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Focusing on the pertinent research on dual activity (as probes and cancer inhibitors), two novel Eu and Tb lanthanide complexes were prepared in this work alongside their binuclear counterparts holding Cu as the secondary metal. Complexes that did not contain copper were found to be less effective in promoting cancer cell death, in contrast to their bimetallic counterparts, which could function as inhibiting molecules while sequestering Cu from the tumoral environment. The ANOVA test results showed that, for A549 cells, the Eu complexes didn’t present relevant differences, whereas the results for their Tb counterparts were confirmed as being different. All complexes were structurally characterized by using high-resolution mass spectrometry, vibrational, electronic and fluorescence spectroscopy. TD-DFT calculations were carried out to assess the nature of the electronic transitions and ANOVA test to evaluate whether each pair of complexes was similar concerning their activity on the cell lines (null hypothesis). Data showed that the mononuclear Eu and Tb complexes had, as expected, fluorescent properties while their binuclear counterparts (holding Cu) did not. The mononuclear complexes were titrated with Cu2+ confirming their ability to sequester the latter in a tumor microenvironment. All synthesized compounds were pH responsive, although they maintained their structures in the physiological pH range and were investigated in cell viability tests with HeLa (breast) and A549 (lung adenocarcinoma) cancer cell lines towards assessing how they induce cell death. Overall, this work showed that these complexes could play an important role as bioprobes as well as anticancer agents published

In this work, we explored how solvents can affect olefin oxidation reactions catalyzed by MCM-bpy-Mo catalysts and whether their control can be made with those players. The results of this study demonstrated that polar and apolar aprotic solvents modulated the reactions in different ways. Experimental data showed that acetonitrile (aprotic polar) could largely hinder the reaction rate, whereas toluene (aprotic apolar) did not. In both cases, product selectivity at isoconversion was not affected. Further insights were obtained by means of neutron diffraction experiments, which confirmed the kinetic data and allowed for the proposal of a model based on substrate–solvent crosstalk by means of hydrogen bonding. In addition, the model was also validated in the ring-opening reaction (overoxidation) of styrene oxide to benzaldehyde, which progressed when toluene was the solvent (reaching 31% styrene oxide conversion) but was strongly hindered when acetonitrile was used instead (reaching only 7% conversion) due to the establishment of H-bonds in the latter. Although this model was confirmed and validated for olefin oxidation reactions, it can be envisaged that it may also be applied to other catalytic reaction systems where reaction control is critical, thereby widening its use.

Fish fraud is a problematic issue for the industry. For it to be properly addressed will require the use of accurate, rapid, and cost-effective tools. In this work, near infrared reflectance spectroscopy (NIRS) was used to predict nutritional values (protein, lipids, and moisture) as well as to discriminate between sources (farmed vs. wild fish) and conditions (fresh or defrosted fish). Samples of five whitefish species—Alaskan pollock (Gadus chalcogrammu), Atlantic cod (G. morhua), European plaice (Pleuronectes platessa), common sole (Solea solea), and turbot (Psetta maxima)—including farmed, wild, fresh, and frozen ones, were scanned by a low-cost handheld near infrared reflectance spectrometer with a spectral range between 900 and 1700 nm. Several machine learning algorithms were explored for both regression and classification tasks, achieving precisions and coefficients of determination higher than 88% and 0.78, respectively. Principal component analysis (PCA) was used to cluster samples according to classes where good linear discriminations were denoted. Loadings from PCA revealed bands at 1150, 1200, and 1400 nm as the most discriminative spectral regions regarding classification of both source and condition, suggesting the absorbance of OH, CH, CH2, and CH3 groups as the most important ones. This study shows the use of NIRS and both linear and non-linear learners as a suitable strategy to address fish fraud and fish QC.

The biobased polyester poly(ethylene 2,4-furanoate) (2,4-PEF) is a potentially interesting yet insufficiently studied polymer whose resistance to crystallization fundamentally stems from the asymmetric nature of the 2,4-furandicarboxylic acid monomer. A combination of vibrational spectroscopy (infrared, Raman and inelastic neutron scattering) and ab initio calculations has been used to assess the conformational and regiochemistry preferences of 2,4-PEF. The latter polymerizes following a random distribution of monomer orientation, thereby rendering the formation of periodic interchain C-H···O contacts wholly unfeasible and ultimately favoring the formation of randomly coiled chains based on gauche-ethylene glycol segments. In the absence of C-H···O stabilization, the ordered crystalline arrangement is disfavored and polymer chains - adopting several quasi iso-energetic structures - prefer to solidify into an amorphous mess.

