0000000000012522
AUTHOR
Jamal El Haskouri
Gold nanoparticles grown on a hydrophobic and texturally tunable PDMS-like framework
Mesoporous silicas are among the most suitable high-surface area solids to support small-sized metal clusters and nanoparticles. Unfortunately, the instability of silica in water constitutes a serious impediment for its widespread use and large implementation as a catalytic support for fine chemical synthesis and for biomass upgrading in the context of biorefineries. While end cupping silanols provides a way for delaying framework degradation, further investigations are needed to design more robust, water-resistant supports. Prompted by the success of polydimethylsiloxane (PDMS) in surface coating and water-repellent technologies, we herein explore the transformation of triethoxysilyl-funct…
Peptide-Capped Mesoporous Nanoparticles: Toward a more Efficient Internalization of Alendronate
[EN] Osteoporosis is an illness which appears when the osteoblast/osteoclast activities are unbalanced taking place bone resorption (caused by osteoclasts) in higher extension than bone formation (induced by osteoblasts). Alendronate is one of the most used drugs for osteoporosis treatment despite its scarce bioavailability. Here we present the synthesis and characterization of mesoporous gated nanoparticles (two sets) for the controlled release of alendronate. The first set of nanoparticles (S1) were loaded with sulforhodamine B and capped with a peptide that could be selectively hydrolyzed by cathepsin K enzyme (overexpressed in osteoclasts). The second set (S2) was functionalized with am…
Mesoporous iron phosphate/phosphonate hybrid materials
Abstract Relatively high surface area pure mesoporous iron-phosphorus oxide-based derivatives have been synthesized through an S + I − surfactant-assisted cooperative mechanism by means of a one-pot preparative procedure from aqueous solution and starting from iron atrane complexes and phosphoric and phosphonic acids. A soft chemical extraction procedure allows opening the pore system of the parent as-prepared materials by exchanging the surfactant without mesostructure collapse. The nature of the pore wall can be modulated from iron phosphate up to hybrids involving approximately 30% of organophosphorus entities (phosphonates or diphosphonates). X-ray powder diffraction, transmission elect…
Optical properties of exciton confinement in spherical ZnO quantum dots embedded in matrix
Abstract The optical characteristics of ZnO nanoparticles in SiO2 matrix have been determined by UV–visible and photoluminescence (PL) studies. The PL spectrum of the ZnO quantum dots shows two different bands: the first one is a broad green emission band related to deep level emission in the visible range and the second one is situated at 3.48 eV in the ultraviolet region, and is attributed to the recombination of electrons in the conduction band and holes in the valence band. The experimental result that we found was simulated numerically using different methods. Our calculations revealed a good agreement between the matrix element calculation method and the experimental result. We have a…
Chromogenic Chemodosimeter Based on Capped Silica Particles to Detect Spermine and Spermidine
A new hybrid organic–inorganic material for sensing spermine (Spm) and spermidine (Spd) has been prepared and characterized. The material is based on MCM-41 particles functionalized with an N-hydroxysuccinimide derivative and loaded with Rhodamine 6G. The cargo is kept inside the porous material due to the formation of a double layer of organic matter. The inner layer is covalently bound to the silica particles, while the external layer is formed through hydrogen and hydrophobic interactions. The limits of detection determined by fluorimetric titration are 27 µM and 45 µM for Spm and Spd, respectively. The sensor remains silent in the presence of other biologically important amines and is a…
Precatalyst or dosing-device? The [Pd2{μ-(C6H4) PPh2}2{μ-O2C(C6H5)}2] complex anchored on a carboxypolystyrene polymer as an effective supplier of palladium catalytically active nanoparticles for the Suzuki-Miyaura reaction
Abstract A new catalyst has been synthesized from the precursor [Pd2{μ-(C6H4) PPh2}2 {μ-O2C(C6H5)}2] immobilized on a carboxypolystyrene polymer that exhibits an excellent dispersion of the Pd (II) centers, reusability, and catalytic activity in front of phenyl bromides. The activity of this new material was studied in detail for the Suzuki-Miyaura reaction and compared to that of Pd nanoparticles (NPs) supported on UVM-7 (a mesoporous silica), and Pd NPs stabilized with polyvinylpirrolydone. The homogeneous/heterogeneous character of the catalytic process was determined from the results of the hot-filtration, centrifugation, poisoning, three phases tests, and from differential sensitivity …
ZnO nanoparticles embedded in UVM-7-like mesoporous silica materials: Synthesis and characterization
Abstract ZnO nanodomains embedded in bimodal mesoporous silica (UVM-7) materials with high Zn content (4≤Si/Zn≤30) have been synthesized by an one-pot surfactant-assisted procedure from a hydro alcoholic medium using a cationic surfactant (CTMABr=cetyltrimethylammonium bromide) as structural directing agent, and starting from molecular atrane complexes of Zn and Si as hydrolytic inorganic precursors. This chemical procedure allows optimizing the dispersion of the ZnO particles in the silica walls. The bimodal mesoporous nature of the final high surface area nano-sized materials is confirmed by XRD, TEM, and N2 adsorption–desorption isotherms. The small intra-particle mesopore system is due …
