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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).

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

The inelastic neutron scattering (INS) spectra of cyclopentanone were obtained for pure and 50% CCl4 solution forms. Spectra are compared with infrared and Raman data, and with DFT calculated eigenvectors. This exercise aims to find spectroscopic evidence in the neutron spectra for the presence of C–H⋯O hydrogen bonds. These are weak interactions with an energy of ca. −6 kJ mol−1 as predicted by DFT. The neutron spectra show narrow and sharp bands which allows for an assignment of the vibrational modes. The simulated neutron spectrum of C–H⋯O bonded cyclopentanone dimers matches the experimental spectrum of the pure compound, whereas the monomer simulation monomer matches the experimental spectrum of the diluted solution, meaning that such interaction can be probed by INS. Assignment of the 95 cm−1 band to the νH⋯O anti-translational mode, being supported by DFT results and in agreement with previous literature data, is considered and discussed.

The complete vibrational spectra assignment of dihydrocoumarin is performed through a combined vibrational spectroscopy and DFT calculations approach. To provide effective information, vibrational analysis was also performed for α-pyrone and coumarin related systems. The presence of extra components in the νC O band profile can only be understood by both Fermi resonance and monomer/dimer equilibrium phenomena, the latter established by C–H···O hydrogen bond with Δ H ° value of −8.4 ± 0.9 kJ mol −1 . The analysis of the ν C–H region indicates that both the methylene and aromatic C–H groups have a significant contribution to the formation of C–H···O bonded dimers in liquid dihydrocoumarin.

MCM-41 based materials were prepared with immobilized Mo II and Mo VI active sites based on [MoI 2 (CO) 3 ] and [MoO 2 Cl 2 ] cores, respectively, using a 2-aminopyridine glycidyloxypropyl derivative as anchoring ligand. Suitable characterization by powder X-ray diffraction, FTIR and, 13 C and 29 Si solid state NMR spectroscopy was accomplished. All new materials were successfully used in photodegradation experiments of rhodamine B under aerobic conditions. Control experiments using neat MCM-41 and direct photolysis of rhodamine B were also carried out. All experiments were run without any external source of oxygen other than air. Photocatalytic results show that the presence of Mo and its oxidation state is not innocent in this process. In addition, Mo catalysts act most probably by quenching rhodamine B excited state leading to extended degradation of the dye, through secondary photochemistry, beyond a simple de-ethylation process. Density functional theory (DFT) results corroborate with this showing that when rhodamine B is in excited state the xanthene moiety bond orders change.

The [Mo VI O 2 Cl 2 (thf) 2 ] and [Mo II I 2 (CO) 3 (MeCN) 2 ] precursor complexes, were immobilized in a hybrid periodic mesoporous organosilicas (PMO)-type material. These new hybrid matrix materials were prepared in one pot synthesis, containing the bidentate N , N ′-ligand ( glypy ) in the material. In a second approach, the ordered mesoporous silica MCM- glypy was prepared using a tethered approach by a stepwise procedure. The metal complexes were grafted in both types of materials to obtain heterogeneous pre-catalysts. The modified materials have been characterized by powder X-ray diffraction, N 2 adsorption, and solid-state CP MAS NMR ( 13 C, 29 Si). All metal containing materials were tested as catalysts in epoxidation of 1-octene, cyclooctene and styrene with tert -butylhydroperoxide (TBHP) at 328 K. Selectivity to octene and cyclooctene epoxides was complete. The new PMO materials described in this work are outstanding catalysts for any of the transformations described. In fact, cyclooctene selectivity based on TBHP consumption is found to be almost independent of the mol ratio attesting the efficiency of the catalysts. They are also effective under stoichiometric olefin/oxidant ratio. In addition, a mechanism for acid catalyzed benzaldehyde formation is proposed as well as the conversion of Mo(II) to Mo(VI) under catalysis.

Dioxygenated cyclopentenones are versatile building blocks for the synthesis of several natural products. Herein we report a direct asymmetric synthesis of trans-4,5-dioxygenated cyclopentenone derivatives through base-catalyzed rearrangement of pyranones followed by dynamic kinetic resolution. Milder conditions than previously reported for this rearrangement have been found regarding amine base catalysis, solvent and temperature effects. All data supports a mechanism involving cyclization of an intermediate formed by electrocyclic ring opening of a pyranone-derived enol. We have developed conditions for asymmetric synthesis of trans-4-tert-butoxy-5-hydroxycyclopent-2-enone, in 81% yield and 95% ee, and analogous dioxygenated cyclopentenones, via a lipase induced dynamic kinetic resolution.