Nanosized MoO2 can be prepared by different protocols, which yield different morphologies of the nanoparticles. Among their many properties, they can serve as catalysts for styrene oxidation (among other olefins), which is an industrially relevant transformation. In this work, we prepared MoO2 nanosized catalysts by two slightly different hydrothermal protocols using ethylenediamine and either Fe2O3 or hydroquinone. When used in catalysis, kinetic data evidenced that depending on the synthesis protocol of MoO2, induction periods occur (for the catalyst prepared with hydroquinone) with obvious different kinetic profiles and, in addition, product selectivity was also affected. To gain some insight on what is behind these results of the catalytic activity, a combined approach of studies has been conducted. DRIFT and inelastic neutron scattering (INS) techniques were used to assess the adsorbed species at the surface of both the fresh (DRIFT and INS) and recovered (INS) catalysts. Results from this study showed that when hydroquinone was used, an organic shell coated the MoO2 nanoparticles, which negatively influenced the catalytic performance.

The two layered double hydroxides ZnAl-LDH and MgAl-LDH were functionalized with bis(4-HOOC-phenyl)-acenaphthenequinonediimine) (H2BIAN), leading to the intercalation of its dianion, which in a second step reacted with [Mo(CO)3X2(NCMe)2] (X = I, Br), affording four new materials. These materials and the two complexes [Mo(CO)3X2(H2BIAN)2] (X = I, Br) were tested in the olefin epoxidation reaction with substrates cis-cyclooctene, styrene, 1-octene, trans-hex-3-en-1-ol, and R-(+)-limonene, using tert-butylhydroperoxide (tbhp) as oxidant. The new catalysts were particularly good for cis-cyclooctene and styrene (100% conversions) and at least one heterogeneous catalyst was comparable to the homogeneous ones in the epoxidation of 1-octene and trans-hex-3-en-1-ol. The homogeneous catalysts were the best to oxidize R-(+)-limonene (higher conversions).

The dynamics of 2-methoxybenzaldehyde, 4-methoxybenzaldehyde, and 4-ethoxybenzaldehyde in the solid state are assessed through INS spectroscopy combined with periodic DFT calculations. In the absence of experimental data for 4-ethoxybenzaldehyde, a tentative crystal structure, based on its similarity with 4-methoxybenzaldehyde, is considered and evaluated. The excellent agreement between calculated and experimental spectra allows a confident assignment of the vibrational modes. Several spectral features in the INS spectra are unambiguously assigned and torsional potential barriers for the methyl groups are derived from experimental frequencies. The intramolecular nature of the potential energy barrier for methyl rotation about O– CH3 bonds compares with the one reported for torsion about saturated C–CH3 bonds. On the other hand, the intermolecular contribution to the potential energy barrier may represent 1/3 of the barrier height in these systems. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

Fucus vesiculosus is a brown macroalgae used in food and generally considered safe to be consumed, according to EU Directive (EC 258/97). The aim of this study is to analyze the effect of food preparation on F.vesiculosus of different origins on what concerns its chemical constituents and final bioactivities. The aqueous extract of the seaweeds were obtained at different temperatures, similar to food preparation and then purified by SPE. The compound identification was carried out by Liquid Chromatography High Resolution Mass Spectrometry (LC-HRMS/MS) and algae extracts microstructure were observed by Scanning Electron Microscopy (SEM). The activities were determined by using antioxidant activity, inhibition of acetylcholinesterase (AChE) and 3-hidroxi-3-methyl-glutaril-CoA (HMG-CoA) reductase (HMGR) together with Caco-2 cells line simulating the intestinal barrier. The activity of AChE and the HMGR were inhibited by the extracts giving IC50 values of 15.0 &plusmn, 0.1 &micro, g/mL and 4.2 &plusmn, g/mL, respectively and 45% of the cholesterol permeation inhibition. The main compounds identified were phlorotannins and peptides derivatives. The mode of preparation significantly influenced the final bioactivities. Moreover, the in vitro results suggest that the preparation of F. vesiculosus as a soup could have hypercholesterolemia lowering effect.

This work presents a comprehensive spectroscopic analysis of crystalline isoniazid, one of the main drugs in tuberculosis chemotherapy, using a blend of spectroscopic and computational methods. Mid- and far-infrared, Raman, and inelastic neutron scattering spectroscopies, with contribution of isotopic substitution are combined with discrete and periodic DFT quantum chemical calculations. This combined approach successfully reproduces the whole spectral range, allowing a sound assignment of all the vibrational bands. Previous misassignments have been corrected and several spectral features of isoniazid crystal are reported for the first time. Virtues and limitations of the computational approach (periodic and discrete) are also discussed in light of the present state-of-the-art in the field.