Energy of excitons and acceptor–exciton complexes to explain the origin of ultraviolet photoluminescence in ZnO quantum dots embedded in a SiO2 matrix
Abstract Assuming finite depth and within the effective mass approximation, the energies of exciton states and of the acceptor–exciton complexes confined in spherical ZnO quantum dots (QDs) embedded in a SiO2 matrix are calculated using a matrix procedure, including a three-dimensional confinement of carrier in the QDs. This theoretical model has been designed to illustrate the two emission bands in the UV region observed in our experimental Photoluminescence spectrum (PL), with the first emission band observed at 3.04 eV and attributed to the bound ionized acceptor–exciton complexes, and the second one located at 3.5 and assigned to the free exciton. Our calculations have revealed a good a…
Phosphorylated micro- vs. nano-cellulose: a comparative study on their surface functionalisation, growth of titanium-oxo-phosphate clusters and removal of chemical pollutants
Controlled cellulose disassembly affords many variants including amorphous micro-sized cellulose crystals (MCC) and cellulose nano-sized crystals (CNC), which have emerged recently as green and sustainable nanomaterials. Unfortunately, their lower reactivity and thermal and chemical instability constitute an impediment for multifaceted nanoscience and nanotechnology usage. Herein, MCC and CNC are functionalised using two phosphorus derivatives (phosphoryl chloride and hexachlorocyclotriphosphazene), under acid-free, urea-free and corrosive-free, gentle experimental conditions. Notably, CNC can accommodate more phosphorus species compared to MCC, with the bulky phosphazene precursor being le…
Highly Active Hydrogenation Catalysts Based on Pd Nanoparticles Dispersed along Hierarchical Porous Silica Covered with Polydopamine as Interfacial Glue
New catalysts based on Pd(0) nanoparticles (Pd NPs) on a bimodal porous silica of the UVM-7/polydopamine (PDA) support have been synthesized following two preparative strategies based on the sequential or joint incorporation of two components of the composite (Pd and PDA). We analyzed the role played by the PDA as &lsquo
Phosphorylation triggered growth of metal phosphate on halloysite and sepiolite nanoparticles: preparation, entrapment in chitosan hydrogels and application as recyclable scavengers
The rational design of porous, biomass-derived eco-friendly adsorbents instead of costly synthetic, petroleum-based resins stands as a promising approach to resolving the thorny issue of sewage treatment (for example, by supplying safe water for drinking and irrigation). Herein we explore a straightforward transformation of abundant clay and polysaccharides into highly-reactive water-cleaning adsorbents. Surface-functionalization of sepiolite and halloysite by phosphoryl chloride triggered metal dissolution from the framework (inside of the lumen for halloysite and on the external surface for sepiolite) and the concomitant growth of well-truncated crystalline metal phosphates. These unprece…
Very high titanium content mesoporous silicas
Titanium content in mesoporous titanosilicate catalysts has been modulated up to a minimum Si/Ti value of 1.9 by using complexing agents able to coordinate both Si and Ti atoms and harmonize the reactivity of the resulting precursors avoiding subsequent phase segregation and leading to chemically very homogeneous materials. El Haskouri, Jamal, Jamal.Haskouri@uv.es ; Beltran Porter, Aurelio, Aurelio.Beltran@uv.es ; Beltran Porter, Daniel, Daniel.Beltran@uv.es ; Amoros del Toro, Pedro Jose, Pedro.Amoros@uv.es
Silica-based powders and monoliths with bimodal pore systems
Porous pure and doped silicas with pore sizes at two length scales (meso/macroporous) have been prepared and shaped both as powders and monoliths through a one-pot surfactant assisted procedure by using a simple template agent and starting from atrane complexes as inorganic precursors. El Haskouri, Jamal, Jamal.Haskouri@uv.es ; Latorre Saborit, Julio, Julio.Latorre@uv.es ; Beltran Porter, Aurelio, Aurelio.Beltran@uv.es ; Beltran Porter, Daniel, Daniel.Beltran@uv.es ; Amoros del Toro, Pedro Jose, Pedro.Amoros@uv.es
AlTf-UVM-7—Highly active catalysts for the synthesis of long chain symmetrical ethers and non-ionic surfactant structures
New Lewis acid AlTf-UVM-7 catalysts with bimodal pore system and different Si to Al ratios were prepared in a two-step synthesis in which triflic acid (Tf) was incorporated into previously synthesized mesoporous aluminum-containing silica. The Al incorporation inside the pore walls was carried out through the Atrane method. The characterization of the resulted catalysts showed that the triflic acid treatment step did not damage the texture or the structure of the catalysts. These materials were used as green catalysts for the etherification of fatty alcohols and the conversion of ethylene glycol (EG) with n-octanol resulting in mixtures of short ethoxylated structures with a large distribut…
Improving epoxide production using Ti-UVM-7 porous nanosized catalysts
Nanosized Ti-UVM-7 materials with a hierarchical system of pores at two different length scales have been prepared through a one-pot procedure by using a simple template agent; the catalytic activity and selectivity of the resulting materials in bulky olefin epoxidation by organic peroxides are the highest reported to date.
