Iridium-Complexed Dipyridyl-Pyridazine Organosilica as a Catalyst for Water Oxidation.

The heterogenization of metal-complex catalysts to be applied in water oxidation reactions is a currently growing field of great scientific impact for the development of energy conversion devices simulating the natural photosynthesis process. The attachment of IrCp*Cl complexes to the dipyridyl-pyridazine N-chelating sites on the surface of SBA-15 promotes the formation of metal bipyridine-like complexes, which can act as catalytic sites in the oxidation of water to dioxygen, the key half-reaction of artificial photosynthetic systems. The efficiency of the heterogeneous catalyst, Ir@NdppzSBA, in cerium(IV)-driven water oxidation was thoroughly evaluated, achieving high catalytic activity even at a long reaction time.

Carboxymethylcellulose/Hydrotalcite Bionanocomposites as Paraben Sorbents.

In this work, we synthesized several bionanocomposites of hydrotalcites containing carboxymethylcellulose as interlayer anion (HT-CMC) to be used as sorbents for parabens, a family of emergent pollutants (specifically, for 4-methyl, 4-propyl and 4-benzylparaben). Bionanocomposites were obtained by ultrasound-assisted coprecipitation and characterized by X-ray diffraction analysis, fourier transform infrared and raman spectroscopies, elemental and thermogravimetric analysis, scanning and transmission electron microscopies and X-ray fluorescence. All materials proved to be efficient sorbents for parabens through a process conforming to a pseudo second-order kinetics.

Ru- and Ir-complex decorated periodic mesoporous organosilicas as sensitizers for artificial photosynthesis.

A versatile and facile strategy based on an inverse electron demand Diels-Alder reaction between 5-norbornen-2-yltriethoxysilane and a tetrazine derivative has been established for the synthesis of a new triethoxysilane precursor containing dipyridylpyridazine units. Such a precursor has been incorporated into the mesostructure of an ethylene-bridged periodic mesoporous organosilica (PMO) material through a one-pot synthesis a co-condensation method. Upon attachment of Ru- and Ir-complexes to the pendant N-chelating heterocyclic ligands, the resulting decorated PMOs have acted as photosensitizers in artificial photosynthetic systems.

Efficient Removal of Nonylphenol Isomers from Water by Use of Organo-Hydrotalcites.

The presence of potent organic endocrine-disrupting chemicals (EDCs) in natural aquifers can have adverse impacts on public health and the environment. 4-nonylphenol, one such EDC, can be efficiently removed from water by adsorption onto a clayey material. In this work, we created an effective sorbent for this purpose by using co-precipitation and subsequent ion-exchange to intercalate the organic anion deoxycholate into a Mg/Al hydrotalcite.

Copper-complexed dipyridyl-pyridazine functionalized periodic mesoporous organosilica as a heterogeneous catalyst for styrene epoxidation.

A new heterogeneous catalyst has been synthesized by immobilization of a copper complex on dipyridyl-pyridazine functionalized periodic mesoporous organosilica (dppz-vPMO). This ordered support was first prepared by a co-condensation reaction between vinyltriethoxysilane and 1,2-bis(trimethoxysilyl)ethane and further post-functionalized through a hetero Diels-Alder reaction with 3,6-di-2-pyridyl-1,2,4,5-tetrazine. Techniques such as XRD, N isotherms, TEM, C NMR, XPS and DRIFT, among others, were employed to characterize the surface functionalized materials.

Thiol-Functionalized Ethylene Periodic Mesoporous Organosilica as an Efficient Scavenger for Palladium: Confirming the Homogeneous Character of the Suzuki Reaction.

This work describes the synthesis of thiol-functionalized periodic mesoporous organosilicas (PMOs) prepared using the precursor 1-thiol-1,2-bis(triethoxysilyl)ethane, alone or mixed with 1,2-bis(triethoxysilyl)ethane. The thiol groups incorporated into the structure were found to be efficient for palladium binding. This has allowed these materials to be used as catalysts in the Suzuki cross-coupling reaction of bromobenzene and phenylboronic acid.

Oleate Epoxidation in a Confined Matrix of Hydrotalcite.

Oleate ion was intercalated into a hydrotalcite obtained using a conventional precipitation method and an alternative, novel method involving microwave-assisted ion exchange. The latter method gave a more crystalline hydrotalcite with better textural properties than the former. The spacing between layers in the hydrotalcites was used to epoxidize the double bond in oleate ion.

Luminescent Graphene-Based Materials via Europium Complexation on Dipyridylpyridazine-Functionalized Graphene Sheets.

Graphene-based materials exhibit outstanding physical properties and so are potentially applicable in a great variety of fields. Unlike their corresponding oxides, graphite and graphene are not prone to functionalization. Diels-Alder reactions are among the scarce reactions that they can occur without disrupting their conjugated sp systems.

Identification of pigments in the Annunciation sculptural group (Cordoba, Spain) by micro-Raman spectroscopy.

A highly flexible method based on micro-Raman spectroscopy was used to examine pigment traces on an Annunciation sculpture group dating from the late Middle Ages. The group comprises a statue of the Archangel Gabriel and another of the Virgin Mary. Both are currently housed in the Archaeological Museum of Cordoba, southern Spain.