A thorough vibrational spectroscopy and molecular modeling study on poly(ethylene 2,5-furandicarboxylate) (PEF) explores its conformational preferences, in the amorphous and crystalline regions, while clarifying structure–property correlations. Despite the increasing relevance of PEF as a sustainable polymer, some of its unique characteristics are not yet fully understood and benefit from a deeper comprehension of its microstructure and intermolecular bonding. Results show that in the amorphous domains, where intermolecular interactions are weak, PEF chains favor a helical conformation. Prior to crystallization, polymeric chains undergo internal rotations extending their shape in a zigzag pattern—an energetically unfavorable geometry which is stabilized by C–H···O bonds among adjacent chain segments. The zigzag conformation is the crystalline motif present in the α and β PEF polymorphs. The energy difference among the amorphous and crystalline chains of PEF is higher than in PET poly(ethylene terephthalat...

Au nanoparticles (AuNPs) were immobilized on S-containing amino acids (cysteine and methionine) Mg/Al hydrotalcite clay in both bulk and exfoliated (colloidal) forms. The Au nanoparticles were prepared by a biomimetic method using an anti-oxidant tea extract to reduce the Au salt solution. The performance of bulk and exfoliated clays with Au nanoparticles in aerobic olefin epoxidation was assessed with very interesting results. Both catalysts were very active towards the epoxide products; selectivity was found to be dependent on the catalyst form. The exfoliated catalysts yielded higher product stereoselectivity in the case of limonene epoxidation. These results can be explained by the existence of a confined environment around the AuNPs structures provided by the clay nanosheets wrapping the nanoparticles, modulating how substrates interact with the catalytic active centres. Based on experimental data mechanistic proposals were also rationalized for these catalysts showing how they assist the catalytic process.

The structure and dynamics of crystalline 4-(dimethylamino) benzaldehyde, 4DMAB, are assessed through INS spectroscopy combined with periodic DFT calculations. The excellent agreement between experimental and calculated spectra is the basis for a reliable assignment of INS bands. The external phonon modes of crystalline 4DMAB are quite well described by the simulated spectrum, as well as the modes involving low-frequency molecular vibrations. Crystal field splitting is predicted and observed for the modes assigned to the dimethylamino group. Concerning the torsional motion of methyl groups, four individual bands are identified and assigned to specific methyl groups in the asymmetric unit. The torsional frequencies of the four methyl groups in the asymmetric unit fall in a region of ca. 190 ± 20 cm−1, close to the range of values observed for methyl groups bonding to unsaturated carbon atoms. The hybridization state of the X atom in X-CH3 seems to play a key role in determining the methyl torsional frequency.

Undaria pinnatifida is a brown alga, largely used as food in oriental countries. The purpose of this work was to analyze several bioactivities that might be present in different food preparations, relating them with the compounds present in the extracts. Aqueous extracts cooked, like a soup, as well as used in a salad, by simulating U. pinnatifida digestion with pancreatin were prepared. The soup preparation had anti-acetylcholinesterase activity as well as 3-hydroxy3-methyl-glutaryl coenzyme A reductase inhibition capacity, the use of 1 mg/mL, for both enzymes, caused 50% enzyme activity inhibition. The extracts produced changes in HepG2 cell proteome, mainly in the 148 kDa proteins. U. pinnatifida in salads hardly released phlorotannins to the digestive tract. The in vitro studies suggested that a soup prepared from this seaweed could deliver bioactive compounds, phlorotannins and small peptides that may facilitate the gastro-intestinal motility and reduce the cholesterol biosynthesis. info:eu-repo/semantics/publishedVersion

Layered double hydroxides (LDHs) have attracted attention as green materials due to their catalytic ability in benign aqueous solvents. We here demonstrate the synthesis of colloidal Co–Al LDH nanoclusters with an average size of

A Co/Al layered double hydroxide material was synthesized in both bulk and exfoliated (colloidal) forms. Anion exchange with methionine allowed immobilization of Au nanoparticles previously prepared by a biomimetic method using an anti-oxidant tea aqueous extract to reduce the Au salt solution. The catalytic performance of bulk and exfoliated clays Au-hybrid materials was assessed in aerobic olefin epoxidation. Both catalysts were very active towards the epoxide products and with very interesting substrate conversion levels after 80 h reaction time. The Au-exfoliated material, where the nanosheets work as large ligands, yielded higher product stereoselectivity in the case of limonene epoxidation. This arises from a confined environment around the Au nanoparticles wrapped by the clay nanosheets modulating access to the catalytic active centres by reagents. Mechanistic assessment was also accomplished for styrene oxidation by DFT methods.