Mesoporous aluminum phosphite
Abstract High surface area pure mesoporous aluminum-phosphorus oxide-based derivatives have been synthesized through an S+I− surfactant-assisted cooperative mechanism by means of a one-pot preparative procedure from aqueous solution and starting from aluminum atrane complexes and phosphoric and/or phosphorous acids. A soft chemical extraction procedure allows opening the pore system of the parent as-prepared materials by exchanging the surfactant without mesostructure collapse. The nature of the pore wall can be modulated from mesoporous aluminum phosphate (ALPO) up to total incorporation of phosphite entities (mesoporous aluminum phosphite), which results in a gradual evolution of the acid…
Nanoparticulated Silicas with Bimodal Porosity: Chemical Control of the Pore Sizes
Nanoparticulated bimodal porous silicas (NBSs) with pore systems structured at two length scales (meso- and large-meso-/macropores) have been prepared through a one-pot surfactant-assisted procedure by using a simple template agent and starting from silicon atrane complexes as hydrolytic inorganic precursors. The final bulk materials are constructed by an aggregation of pseudospherical mesoporous primary nanoparticles process, over the course of which the interparticle (textural) large pore system is generated. A fine-tuning of the procedural variables allows not only an adjustment of the processes of nucleation and growth of the primary nanoparticles but also a modulation of their subseque…
Enhancing extraction performance of organophosphorus flame retardants in water samples using titanium hierarchical porous silica materials as sorbents.
Abstract A sorbent for the extraction of organophosphorus flame retardants has been proposed, based on UVM-7 (University of Valencia Materials) mesoporous silica doped with titanium. Designed cartridges have been applied to the extraction and preconcentration of flame retardants in water samples, followed by gas chromatography coupled to a mass spectrometry detector. Firstly, UVM-7 materials with different contents of titanium were synthesized and characterized by several techniques, thus confirming the proper mesoporous architecture. The potential of these materials was assessed in comparison with their morphological properties, resulting Ti50-UVM-7 the best solid phase. Several extraction…
A new method for fluoride determination by using fluorophores and dyes anchored onto MCM-41Electronic supplementary information (ESI) available: IR spectra, SEM images, X-ray diffraction patterns and TG/TD analysis. See http://www.rsc.org/suppdata/cc/b1/b111128k/
A new colourimetric and fluorimetric method for fluoride determination in aqueous samples based on the specific reaction between fluoride and silica has been developed and applied on real samples.
Nitroarene hydrogenation catalysts based on Pd nanoparticles glued with PDA on inorganic supports: Multivariate Curve Resolution as an useful tool to compare the catalytic activity in multi-step reactions
[EN] Two green catalysts based on Pd(0) nanoparticles (Pd NPs) anchored through PDA on porous silica and magnetite have been synthesized using a generalized simple and reproducible "two-step" methodology. Both catalysts were tested for a model reaction, the hydrogenation of 4-nitrophenol using NaBH4 as the hydrogenating agent, and especially good activity has been achieved in the case of the catalysts containing magnetite as inorganic core (Pd NPs-PDA@Fe3O4). We analyzed the effect associated with the catalyst separation method (centrifugation or magnetically) that affect to the distribution and aggregation degree of the Pd NPs. In addition, we also correlate the final catalyst morphology w…
ChemInform Abstract: Enhanced Surface Area in Thermally Stable Pure Mesoporous TiO2.