A Comparative Study of Particle Size Distribution of Graphene Nanosheets Synthesized by an Ultrasound-Assisted Method.

Graphene-based materials are highly interesting in virtue of their excellent chemical, physical and mechanical properties that make them extremely useful as privileged materials in different industrial applications. Sonochemical methods allow the production of low-defect graphene materials, which are preferred for certain uses. Graphene nanosheets (GNS) have been prepared by exfoliation of a commercial micrographite (MG) using an ultrasound probe.

Fast ultrasound-assisted synthesis of highly crystalline MIL-88A particles and their application as ethylene adsorbents.

Highly crystalline MIL-88A particles have been successfully synthesized via fast ultrasound-assisted processes. The influence of the sonication generator and synthesis time on the structure, crystallinity, morphology and surface area of the materials were studied in detail. Under this modified ultrasonic method, X-ray diffraction patterns of MIL-88A particles showed highly crystalline structures in contrast to those reported in literature.

Spectroscopic analysis of corrosion products in a bronze cauldron from the Late Iberian Iron Age.

Selected bronze fragments unearthed at Cerro de la Cruz (Almedinilla, southern Spain) were analyzed to determine the chemical composition of the corrosion products formed on their surface. The fragments came from a large bronze cauldron used in an Iberian village that was devastated in the mid II century BCE - possibly around 141 BCE. The fragments were analyzed by using various instrumental techniques including electron scanning microscopy coupled to energy dispersive X-ray spectroscopy (SEM-EDS), X-ray fluorescence (XRF) spectroscopy, and also by X-ray diffraction (XRD) and micro-Raman spectroscopy.

Coumarin Derivatives Solvent-Free Synthesis under Microwave Irradiation over Heterogeneous Solid Catalysts.

A suitable methodology of synthesis of coumarin derivatives by Pechmann reaction over heterogeneous solid acid catalysts in a free solvent media under microwave irradiation is described. Resorcinol, phenol and ethyl acetoacetate were selected as model reactants in the Pechmann condensation. The catalytic activity of several materials-Amberlyst-15, zeolite β and sulfonic acid functionalized hybrid silica-in solvent-free microwave-assisted synthesis of the corresponding coumarin derivatives has been investigated in detail.

Microwave atmospheric pressure plasma jets for wastewater treatment: Degradation of methylene blue as a model dye.

The degradation of methylene blue in aqueous solution as a model dye using a non thermal microwave (2.45 GHz) plasma jet at atmospheric pressure has been investigated. Argon has been used as feed gas and aqueous solutions with different concentrations of the dye were treated using the effluent from plasma jet in a remote exposure.

Raman microspectroscopic analysis of decorative pigments from the Roman villa of El Ruedo (Almedinilla, Spain).

In this work, we analysed the preparatory layer and paintings in the hypocaustum of the Roman villa of El Ruedo (Almedinilla, southern Spain). The specimens studied were from the III and IV centuries. Raman microscopy was for the first time used here to examine Roman pictures in the south of the Iberian peninsula.

Preparation of Palladium-Supported Periodic Mesoporous Organosilicas and their Use as Catalysts in the Suzuki Cross-Coupling Reaction.

Three periodic mesoporous materials, , two organosilicas with either ethylene or phenylene bridges and one silica, have been used as supports for Pd nanoparticles. All Pd-supported samples (1.0 wt%) were prepared by the incipient wetness method and subsequently reduced in an H₂ stream at 200 °C.

Metal-Exchanged β Zeolites as Catalysts for the Conversion of Acetone to Hydrocarbons.

Various metal-β zeolites have been synthesized under similar ion-exchange conditions. During the exchange process, the nature and acid strength of the used cations modified the composition and textural properties as well as the Brönsted and Lewis acidity of the final materials. Zeolites exchanged with divalent cations showed a clear decrease of their surface Brönsted acidity and an increase of their Lewis acidity.

Study of organo-hybrid layered double hydroxides by medium and near infrared spectroscopy.

An Mg/Al layered double hydroxide (LDH) containing carbonate ion in its interlayer region was examined by medium infrared (MIR) and near infrared reflectance spectroscopy (NIRS). The MIR and NIR spectroscopy techniques was also used to study two organo-hybrid LDHs containing interlayer dodecylbenzenesulphonate (DBS) and dodecylsulphate (DS) ions, respectively. The NIR spectra for the latter solids were found to exhibit the overtone and combination bands for the hydroxyl groups in addition to those typical bands of the organic host functions.

Formation of stable nanolayers of meixnerite via a combined delamination-ion exchange process.

A combination of delamination and ion exchange allowed us to obtain new solids consisting of nanolayers of double hydroxides containing hydroxyl as charge balancing ion (i.e., meixnerite monolayers).

Heterogeneous Suzuki cross-coupling reactions over palladium/hydrotalcite catalysts.

The efficiency of various heterogeneous solids consisting of palladium supported on hydrotalcite as catalysts in the Suzuki cross-coupling reaction between bromobenzene and phenylboronic acid was studied. Based on the catalytic activity results, the reaction develops to an acceptable extent with 100% selectivity at moderate temperatures in the presence of some of the catalysts. The best results were provided by a catalyst consisting of an acetate-pyridine complex of Pd supported on hydrotalcite that gave high conversion values even after three reuses.