A 2:1 Co/Al layered double hydroxide (LDH) material was synthesized with Cl– anions intercalated and then anion exchanged with deprotonated methionine. This allowed further immobilization of Au nanoparticles. The catalytic performance of the set of three LDH materials for comparative benchmarking was assessed in the aqueous reduction of nitroaromatic compounds and of rhodamine dyes in the presence of NaBH4. All catalysts were found to be very active for the nitro-to-amine reduction. The same was observed for the dyes, where reduction rhodamine 6G was faster than that of rhodamine B, for all catalysts. While the Au-containing catalyst was apparently the one showing the best catalytic activity the LDH with Cl– was found to follow it closely in terms of catalytic performance. In addition, while the LDH catalyst with Au was prone to deactivation by amine products in recycling experiments, the LDH catalyst with Cl– was almost insensitive to that, which is a large advantage. These results showed that using a catalyst based on first-row metals for efficient processes is possible and addresses current sustainable and environmental concerns.

Iron oxide magnetic nanoparticles were synthesized with different sizes (11 and 30 nm). Subsequently they were shelled with a silica layer allowing grafting of an organic phosphine ligand that coordinated to the [MoI2(CO)3] organometallic core. The silica layer was prepared by the Stöber method using either mechanical (both 11 and 30 nm nanoparticles) or ultrasound (30 nm only) stirring. The latter nanoparticles once coated with silica were obtained with less aggregation, which was beneficial for the final material holding the organometallic moiety. The Mo loadings were found to be 0.20, 0.18, and 0.34 mmolMo·g−1 for MNP30-Si-phos-Mo,MNP11-Si-phos-Mo, and MNP30-Sius-phos-Mo, respectively, with the ligand-to-metal ratio reaching 4.6, 4.8, and 3.2, by the same order, confirming coordination of the Mo moieties to two phos ligands. Structural characterization obtained from powder X-ray diffraction (XRD), scanning electron microscopy (SEM)/ transmission electron microscopy (TEM) analysis, and Fourier-transform infrared (FTIR) spectroscopy data confirmed the successful synthesis of all nanomaterials. Olefin epoxidation of several substrates catalyzed by these organometallic nano-hybrid materials using tert-butyl hydroperoxide (tbhp) as oxidant, achieved very good results. Extensive testing of the catalysts showed that they are highly active, selective, recyclable, and efficient concerning oxidant consumption.

The Mo(II) complexes [MoX 2 (CO) 3 (BDC)] (X = I, Br; H 2 BDC = 2,2′-bipyridine-5,5′-dicarboxylic acid) were immobilized by intercalation in two layered double hydroxides (LDH), containing Zn/Al (synthesized) and Mg/Al (commercial), as shown by infrared and 13 C solid state NMR spectroscopies, and X-ray powder diffraction. Their catalytic activity was studied in olefin oxidation, using as oxidant tert -butylhydroperoxide (tbhp), and was compared with the activity of the related [MoX 2 (CO) 3 (bpy)] complexes (bpy = 2,2′-bipyridine). cis -Cyclooctene, styrene, 1-octene, trans -hex-3-en-1-ol, and R -(+)-limonene were the substrates tested. All the catalyst showed in average a high selectivity toward the epoxide of each substrate (above 90%, except for styrene), with variable conversions, but none of the heterogeneous catalysts proved to be more active than the homogeneous ones. The same or higher activity in a second catalytic run, as observed in most reactions, suggests a good recycling capability.

MoO2 nanoparticles with tremella-like morphology have been synthesized and characterized. Characterization by powder X-ray diffraction (XRD) and transmission electron micrographs (TEM) microscopy made possible to estimate that the nanosheets have ca. 12 nm and aggregate to form tremella-like structures. The resulting MoO2 nanoparticles were used as catalyst for epoxidation of several olefins. The use of tert-butylhydroperoxide (tbhp), H2O2 and cumenehydroperoxide (chp) as oxygen sources was screened under different reaction conditions, namely, solvent and temperature. The results from the catalytic experiments show that this catalyst was very efficient leading to very high conversion and product selectivity levels. In addition, the use of oxidant:olefin ratios close to 1 show that this catalyst is very efficient conducting olefin epoxidation. Further details are discussed in the work. The catalyst showed overall excellent performance with tbhp. When using H2O2, the catalyst showed good activity, which is very relevant as well. All these achievements contribute with a step forward in the development of more environmentally friendly processes.

