Estrategias bottom-up para la síntesis de nanoarquitecturas porosas sobre soportes silícicos

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Geología y Geoquímica. Fecha de lectura: 12-02-201

The Imine-Based COF TpPa-1 as an Efficient Cooling Adsorbent That Can Be Regenerated by Heat or Light

Adsorption-based cooling systems, which can be driven by waste heat and solar energy, are promising alternatives to conventional, compression-based cooling systems, as they demand less energy and emit less CO. The performance of adsorption-based cooling systems relates directly to the performance of the working pairs (sorbent-water). Accordingly, improvement of these systems relies on the continual discovery of new sorbents that enable greater mass exchange while requiring less energy for regeneration. Here, it is proposed that covalent-organic frameworks (COFs) can replace traditional sorbents for adsorption-based cooling. In tests mimicking standard operating conditions for industry, the imine-based COF TpPa-1 exhibits a regeneration temperature below 65 °C and a cooling coefficient of performance of 0.77 - values which are comparable to those reported for the best metal-organic framework sorbents described to date. Moreover, TpPa-1 exhibits a photothermal effect and can be regenerated by visible light, thereby opening the possibility for its use in solar-driven cooling

A Self-Folding Polymer Film Based on Swelling Metal–Organic Frameworks

Herein, we exploit the well-known swelling behaviour of metal–organic frameworks (MOFs) to create a selffolding polymer film. Namely, we show that incorporating crystals of the flexible MOF MIL-88A into a polyvinylidene difluoride (PVDF) matrix affords a polymer composite film that undergoes reversible shape transformations upon exposure to polar solvents and vapours. Since the self-folding properties of this film correlate directly with the swelling properties of the MIL-88A crystals, it selectively bends to certain solvents and its degree of folding can be controlled by controlling the relative humidity. Moreover, it shows a shapememory effect at relative humidity values from 60% to 90%. As proof of concept, we demonstrate that these composite films can lift cargo and can be used to assemble 3D structures from 2D patterns. Our strategy is a straightforward method for designing autonomous soft materials with folding properties that can be tuned by judicious choice of the constituent flexible MOF.Proyecto del MINECO MAT2013-41836-R y de la Junta de Andalucía P12-FQM-165

Two-step synthesis of heterometallic coordination polymers using a polyazamacrocyclic linker

A new macrocyclic linker 1,4,7,10-tetraazacyclododecane-1,7-bis(4-acetamidobenzoic)-4,10-diacetic acid (HL1) was synthesized and characterized. This linker was used to create two heterometallic coordination polymers following a two-step synthesis. This synthesis consisted of first combining this polyazamacrocyclic linker with Ni(ii) or Mn(ii) ions to obtain the corresponding metallomacrocyclic complexes showing non-coordinated carboxylic groups. In a second step, these metallated macrocycles were used as building units to construct two heterometallic Ni(ii)-Zn(ii) and Mn(ii)-Zn(ii) coordination polymers when combined with Zn(ii) ions. In addition, a third Zn(ii)-Zn(ii) coordination polymer could also be synthesized by direct mixing of HL1 with Zn(ii) ions. Interestingly, the Mn(ii)-Zn(ii) coordination polymer exhibits a reversible type-I "crystal-to-amorphous transformation" upon water sorption/desorption

Nanoarchitectures Based on Layered Titanosilicates Supported on Glass Fibers: Application to Hydrogen Storage

This work reports on the synthesis of nanosheets of layered titanosilicate JDF-L1 supported on commercial E-type glass fibers with the aim of developing novel nanoarchitectures useful as robust and easy to handle hydrogen adsorbents. The preparation of those materials is carried out by hydrothermal reaction from the corresponding gel precursor in the presence of the glass support. Because of the basic character of the synthesis media, silica from the silicate-based glass fibers can be involved in the reaction, cementing its associated titanosilicate and giving rise to strong linkages on the support with the result of very stable heterostructures. The nanoarchitectures built up by this approach promote the growth and disposition of the titanosilicate nanosheets as a house-of-cards radially distributed around the fiber axis. Such an open arrangement represents suitable geometry for potential uses in adsorption and catalytic applications where the active surface has to be available. The content of the titanosilicate crystalline phase in the system represents about 12 wt %, and this percentage of the adsorbent fraction can achieve, at 298 K and 20 MPa, 0.14 wt % hydrogen adsorption with respect to the total mass of the system. Following postsynthesis treatments, small amounts of Pd (<0.1 wt %) have been incorporated into the resulting nanoarchitectures in order to improve their hydrogen adsorption capacity. In this way, Pd-layered titanosilicate supported on glass fibers has been tested as a hydrogen adsorbent at diverse pressures and temperatures, giving rise to values around 0.46 wt % at 298 K and 20 MPa. A mechanism of hydrogen spillover involving the titanosilicate framework and the Pd nanoparticules has been proposed to explain the high increase in the hydrogen uptake capacity after the incorporation of Pd into the nanoarchitecture.We thank the CICYT (Spain, projects MAT2009-09960 and MAT2012-31759), Obra Social la Caixa, Aragon Government (GA-LC-019/2011), ESF, Generalitat Valenciana, and FEDER (PROMETEO/2009/047) for financial support. J.P.-C. is grateful for a Ph.D. grant (FPI, BES-2010-038410) from the Spanish Ministerio de Ciencia e Innovación

