acquired immunity and inflammation. Genes sorted into the stress-response category were mainly related to oxidative-stress tolerance and biotransformation. Metabolism-associated genes were mostly repressed and related to lipid metabolic pathways; these included genes that encoded 11 of the 20 cholesterol biosynthetic pathway enzymes. Crosstalk between members of different functional categories was also revealed, including the repression of serine-protease genes and the induction of protease-inhibitor genes to control the inflammatory response. Absolute quantification of selected transcripts was performed via RT-PCR to verify the microarray results and assess interindividual variability. Microarray data were further validated by immunoblotting and by cholesterol and protein-thiol oxidation level determinations. Reported data provide a broad impression of the biological consequences of residing in an industrial area