A Zn complex was stepwise intercalated in a Mg/Al layered double hydroxide material (HT) holding phenylalanine in its interlayer spacing. The material was characterized by powder X-ray diffraction, FTIR and solid state 13C NMR spectroscopy. By analogy, the [Zn(phe)(H2O)](NO3) complex bearing deprotonated phenylalanine (phe) amino acid as ligand and a labile water molecule, mimicking biological moieties, was also prepared as model and characterized by HR-MS, FTIR and 1H solution NMR spectroscopy. Both the Zn-containing HT material and model complex were tested in the catalytic epoxidation of cyclooctene, styrene and 1-octene. All tests were carried out with hydrogen peroxide (H2O2) or tert-butylhydroperoxide (TBHP), leading selectively to epoxides in most cases. Both temperature and oxygen source were found to be key factors in controlling epoxide selectivity, especially when using H2O2, where results were outstanding. Furthermore, the reported results show that the catalytic performance of this Zn system is at the same level of similar systems, holding heavier metals and less sustainable, found in the literature, while the Zn-containing HT catalyst had also the advantage of recyclability.

A thorough vibrational portrait of 4-fluorobenzaldehyde is presented, covering Infrared (Mid- and Far-), Raman and Inelastic Neutron Scattering (INS) spectra. Periodic DFT calculations (CASTEP) of a model 4FB crystal proved useful for vibrational assignment, yielding estimates of experimental spectra with near one-to-one correspondence – including the correct estimation of overtone and combination modes. A striking similarity among the Far-IR spectrum of liquid 4FB and that estimated based on a periodic structure indicates that the solid-liquid transition induces soft structural changes which leave most vibrational modes unaffected – except for those directly involved in Csingle bondH…O bonding, where crystal field splitting is observed. published

Bacterial nanocellulose (BC)-based composites containing poly(2-hydroxyethyl methacrylate) (PHEMA), poly(methacroylcholine chloride) (PMACC) or poly(methacroylcholine hydroxide) (PMACH) were characterized by inelastic neutron scattering (INS) spectroscopy, combined with DFT (density functional theory) calculations of model systems. A reasonable match between calculated and experimental spectral lines and their intensities was used to support the vibrational assignment of the observed bands and to validate the possible structures. The differences between the spectra of the nanocomposites and the pure precursors indicate that interactions between the components are stronger for the ionic poly(methacrylate) derivatives than for the neutral counterpart. Displaced anions interact differently with cellulose chains, due to the different ability to compete with the O&ndash, H&middot, &middot, O hydrogen bonds in cellulose. Hence, the INS is an adequate technique to delve deeper into the structure and dynamics of nanocellulose-based composites, confirming that they are true nanocomposite materials instead of simple mixtures of totally independent domains.

The present work emphasizes the value of periodic density functional theory (DFT) calculations in the assessment of the vibrational spectra of molecular crystals. Periodic calculations provide a nearly one-to-one match between the calculated and observed bands in the inelastic neutron scattering (INS) spectrum of crystalline 4-phenylbenzaldehyde, thus validating their assignment and correcting previous reports based on single molecule calculations. The calculations allow the unambiguous assignment of the phenyl torsional mode at ca. 118&ndash, 128 cm&minus, 1, from which a phenyl torsional barrier of ca. 4000 cm&minus, 1 is derived, and the identification of the collective mode involving the antitranslational motion of CH&middot, &middot, O bonded pairs, a hallmark vibrational mode of systems where C-H&middot, O contacts are an important feature.

The present work aims at exploiting a polyelectrolyte nanocomposite based on poly(4-styrene sulfonic acid) (PSSA) and bacterial cellulose (BC) as an eco-friendly proton-exchange membrane (PEM) for application in microbial fuel cells (MFCs). The PSSA/BC-based PEM was confirmed as a true nanocomposite by inelastic neutron scattering (INS) vibrational spectroscopy. Moreover, this PEM exhibited thermal stability up to 155 °C, Young's modulus of 11.7 ± 0.9 GPa, ion exchange capacity of 1.85 mmol g−1, and maximum protonic conductivity of 1.73 S m−1. The application of the PSSA/BC nanocomposite membrane in a single-chamber lab-scale MFC with a pure culture of Shewanella frigidimarina yielded a maximum power density of 2.42 mW m−2, open circuit voltage of 0.436 V, and internal resistance of 15.1 kΩ. These results are superior to those obtained with a commercial Nafion® membrane and, thus, confirm the potential of this bio-based PSSA/BC nanocomposite as a PEM for MFCs.