The purpose of this study was to develop a simple biological method for the synthesis of Ag nanoparticles (AgNPs) using Lippia citriodora leaves aqueous extract as reducing agent. Transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDX), X-ray diffraction (XRD), and visible absorption spectroscopy (UV-vis) confirmed the reduction of silver ions to AgNPs. Stable, spherical crystalline AgNPs with well defined dimensions (average size of 15-30 nm) were obtained, on treating aqueous silver nitrate with the plant leaf aqueous extract. The kinetic of particles formation was proportional to the effect of reducing agent concentration and was enhanced by the increase of temperature from 25 degrees C to 95 degrees C. Time, temperature and extract concentration did not influence significantly the shape and size of nanoparticles. In order to identify the compounds responsible for the bioreduction of silver ions and stabilization of the AgNPs formed, we investigated the constituents of L. citriodora aqueous extract by high performance liquid chromatography (HPLC) and mass spectrometry (MS). The main compounds found were verbascoside, isoverbascoside, chrysoeriol-7-O-diglucoronide and luteonin-7-O-diglucoronide. The data obtained suggests that the isoverbascoside compound is responsible for Ag(+) ions reduction and act as capping agents of the nanoparticles afterwards.

New hydrotalcite clay materials functionalized with molybdenum(II) complexes holding potential catalytic properties were prepared by a stepwise procedure. The material was first calcined at 823 K for 4 h, to eliminate all the carbonate ions; the layered structure was reconstructed after treatment with a solution of either tryptophane (trpH) or phenylalanine (pheH) in a KOH aqueous solution of dmf at 343 K. Subsequent impregnation with a solution of the organometallic precursor [MoI 2 (CO) 3 (NCCH 3 ) 2 ] led to substitution of the nitriles by the ligands affording the organometallic derivatized clays. The equivalent homogeneous phase complexes [MoI 2 (CO) 3 L] (L = trpH or pheH) were also prepared for comparison purposes. All the materials were characterized by powder X-ray diffraction, FTIR and 13 C CP MAS-DD solid state NMR. The complexes were also characterized by FTIR, UV/vis, elemental analysis, and 1 H and 13 C solution NMR accordingly. Both the complexes and these new materials, the latter containing 3.90 wt.% and 5.42 wt.% of Mo, respectively for HT–trp–Mo and HT–phe–Mo materials, catalyzed the epoxidation of cyclooctene and styrene at 328 K. The heterogeneous catalytic systems performed better showing that the presence of the clay is not innocent. In addition, further oxidation of styrene yielding benzaldehyde has occurred. A possible mechanism is proposed based on the detection of two reaction intermediaries by GC/MS. The heterogeneous catalysts also show superior handling capabilities due to Mo increased resistance to moisture and to separation from reaction medium.

In this work, the usefulness of the Pairs in Molecular Materials (PiMM) approach to elucidate unknown structures of molecular crystals is assessed. This methodology aims to assist the prediction of probable crystal structures from the vibrational spectra, through the identification of the most relevant motifs in the potential energy landscape of the crystal. The method is successfully applied to the elucidation of 4-(dimethylamino)benzaldehyde crystal structure, considered to be “unknown” to illustrate the applicability of the PiMM approach. The proposed crystal structure, based on weak CH⋯O hydrogen bonding and π-stacking interactions, is in full agreement with the recently reported crystal structure.