Abstract We describe here for the first time the surfactant-assisted synthesis of thermally stable mesoporous pure TiO 2 having a high surface area. Our synthetic approach to the chemistry of this system is based on the equilibrium between the hydrolysis and condensation reactions of the inorganic species and the organic–inorganic self-assembling processes. The use of titanatrane complexes helps to retard the hydrolysis and condensation reactions, thus allowing us to overcome the difficulties in preparing titanium dioxide mesoporous materials starting from highly reactive Ti-alkoxides. The mesoporous material has been characterized by TEM, XRD and N 2 adsorption–desorption isotherms and dis…
Interface charge density matching as driving force for new mesostructured oxovanadium phosphates with hexagonal structure, [CTA]xVOPO4·zH2O
Hexagonal mesostructured mixed-valence oxovanadium phosphates [CTA]xVOPO4·zH2O, in short ICMUV-2, have been synthesized through a S+I- cooperative mechanism using cationic surfactant (cetyltrimethylammonium, CTAB) rodlike micelles as a template. On the lines of the hypothesis that the driving force leading to the formation of mesostructured solids is the charge density matching at the interface between the supramolecular−organic and supramolecular−inorganic moieties, the self-assembling process between CTA+ micelles and VOPO4q- planar anions can be thought of as consequence of the adequate adjustment of the metal mean oxidation state. X-ray powder diffraction and TEM techniques show that th…
A new efficient, highly dispersed, Pd nanoparticulate silica supported catalyst synthesized from an organometallic precursor. Study of the homogeneous vs. heterogeneous activity in the Suzuki-Miyaura reaction
[EN] A new Pd(0) catalyst supported on silica UVM-7 has been synthesized from the organometallic [Pd-2(mu-(C6H4) Pp(2))(2)(CH3CN)(4)](BF4)(2) precursor, characterized by the high dispersion, activity, and small size of the palladium nanoclusters fixed on the silica surface. The catalyst was tested for the Suzuki-Miyaura (SM) reaction of different 4-substitutedphenyl halides with phenylboronic acid. The kinetic study concurs with most of the catalytic action was carried out by Pd species originated by the partial solubilization of Pd immobilized on mesoporous silica. The Schmidt's analysis of differential selectivity (SADS) in several competitive SM reactions, together the STEM-HAADF and HRT…
Enhanced surface area in thermally stable pure mesoporous TiO2
Abstract We describe here for the first time the surfactant-assisted synthesis of thermally stable mesoporous pure TiO 2 having a high surface area. Our synthetic approach to the chemistry of this system is based on the equilibrium between the hydrolysis and condensation reactions of the inorganic species and the organic–inorganic self-assembling processes. The use of titanatrane complexes helps to retard the hydrolysis and condensation reactions, thus allowing us to overcome the difficulties in preparing titanium dioxide mesoporous materials starting from highly reactive Ti-alkoxides. The mesoporous material has been characterized by TEM, XRD and N 2 adsorption–desorption isotherms and dis…
Use of Silica Based Materials as Modulators of the Lipase Catalyzed Hydrolysis of Fats under Simulated Duodenal Conditions
[EN] The effect of silica materials and their functionalization in the lipase catalyzed fat hydrolysis has been scarcely studied. Fifteen silica materials were prepared and their effect on the fat hydrolysis was measured, under simulated duodenal conditions, using the pH-stat method. The materials are composed of the combination of three supports (Stober massive silica nanoparticles, Stober mesoporous nanoparticles and UVM-7) and four surface functionalizations (methyl, trimethyl, propyl and octyl). In addition, the non-functionalized materials were tested. The functional groups were selected to offer a hydrophobic character to the material improving the interaction with the fat globules an…
The First Pure Mesoporous Aluminium Phosphonates and Diphosphonates − New Hybrid Porous Materials
Organophosphorus moieties have been incorporated into mesoporous ALPOs through a one-pot surfactant-assisted procedure leading, for the first time, to periodic mesoporous aluminium phosphonates and diphosphonates. The number of organic groups on the surface or in the network can be modulated continuously up to the maximum incorporation level of the respective organophosphorus entities (100 %). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
New heterogeneous catalysts for greener routes in the synthesis of fine chemicals
Abstract New strong Lewis acid SnTf-MCM-41 and SnTf-UVM-7 catalysts with unimodal and bimodal pore systems were prepared in a two-step synthesis in which the triflic acid (Tf) was incorporated to previously synthesized mesoporous tin-containing silicas. The Sn incorporation inside the pore walls was carried out through the Atrane method. The SnTf-UVM-7 catalysts were prepared by aggregating nanometric mesoporous particles defining a hierarchic textural-type additional pore system. Following these procedures, catalysts with different Si/Sn ratios—21.8 to 50.8 for SnTf-MCM-41 and 18.4 for SnTf-UVM-7—were prepared. These new materials were tested in the acylation of aromatic sulfonamides using…
Layered-Expanded Mesostructured Silicas: Generalized Synthesis and Functionalization
Mesostructured layered silicas have been prepared through a surfactant-assisted procedure using neutral alkylamines as templates and starting from atrane complexes as hydrolytic inorganic precursors. By adjusting the synthetic parameters, this kinetically controlled reproducible one-pot method allows for obtaining both pure and functionalized (inorganic or organically) lamellar silica frameworks. These are easily deconstructed and built up again, which provides a simple way for expanding the interlamellar space. The materials present high dispersibility, which results in stable colloidal suspensions.