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We present a case study on the vibrational coupling of lattice phonons to the electronic 4f7 (8S7/2)–4f65d1 (eg) transition of divalent europium in the hydrides and deuterides LiMH3 and LiMD3 (M = Sr and Ba). For low doping concentrations, these compounds show extraordinarily well-resolved vibronic fine structures at low temperatures. Besides luminescence emission spectroscopy of the europium-doped compounds, we carried out inelastic neutron scattering (INS) experiments of the europium-free compounds. The phonons coupling to the electronic transition are identified, and a good agreement between the vibronic and the INS data is found. The frequencies of the low-energy acoustic modes do not significantly change upon replacing hydride by deuteride, whereas a decrease by a factor of approximately 2 can be observed for the higher energy optic modes. Furthermore, we compare these experimental results to density functional calculations performed with the Vienna Ab initio Simulation Package. Knowledge of the phon...

This work explores the dynamics of hydrogen bond networks in cellulose through inelastic neutron scattering (INS) and periodic CASTEP calculations. Estimated spectra were based on the crystal structure of cellulose Iα and Iβ and replicate the INS spectrum of cellulose samples with remarkable similarity, allowing a reliable assignment of INS bands to vibrational modes of cellulose. Comparison of cellulose samples from varied sources, from bacterial to kraft pulp, allows the identification of characteristic INS bands, arising from C2-OH torsional motions, which easily identify which allomorph-Iα or Iβ-is prevalent. A high crystallinity index is revealed by the presence of well-defined INS bands associated with highly cooperative CH bending modes along the chain. Hydrating kraft cellulose samples clearly affects those INS bands related with the hydroxymethyl group, identified as the preferred binding site for water molecules. At high humidity content level, a significant proportion of the water molecules is aggregated in clusters within the amorphous cellulose domains. The formation of ice microcrystals leads to a partial disruption of the hydrogen-bond network, as can be concluded from the observed red-shift of the torsional OH vibrational modes. The full assignment and interpretation of cellulose's INS spectra herein provided is a sound basis for future use of INS spectroscopy in the characterization of functionalized cellulose fibers and composite materials.

The suitability of porous materials to immobilize and release under control bioactive molecules prompted us to design and study delivery systems of Vitamin A (VitA). This molecule, relevant in several physiological functions, is easily oxidized. Commercial VitA was immobilized in two different clays, montmorillonite K-10 (MMT) and sepiolite (SEP), and in MCM-41, by impregnation. Characterization of the resulting hybrid materials by XRD, FTIR and 13C and 29Si (MAS) NMR spectroscopies revealed its presence. The photo-stability tests showed decreased degradation of VitA in the clays, compared to MCM-41 and the pure VitA, while thermostability is observed until ∼100 °C. The kinetics of the release depended on the structural features of the support material and the pH. Sepiolite originated a classic profile of increasing amount of VitA with time, indicating that no oxidation was taking place. In both montmorillonite and MCM-41 the amount of released VitA dropped after ∼2 hours, reflecting oxidation. Oxidation and degradation products obtained when VitA was immobilized in MCM-41, both under nitrogen and in air, were identified by mass spectrometry experiments. Sepiolite is therefore a suitable material to use in controlled release of VitA, since it appears to prevent oxidation.

In this work a mesoporous nanocomposite material comprising helical chiral channels and with embedded magnetic iron oxide nanoparticles in its Si-based MCM-41 type framework was synthesized. Afterwards, a bipyridine derivative was grafted to the inner surface used as ligand to coordinate a molybdenum(II) precursor complex. The Mo loading was found to be 2.42 wt% Mo, corresponding to 0.26 mmolMo g−1. The successful preparation of this helical mesoporous material was evidenced by an extensive characterization process using powder XRD, SEM/TEM analysis, FT-IR and Raman spectroscopies, TGA analysis and also by SQUID measurements. Selective adsorption of enantiopure D- and L-phenylalanine shows that the material has a preference for the D- over the L- enantiomer. This provides evidence that the channels are chiral (although the particles are not) and that it is useful for chiral recognition applications. It also sets the explanation to the good results achieved in the selective epoxidation of olefins. The resulting material was tested as catalytic precursor in the epoxidation of cis-cyclooctene, styrene, R-(+)-limonene and trans-hex-2-en-1-ol, using tert-butyl hydroperoxide (tbhp) as oxygen source. The catalytic studies show that the synthesized material yields selectively the desired epoxides of the tested substrates with very good results, especially at higher temperatures and using toluene as solvent. The major achievement of the catalyst was an outstanding stereocontrol of the reaction products imposed by the confined space of the helical chiral channels. Therefore these materials offer an important contribution to asymmetric catalysis and to fields where chiral recognition is a relevant concept.