[Mo(η3-C3H5)X(CO)2(NCCH3)2] (X = Br, 1a; X = Cl, 1b) complexes reacted with the bidentate ligand RN C(Ph)–C(Ph) NR, R = (CH2)2CH3 (DAB, 2) affording [Mo(η3-C3H5)X(CO)2(DAB)] (X = Br, 4a; X = Cl, 4b), which were characterized by elemental analysis, FTIR and 1H and 13C NMR spectroscopy. The modified silylated ligand RN C(Ph) C(Ph) NR, R = (CH2)3Si(OCH2CH3)3 (DAB–Si, 3), was used to immobilize the two complexes in MCM-41 (MCM) mesoporous silica. The new materials were characterized by powder X-ray diffraction, N2 adsorption analysis, FTIR and 29Si and 13C CPMAS solid state NMR spectroscopy. Both the materials and the complexes were tested in the oxidation of cyclooctene and styrene and behaved as active catalyst precursors for cyclooctene and styrene epoxidation with TBHP (t-butylhydroperoxide), leading selectively to epoxides with high conversions and TOFs. Although the homogeneous systems reach 100% conversion of cyclooctene and slightly less for styrene, the loss of catalytic activity in the heterogeneous systems is small, with a 98% conversion of styrene achieved by the chloride containing material.

Reaction of [MnIII(acac)3] and [VIVO(acac)2] with the 1,4-diazabutadiene (DAB) ligands Ph–DAB–(CH2)3R [R = Si(OEt)3(1a); H (1b)] (L) leads to complexes of the type [MnII(acac)2L] and [VIVO(acac)L]Cl in good yields. These complexes were characterised by spectroscopic techniques, and magnetic measurements showed that in the case of the manganese the metal was reduced during the reaction with the nitrogen ligand. The oxovanadium and manganese complexes bearing the ligand with triethoxysilyl groups Ph–DAB–(CH2)3Si(OEt)3(1a) were immobilised in ordered MCM-41 by carrying out a grafting reaction. Tethered complexes of the same type were prepared by treating MCM-41 first with a toluene solution of 1a under reflux; manganese(III) and oxovanadium(IV) precursors were then introduced into the MCM-41-ligand by pore volume impregnation of complex solutions. The modified materials were characterised by powder X-ray diffraction, solid-state NMR (13C, 29Si), FTIR, thermogravimetric studies and low temperature nitrogen adsorption isotherms. The grafted materials contained 0.7 wt% Mn and 0.8 wt% V, while higher metal loadings were achieved when the materials were prepared by tethering (2.9 wt% Mn and 2.4 wt% V). The modified materials are active catalysts for the oxidation of cis-cyclooctene using tert-butylhydroperoxide as oxygen donor, at 328 K, yielding 1,2-epoxycyclooctane as the main reaction product and 1,2-cyclooctanediol as a by-product. The vanadium-containing materials are more efficient epoxidation catalysts than the manganese ones. The catalytic behaviour of the heterogenised catalysts was also compared with that observed in homogeneous phase for the complexes [Mn(acac)2L] and [VO(acac)L]Cl. The vanadium catalysts exhibited the highest catalytic activity, whereas the manganese catalysts were the least active and selective to epoxide formation.

[MoX 2 (CO) 3 (pyca)] (X = I, Br) complexes bearing the ligand C 5 H 4 NCH N(CH 2 ) 2 CH 3 (pyca, 2 ) were prepared and characterized by elemental analysis as well as FTIR and 1 H and 13 C solution NMR spectroscopy. Using the modified ligand C 5 H 4 NCH N(CH 2 ) 3 Si(OEt) 3 (pycaSi, 3 ), they were immobilized in MCM-41 ( MCM ) and in mesoporous materials (i.e., periodic mesoporous organosilica [PMO]) and then characterized by powder X-ray diffraction, N 2 adsorption analysis, FTIR, and 29 Si MAS and CP MAS and 13 C CP MAS solid-state NMR spectroscopy. These new materials and complexes were tested in the oxidation of cyclohexene, cyclooctene, and styrene and in the polymerization of styrene and norbornene. All were good catalyst precursors for olefin epoxidation with TBHP ( t -butylhydroperoxide), leading selectively to epoxides with high conversions and TOFs and achieving high conversions in the second run. This finding, combined with the fact that the materials outperformed the homogeneous complexes, make these catalysts very attractive. They combine the selectivity and activity of the homogeneous species with the features of materials. The iodine-containing materials performed better for styrene (100% conversion), and the bromine-containing materials displayed higher conversion for cyclooctene.