Surfactant-Assisted Synthesis of Mesoporous Alumina Showing Continuously Adjustable Pore Sizes
Porous materials displaying tailor-made pore sizes and shapes are particularly interesting in a great variety of real and potential applications where molecular recognition is needed, such as shape-selective catalysis, molecular sieving, and selective adsorption. Classically, apart from silica, materials most commonly used for catalysis and catalyst supports have been those based on high surface aluminas, owing to their thermal, chemical, and mechanical stability and their low cost. Earlier aluminas with high surface areas (~500 m/g) had been prepared using structure-directing agents. However, they were X-ray amorphous materials and their porosity was purely textural, characterized by wide …
Towards the Loewenstein limit (Si/Al = 1) in thermally stable mesoporous aluminosilicates
The use of complexing agents to generate polynuclear precursor species containing both Al and Si allows the synthesis of thermally stable mesoporous aluminosilicates including solely tetrahedrally coordinated aluminium, in which the Si/Al ratio can be modulated down to a minimum Si/Al value of 1.06(4). Cabrera Medina, Saul, Saul.Cabrera@uv.es ; El Haskouri, Jamal, Jamal.Haskouri@uv.es ; Latorre Saborit, Julio, Julio.Latorre@uv.es ; Beltran Porter, Aurelio, Aurelio.Beltran@uv.es ; Beltran Porter, Daniel, Daniel.Beltran@uv.es ; Amoros del Toro, Pedro Jose, Pedro.Amoros@uv.es
Stable anchoring of dispersed gold nanoparticles on hierarchic porous silica-based materials
The nanometric organization of MOx (M = Co, Zn, Ni) domains partially embedded inside the mesoporous silica walls but accessible to the pore voids, which is achieved through a simple one-pot surfactant-assisted procedure, define optimal anchors for the nucleation and growth of gold nanoparticles, which in turn favours an exceptional thermal stability for the final Au-supported materials. As silica support we have selected a UVM-7 silica having a highly accessible architecture defined by two hierarchic pore systems. The combination of nanometric pore length, tortuous mesopores and MOx inorganic anchors favours the stability of the final Au/CoOx-UVM-7 nanocomposites.
Silica-based powders and monoliths with bimodal pore systemsElectronic supplementary information (ESI) available: UV–Vis spectrum of sample 3. See http://www.rsc.org/suppdata/cc/b1/b110883b/
Porous pure and doped silicas with pore sizes at two length scales (meso/macroporous) have been prepared and shaped both as powders and monoliths through a one-pot surfactant assisted procedure by using a simple template agent and starting from atrane complexes as inorganic precursors.
Efficient Sc triflate mesoporous-based catalysts for the synthesis of 4,4′-methylenedianiline from aniline and 4-aminobenzylalcohol
Abstract Sc triflate mesoporous-based catalysts have been prepared using a two-step strategy (i.e., Atrane method) based on the formation of the hierarchic bimodal porosity in the first step and the formation of Sc triflate complexes at the materials surface in the second step. All solids were analyzed by EPMA, surface area, and pore size values, XRD, TEM, FTIR, and 45Sc NMR static spectra. The catalysts have been investigated in the synthesis of 4,4′-methylenedianiline (4,4′-MDA) from aniline and 4-aminobenzylalcohol. 4,4′-MDA was obtained with selectivities over 85.0% for a conversion of aniline of 31%, at 80 °C and after 24 h. Using microwaves, selectivities of 90% in 4,4′-MDA were reach…
High content and dispersion of Gd in bimodal porous silica: T2 contrast agents under ultra-high magnetic fields
Silica-based UVM-7-type bimodal mesoporous materials with high gadolinium content (∞ ≥ Si/Gd ≥ 13) have been synthesized through a one-pot surfactant-assisted procedure from hydroalcoholic solution using a cationic surfactant as template, and starting from atrane complexes of Gd and Si as inorganic precursors. The novel synthetic pathway developed in the study preserves the UVM-7-type architecture while optimizing the dispersion of the Gd-guest species at the nanoscale and even at atomic level. It has been determined that the number of Gd atoms forming clusters is always less than 10. The behaviour under exposure to ultra-high magnetic fields reveals a significant increase in the transversa…
Comparison of silica-based materials for organophosphorus pesticides sampling and occupational risk assessment.