The main goal of this study is to validate the Steinrath index predictions toward copper corrosion in two different soils (loamy and sandy), nonmodified and modified with chlorides, reaching the typical levels of seawater and Steinrath indexes varying between (−3) and (−8). Average corrosion rates between 4.5±0.3 and 124.5±0.5 μm/y showed to be in agreement with the predictions of the Steinrath index. The copper surfaces, covered with corrosion products, were analyzed by visual observation, scanning electron microscopy coupled to energy dispersive spectroscopy, powder x-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. Cuprite (Cu2O) has been identified by XRD, as the main constituent on all of the surfaces, with traces of atacamite (Cu2(OH)3Cl) on top of the Cu2O layer. FTIR spectra suggest that sulfate, silicate, and/or hydroxyls are likely to be present.

Metal oxide nanoparticles MoO 2 with tremella-like morphology have been synthesized and characterized. The solvothermal synthesis method is a new procedure starting from MoO 3 mixed with ethylenediamine and hydroquinone as reducing and assisting agents, respectively. Characterization by powder XRD and TEM microscopy made possible to estimate that the nanosheets have ca. 12 nm and aggregate to form tremella-like structures. The resulting MoO 2 nanoparticles were used as catalyst for epoxidation of several olefins. The use of tert -butylhydroperoxide (TBHP) and cumenehydroperoxide (CHP) as oxygen sources was screened under different reaction conditions, namely, solvent and temperature. The results from the catalytic experiments show that this catalyst is very active leading to very high conversion and product selectivity. Efficiency tests evidence that for some transformations the MoO 2 nanoparticles can work under olefin:oxidant stoichiometric ratios which is certainly an advantage, although induction periods are observed under these conditions. The induction periods are directly correlated with the amount of oxidant and tend to decrease with increasing concentration of the oxidant. The catalyst is also recyclable without severe loss of activity and no major structural changes as well. This catalyst also levels its performance with related systems found in the literature.

Molybdenum trioxide (MoO3) nanoparticles with an average size below 100 nm were prepared by solvothermal synthesis of nano-crystalline molybdenum dioxide (MoO2) and subsequent thermal oxidative annealing. The successful preparation of this type of nanoparticles was confirmed by evidence obtained from characterization by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) analysis and Fourier transform infrared spectroscopy (FTIR). The MoO3 nanoparticles were tested as catalytic precursor in the epoxidation of cis-cyclooctene, styrene, R-(+)-limonene and trans-hex-2-en-1-ol, using tert-butylhydroperoxide (tbhp) as oxygen source under different reaction conditions, namely, various solvents and temperatures. The catalytic studies show that the MoO3 nanoparticles perform selective epoxidation of the tested substrates with very high yield, especially at high temperature and using toluene as solvent. Furthermore, the catalyst remains active across several reaction cycles with virtually no loss of activity.

New asymmetric Cu(II)/Cu(II) and Ni(II)/Ni(II) binuclear Schiff base complexes were synthesised via a one-pot reaction introducing two different aldehyde building blocks (R = H, t-Bu). These complexes were successfully electropolymerised to afford new metallopolymers using different sweep scan rates (50, 100 and 200 mV s−1) between 0 and 1.4 V. Surface coverage – (Γ) values were determined assuming ligand-based conduction and are of about 10−7 mol cm−2 for both polymers. Atomic force microscopy (AFM) images showed morphological differences between Cu(II) and Ni(II) polymers with root mean square roughness (Rq) higher for the former. DFT studies support the ligand based electropolymerisation mechanism, based on the electron density of the cation at the para position of the phenolate ring, and suggest that copper dimers prefer slipped square planar geometry, with one Cu–O weak bond between adjacent units, rather than stack as in Ni(II) dimers, in agreement with the AFM observations.

The solids choline chloride and urea, mixed in a 1 : 2 molar proportion, form the iconic deep eutectic solvent “Reline”. A combination of computational and vibrational spectroscopy tools, including inelastic neutron scattering (INS), have been used to probe intermolecular interactions in the eutectic mixture. Reline's experimental spectra were estimated using discrete and periodic ab initio calculations of a molecular aggregate with two choline chloride and four urea units. This is the minimum size required to achieve satisfactory agreement with experiment, as smaller clusters cannot represent all of reline's significant intermolecular interactions. The INS spectrum of reline, compared with that of pure choline chloride, reveals a displacement of chloride anions away from their preferred positions on top of choline's methyl groups, whose torsional movement becomes less hindered in the mixture. Urea, which adopts a planar (sp2) shape in the crystal, becomes non-planar (sp3) in reline, a feature herein discussed for the first time. In reline, urea molecules form a wide range of hydrogen bonds, from soft contacts to stronger associations, the latter being responsible for the deviation from ideality. The chloride's interactions with choline are largely conserved at the hydroxyl end while becoming weaker at the cationic headgroup. The interplay of soft and strong interactions confers flexibility to the newly formed hydrogen-bond network and allows the ensemble to remain liquid at room temperature.