Sertraline hydrochloride (designated as sertraline from now on) is an antidepressive drug with unpleasant effects in the gastric tract. Therefore, improved means of delivery allowing for a more controlled and efficient release were looked for. Two different porous materials, montmorillonite-K10 and MCM-41, were chosen as hosts. The drug was intercalated in the interlayer spacing of the clay by cation exchange and was loaded inside the MCM-41 channels by pore volume impregnation means. Spectroscopic evidence (UV/vis, FTIR, powder X-ray diffraction (XRD) and 13C CP/MAS and 29Si CP/MAS and MAS solid-state NMR), as well as elemental analysis, complemented by DFT calculations, demonstrated the presence of sertraline in the composite materials. The release processes were monitored under in vitro conditions using a simulated body fluid. The release profile from the clay is fast, indicating that a concentration peak is reached in a short period of time, while the release profile from MCM is slower but lasts longer. These differences are discussed on the basis of different therapeutic indications for both materials.

Novel mesoporous MCM-41 type hybrid materials were synthesised by co-condensation of a “flexible” ligand derived from 1,4-diazobutadiene ( 1 ) and tetraethyl orthosilicate in three different ratios (0.027, 0.05, and 0.20) and in the presence of cetyltrimethylammonium bromide as templating agent. Surfactant extraction under mild conditions produced hybrid mesoporous materials with uniform mesoporous scale channels, large pore volumes, and high specific surface areas. These mesoporous organosilicas were characterised by powder X-ray diffraction, nitrogen gas adsorption, 13 C and 29 Si solid state NMR and thermogravimetric analysis. Results from DFT calculations were used for discussing NMR and IR experimental data. The organosilica materials with lower content of organic molecules present uniform 2D-hexagonal mesoporous arrays with pore diameter ranging from 2.0 to 4.0 nm and a surface area ranging from 693 to 803 m 2 /g. The introduction of a larger amount, such as 20%, of organic building block seems to decrease the order of the material and reduce the space available within the pore.

[MX 2 (CO) 3 (DAB)] (M = Mo, W; X = I, Br) ( 5 – 8 ) complexes bearing the 1,4-diazobutadiene (DAB) ligand RN C(Ph) C(Ph) NR [R = (CH 2 ) 3 Si(OEt) 3 ] were immobilized in MCM-41 mesoporous silica. The tethering, stepwise procedure started with treatment of the MCM-41 mesoporous material with a toluene solution of the 1,4-diazobutadiene ligand, under reflux. The molybdenum and tungsten organometallic cores were subsequently introduced into the ligand-silicas by pore volume impregnation of a solution of the complexes [MX 2 (CO) 3 (NCMe) 2 ] (M = Mo, W; X = Br, I). The modified materials were extensively characterized by several techniques, such as FTIR, solid-state MAS and CP MAS NMR ( 13 C, 29 Si), powder XRD, and nitrogen adsorption–desorption measurements. These new materials (containing 2.6–2.9 wt.% Mo or 0.4–0.6 wt.% W) catalyze the ring-opening metathesis polymerization (ROMP) of norbornene (NBE) and norbornadiene at 328 K, in contrast with the very low activity exhibited by the precursor complexes and with their behavior at lower temperature. Addition of AlCl 3 as a co-catalyst enhanced the catalytic performance of the material MCM-DAB-MoBr 2 ( 12 ) in the ROMP of NBE.

A new organic–inorganic hybrid mesoporous MCM-41 type material has been synthesised by co-condensation of tetraethyl orthosilicate (TEOS) and 1,4-diazobutadiene (DAB) ligand RN C(Ph)–C(Ph) NR where R = (CH 2 ) 3 Si(OEt) 3 , in the presence of cetyltrimethylammonium bromide as the structure-directing agent. Surfactant extraction using acidified methanol leaves a hybrid mesoporous material with periodical hexagonal channels, large pore volume and high specific surface area. The material was characterised by powder X-ray diffraction, transmission electron microscopy, nitrogen gas adsorption, 13 C and 29 Si solid-state NMR, FTIR, elemental and thermogravimetry. The ordered structure and the integrity of the ligand structure are preserved after the extraction step.

The effect of solvent polarity versus specific C–H⋯O contacts on the vibrational ν C–H mode is studied using CHCl 3 as a model system. Ab initio SCI–PCM calculations show that the overall shift of the ν C–H band, sometimes ascribed to the C–H⋯O hydrogen bonding, can in fact be explained by the electrostatic interaction with a dielectric environment. The presence of a new ν C–H band – assigned to the C–H⋯O bonded forms – remains as the most reliable evidence of C–H⋯O hydrogen bonding.