Abstract A novel air sampler has been designed containing a sorbent based on UVM-7 mesoporous silica doped with Ti. The sorbent has been applied for the determination of organophosphorus pesticides in occupational air, followed by gas chromatography with mass spectrometry detection. Thus, several silica materials with different structures (mesoporous UVM-7 and microporous xerogels) were synthesized, and modified with the addition of Ti and Fe. The structure of these materials was proved by transmission electronic microscopy, energy-dispersive X-ray, X-ray diffraction, nitrogen adsorption-desorption and UV–Vis and Raman spectroscopy. The potential of these materials for the retention of pest…
One‐Pot Synthesis of Superparamagnetic CoO‐MCM‐41 Nanocomposites with Uniform and Highly Dispersed Magnetic Nanoclusters
Superparamagnetic CoO-MCM-41 mesoporous nanocomposites, with variable cobalt amounts, in the form of well-dispersed CoO-like clusters, were prepared in a large compositional range by a one-step reproducible procedure employing co-hydrolysis and co-condensation of the inorganic precursors in a water/triethanolamine medium. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Mesoporous silica microparticles gated with a bulky azo derivative for the controlled release of dyes/drugs in colon.
[EN] Mesoporous silica microparticles were prepared, loaded with the dye safranin O (M-Saf) or with the drug budesonide (M-Bud) and capped by the grafting of a bulky azo derivative. Cargo release from M-Saf at different pH values (mimicking those found in the gastrointestinal tract) in the absence or presence of sodium dithionite (a reducing agent mimicking azoreductase enzyme present in the colon) was tested. Negligible safranin O release was observed at pH 6.8 and 4.5, whereas a moderate delivery at pH 1.2 was noted and attributed to the hydrolysis of the urea bond that linked the azo derivative onto the external surface of the inorganic scaffold. Moreover, a marked release was observed w…
Design, characterization and comparison of materials based on β and γ cyclodextrin covalently connected to microporous silica for environmental analysis
Abstract Determination of organic pollutants in environmental samples presents great difficulties due to the lack of sensitivity and selectivity in many of the existing analytical methods. In this work, the efficiency of materials based on silica structures containing bounded γ-cyclodextrin has been evaluated to determinate phenolic compounds and polycyclic aromatic hydrocarbons in air and water samples, respectively, in comparison with materials made of β-cyclodextrin. According to the results obtained for the material characterization, the new γ-cyclodextrin solid phase does not apparently present any porosity when used in air samples, but it has been shown to work efficiently for the pre…
Synthesis, characterization and catalytic behavior of AlTf/UVM-7 as new green catalysts for the glycols etherification reactions
Abstract Bimodal porous Al–UVM-7 system materials with different Si-to-Al ratios were prepared using the Atrane route. These were converted in strong acid heterogeneous AlTf-based catalysts after the treatment with methanolic solutions of triflic acid. The materials so obtained were used as catalysts for the conversion of ethylene glycol (EG) and propylene glycol (PG) with octanol under solvent-free conditions. The process is selective to short ethoxylated structures resulting in the corresponding monoethers. While the conversion of EG and PG was very high (>94%) irrespective of the support characteristics, 1-octanol was transformed only in low degree (3–35%), and its conversion depends on …
Combination of silica nanoparticles with hydroxyapatite reinforces poly (l-lactide acid) scaffolds without loss of bioactivity
Composite scaffolds of poly(l-lactide acid) and hydroxyapatite are of great interest in bone tissue engineering, but their mechanical properties are typically inferior to scaffolds of pure poly(l-lactide acid) due to agglomeration of the particles and weak interfacial component interaction. Fabrication strategies like double sonication of hydroxyapatite or increasing the amount of this inorganic filler do not effectively enhance the mechanical performance. In this study, poly(l-lactide acid) composites combining two types of fillers, mesoporous silica (SiO2) nanoparticles and hydroxyapatite, were developed to reinforce the poly(l-lactide acid) scaffold without any loss of bioactivity. A 5%…
Control of the pore wall thickness and thermal stability in low-cost bimodal porous silicas
Abstract A new hierarchical bimodal mesoporous silica, labelled as UVM-12 (acronym of University of Valencia Materials), has been prepared by using a solution of sodium silicate as low-cost silicon source. The final self-assembling between cationic micelles of CTAB and anionic inorganic Si-based oligomers occurs in a homogeneous aqueous medium. The reaction is carried out from low-sized building blocks through a bottom-up approach. The UVM-12 solids combine two mesopore systems according to N2 adsorption–desorption isotherms, what is corroborated by TEM micrographs and XRD patterns. This material has been inorganically modified by incorporation of Al or Ti (M-UVM-12, M = Al, Ti) without alt…