The organometallic fragment [MoI 2 (CO) 3 ] was coordinated to magnetic iron oxide nanoparticles of different sizes (average size of 11 and 30 nm) which have been previously coated with a silica shell and grafted with a pyridine derivative ligand. The Mo loading was found to be approximately 0.37 wt-% Mo and 0.57 wt-% Mo, corresponding to 0.150 mmol Mo g −1 and 0.230 mmol Mo g −1 for materials MNP 30 -Si-inic-Mo and MNP 11 -Si-inic-Mo , respectively. Preparation of these organometallic decorated magnetic nanoparticles was further confirmed by evidence obtained from extensive characterization by powder XRD, SEM/TEM analysis, as well as from data of 57 Fe Mossbauer and FTIR spectroscopy. Olefin epoxidation of a variety of substrates promoted by these organometallic nano-hybrid materials using tbhp as oxidant, was performed with very good results. The catalytic studies show that the catalysts yield selectively the desired epoxides of a series of olefins. In addition, these catalysts are found to work under a wide temperature range and over several catalytic cycles without notorious performance loss in most cases.

Glucuronolactones were used as precursors for N9 and N7 purine nucleosides containing glucuronic acid derivatives in their structures. Acetylated N-benzylglucofuran- and glucopyranuronamides were synthesized in a few steps from glucofuranurono-6,3-lactone. They were converted into the corresponding furanosyl and pyranosyl uronamide-based nucleosides by N-glycosylation with silylated 2-acetamido-6-chloropurine in the presence of trimethylsilyl triflate. The triacetylated bicyclic lactone was coupled itself with the nucleobase to give bicyclic N9,N7 nucleosides. Tri-O-acetylglucopyranurono-6,1-lactone was used for the first time as a glycosyl donor for N-glycosylation, and led to β-configured N9- and N7-linked purinylglucuronides under reaction conditions similar to those used with the 1-O-acetyl-substituted glycosyl donors. The cholinesterase inhibitory profiles of the synthetic nucleosides bearing glucuronic acid derivatives as glycons were evaluated, and they showed moderate selective acetylcholinesterase inhibitory activities (Ki = 14.78–50.53 μM). The best inhibition was shown by the furanosyl N9-linked uronamide-based purine nucleoside.

Nifedipine, a potent calcium-channel blocking agent, widely used for treating hypertension has been immobilized inside inorganic matrix materials. The drug was intercalated in Montmorillonite K10 clay by cation exchange, and loaded by an adsorption method inside the channels of mesoporous MCM-41. Spectroscopic evidence (FTIR, powder X-ray diffraction (XRD)) as well as elemental analysis thermal analysis and electron microscopy revealed the preparation of the drug-loaded materials. Release profiling in a simulated body fluid from MCM-41 is fast, indicating that a concentration peak is reached in a short period of time, while the release profile from K10 is much slower. The release profile from MCM-41 leads to higher drug solubility compared even with neat drug solubility, which is advantageous in a drug known for its low solubility (ca. 20 μg mL–1). The same is true for K10 clay although its slow release kinetics leave it behind. Spectroscopic data supports this fact by showing that intermolecular host–guest interactions occur thus leading to the observed kinetic effects in the release experiments. In addition it is found that nifedipine inside the host materials is more resistant to photodegradation than in its pure form thus showing another important feature of the hybrid organic/inorganic formulation, as evidenced by GC data.

Helical mesoporous materials of the MCM-41 type are important materials that can be prepared by onepot synthesis procedures with a co-surfactant. A control of the characteristics at a local level is of the most important in the view of the applications of such materials. However, there are not many studies relating such features with synthetic approaches. In this work, we prepared both helical and regular channel materials from Si-based MCM-41 type. Afterward, a bpy derivative was used as ligand to coordinate MoII/VI. The complexes and the new materials were tested as the catalytic precursors in the epoxidation of cis-cyclooctene, styrene, 1-octene, R-(+)-limonene and trans-hex-2-en-1-ol, using tert-butylhydroperoxide (TBHP) as oxidant. Although almost all the catalysts were 100% selective toward the epoxide, the conversions were in general good. The major achievement of these catalysts is an outstanding stereocontrol of the reaction products. In addition, these catalysts were found to be very effective under several circumstances. This is certainly an important contribution for such concept and may render such materials further applications where chiral recognition is important.