A review on LiNixCo1−2xMnxO2 (0.1 ≤ x ≤ 0.33) cathode materials for rechargeable Li-ion batteries
Abstract Electrochemical and physical properties of LiNixCo1−2xMnxO2 (0.1 ≤ x ≤ 0.33) electrode materials prepared by self-combustion were investigated. Pure LiNixCo1−2xMnxO2 (x = 0.1, 0.2, 0.33) materials with single phase and R-3 m layered structure were obtained as confirmed by X-ray diffraction. Energy Dispersive Spectroscopy, Scanning Electron Microscopy are commonly used to determine the chemical composition and the distribution of particle size of the three samples. The electrochemical performances of the samples were measured at different current rates in the 3–4.5 V potential range. The studied materials exhibit good discharge capacity. The magnetic susceptibility measurements and …
Biomimetic chitosan-mediated synthesis in heterogeneous phase of bulk and mesoporous silica nanoparticles
Both bulk and mesoporous silica nanoparticles can be obtained in the form of granular aggregates using chitosan flakes as additive under very soft biomimetic reaction conditions. Puchol Estors, Victoria, Victoria.Puchol@uv.es ; El Haskouri, Jamal, Jamal.Haskouri@uv.es ; Latorre Saborit, Julio, Julio.Latorre@uv.es ; Beltran Porter, Aurelio, Aurelio.Beltran@uv.es ; Beltran Porter, Daniel, Daniel.Beltran@uv.es ; Amoros del Toro, Pedro Jose, Pedro.Amoros@uv.es
Tuning the pore size from micro- to meso-porous in thermally stable aluminophosphates
Thermally stable porous aluminophosphates (ICMUV-3) with P/Al molar ratios in the range 0.15 <= P/Al <= 0.75 and showing continuously adjustable pore sizes from 13 to 37 Å have been prepared through a surfactant-assisted procedure without changing the surfactant length and/or addition of organic expansors. Cabrera Medina, Saul, Saul.Cabrera@uv.es ; El Haskouri, Jamal, Jamal.Haskouri@uv.es ; Beltran Porter, Aurelio, Aurelio.Beltran@uv.es ; Beltran Porter, Daniel, Daniel.Beltran@uv.es ; Amoros del Toro, Pedro Jose, Pedro.Amoros@uv.es
Supplementary Material from Mesoporous silica microparticles gated with a bulky azo derivative for the controlled release of dyes/drugs in colon
Mesoporous silica microparticles were prepared, loaded with the dye safranin O (M-Saf) or with the drug budesonide (M-Bud) and capped by the grafting of a bulky azo derivative. Cargo release from M-Saf at different pH values (mimicking those found in the gastrointestinal tract (GIT)) in the absence or presence of sodium dithionite (a reducing agent mimicking azoreductase enzyme present in the colon) was tested. Negligible safranin O release was observed at pH 6.8 and 4.5, whereas a moderate delivery at pH 1.2 was noted and attributed to the hydrolysis of the urea bond that linked the azo derivative onto the external surface of the inorganic scaffold. Moreover, a marked release was observed …
Generalised syntheses of ordered mesoporous oxides: the atrane route
Abstract A new simple and versatile technique to obtain mesoporous oxides is presented. While implying surfactant-assisted formation of mesostructured intermediates, the original chemical contribution of this approach lies in the use of atrane complexes as precursors. Without prejudice to their inherent unstability in aqueous solution, the atranes show a marked inertness towards hydrolysis. Bringing kinetic factors into play, it becomes possible to control the processes involved in the formation of the surfactant–inorganic phase composite micelles, which constitute the elemental building blocks of the mesostructures. Independent of the starting compositional complexity, both the mesostructu…
Synthesis of a new mesostructured lamellar oxovanadium phosphate assembled through an S+X-I0 Mechanism
A new lamellar mesostructured oxovanadium(V) phosphate, (DDAH)0.9(Cl)0.9VOPO4·1.5H2O (DDA = dodecylamine), has been synthesized through a S+X-I0 cooperative mechanism using protonated dodecylamine ...
Atrane complexes chemistry as a tool for obtaining trimodal UVM-7-like porous silica
[EN] The use of atrane complexes as hydrolytic precursors enables the homogeneous incorporation of manganese (25Si/Mn48) throughout the porous walls of the nanoparticles of a surfactant-templated bimodal mesoporous silica (UVM-7). The subsequent leaching of the manganese nanodomains allows adding controlled microporosity to the host silica framework. The resulting final silica material presents three pore systems structured at different length scales: interparticle textural-type macroporosity (ca. 43.2nm), ordered intraparticle mesoporosity (ca. 2.63nm; after template removal), and well-dispersed microporosity (< 2nm; as consequence of the lixiviation of the Mn-rich domains). The good dispe…
Mesosynthesis of ZnO-SiO(2) porous nanocomposites with low-defect ZnO nanometric domains.
Silica-based ZnO-MCM-41 mesoporous nanocomposites with high Zn content (5≤Si/Zn≤50) have been synthesized by a one-pot surfactant-assisted procedure from aqueous solution using a cationic surfactant (CTMABr = cetyltrimethylammonium bromide) as structure-directing agent, and starting from molecular atrane complexes as inorganic hydrolytic precursors. This preparative technique allows optimization of the dispersion of the ZnO nanodomains in the silica walls. The mesoporous nature of the final materials is confirmed by x-ray diffraction (XRD), transmission electron microscopy (TEM) and N(2) adsorption-desorption isotherms. The ZnO-MCM-41 materials show unimodal pore size distributions without …
Not always what closes best opens better: mesoporous nanoparticles capped with organic gates
ABSTRACT Four types of calcined MCM-41 silica nanoparticles, loaded with dyes and capped with different gating ensembles are prepared and characterized. N1 and N2 nanoparticles are loaded with rhodamine 6G and capped with bulky poly(ethylene glycol) derivatives bearing ester groups (1 and 2). N3-N4 nanoparticles are loaded with sulforhodamine B and capped with self-immolative derivatives bearing ester moieties. In the absence of esterase enzyme negligible cargo release from N1, N3 and N4 nanoparticles is observed whereas a remarkable release for N2 is obtained most likely due to the formation of an irregular coating on the outer surface of the nanoparticles. In contrast, a marked delivery i…
Generalized “one-pot” preparative strategy to obtain highly functionalized silica-based mesoporous spherical particles
In this work we present a synthesis strategy for the preparation of Stöber-type mesoporous particles functionalized with inorganic species. The procedure is based on a combination of the Atrane and the Stöber methods. Both as a source of silicon and of the incorporated heteroelements (Fe, Zn, Al, Ti) the corresponding atrane complexes are used as hydrolytic reagents. These complexes are easily formed by reaction with triethanolamine. Mesoporosity is achieved using surfactant micelles as templates. Obtaining uniform spherical particles is achieved by optimizing the amount of water-ethanol in the reaction medium. The particle sizes have been modulated by controlling simple parameters such as …
A Mesoporous 3D Hybrid Material with Dual Functionality for Hg2+Detection and Adsorption
Dual-function hybrid material U1 was designed for simultaneous chromofluorogenic detection and removal of Hg(2+) in an aqueous environment. Mesoporous material UVM-7 (MCM41 type) with homogeneously distributed pores of about 2-3 nm in size, a large specific surface area exceeding 1000 m(2) g(-1), and nanoscale particles was used as an inorganic support. The mesoporous solid is decorated with thiol groups that were treated with squaraine dye III to give a 2,4-bis(4-dialkylaminophenyl)-3-hydroxy-4-alkylsulfanylcyclobut-2-enone (APC) derivative that is covalently anchored to the inorganic silica matrix. The solid was characterised by various techniques including X-ray diffraction, transmission…
Low-Cost Synthesis of Bimodal Mesoporous Silica-Based Materials by Pseudomorphic Transformation.
Nanoparticulate bimodal porous silica-based materials have been prepared through a surfactant-assisted procedure by using a simple template and starting from inexpensive sodium silicate as silicon source. Different procedural variables, such as pH or the nature and concentration of the surfactant, have been explored to optimize the preparative protocol, which allows, in turn, improved understanding of the formation process. The final bulk materials (called UVM-10 or M-UVM-10) are formed by pseudomorphic transformation of fresh silica-based xerogels under mild basic conditions. The UVM-10 architecture is constructed from small mesoporous nanoparticles, the aggregation of which generates a di…
Study of silica-structured materials as sorbents for organophosphorus pesticides determination in environmental water samples
Abstract A novel sorbent based on a UVM-7 mesoporous silica doped with Ti has been synthesized and used for solid-phase extraction of several organophosphorus pesticides in environmental water samples followed by gas chromatography coupled to a nitrogen-phosphorus selective detector. Thus, mesoporous silica materials doped with Ti and Fe as well as immobilized cyclodextrin silica-based supports were prepared and morphologically characterized by several techniques such as transmission electronic microscopy, nitrogen adsorption-desorption and X-ray diffraction. These sorbents were comparatively evaluated, and Ti25-UVM-7 material was selected as the best solid phase. After optimization of extr…