Seguimiento clínico del ensayo de una vacuna VLP para los serotipos 1 y 1+4 de la lengua azul en ganado ovino

La Lengua azul es una enfermedad vírica sometida a un control sanitario compuesto por varias medidas de prevención, entre ellas la vacunación de las especies sensibles. En el desarrollo de vacunas frente a esta enfermedad, una nueva tendencia es la producción de vacunas polivalentes mediante la técnica de VLP (virus like particles). Este trabajo ha tenido como objetivo valorar mediante seguimiento clínico 2 vacunas VLP, frente al serotipo1 y frente a los serotipos 1+4. Los resultados confirman la falta de fiebre, sintomatología y lesiones anatomopatológicas en los animales vacunados frente a los controles, lo que indica que estas nuevas vacunas protegen frente a la aparición de sintomatología clínica.Bluetongue Virus disease is an infectous disease submitted to a sanitary control composed by several measures of prevention, and one of these measures is the vaccination of the sensible species. In the development of vaccines opposite to this disease, a new trend is the production of polyvalent vaccines by VLP's technology (virus like particles). This work has had as aim to value by clinical survey, 2 VLP vaccines, for serotypes 1 and 1+4. The results confirm the lack of fever, clinical signs and pathologic injuries in vaccinated animals opposite to control animals, which indicates that these new vaccines protect for the appearance of clinical signs

Assessment of the effect of nitrogen concentration on fermentation and selection of a highly competitive Saccharomyces cerevisiae strain for efficient ethanol production

The optimum nitrogen concentration for media supplementation and strain dominance are aspects of key importance to the industrial production of ethanol with a view to reducing costs and increasing yields. In this work, these two factors were investigated for four ethanologenic Saccharomyces cerevisiae strains (CLQCA-INT-001, CLQCA-INT-005, CLQCA-10-099, and UCLM 325), selected from the screening of 150 isolates, mostly from Ecuadorian yeast biodiversity. The effect of nitrogen concentration was assessed in terms of cellular growth, glucose consumption and ethanol production, and the yeast strains’ dominance was evaluated in continuous co-fermentation with cellular recycling by mitochondrial DNA analyses. Among the four selected yeast strains under study, CLQCA-INT-005 presented the highest glucose consumption at a nitrogen supplement concentration as low as 0.4 g·L−1, attaining an ethanol yield of up to 96.72% in 24 h. The same yeast strain was found to be highly competitive, showing a dominance of 80% after four cycles of fermentation in co-culture. Thus, CLQCA-INT-005 may be deemed as a very promising candidate to be used both at pilot-plant scale and at industrial scale cellulosic ethanol production

Metal Acetylacetonates as a Source of Metals for Aqueous Synthesis of Metal-Organic Frameworks

Demand continues for environmentally sound, high-yielding processes for the large-scale production of metal-organic frameworks (MOFs). Here we describe the use of metal acetylacetonate complexes as an alternative source of metals for the aqueous synthesis of MOFs. We have synthesized several carboxylate-based Zr(IV)-(UiO-66-NH2, Zr-fumarate, UiO-66-(OH)2, UiO-66-COOH and UiO-66-(COOH)2), Fe(III)-(MIL-88A) and Al(III)-(CAU-10) porous MOFs from their corresponding metal acetylacetonates in good yields (typically >85%) and, in some cases, at room temperature

Single-crystal and humidity-controlled powder diffraction study of the breathing effect in a metal-organic framework upon water adsorption/desorption

Herein we report a study on water adsorption/desorption-triggered single-crystal to single-crystal transformations in a MOF, by single-crystal and humidity-controlled powder X-ray diffraction and water-sorption measurements. We identified a gate-opening effect at a relative humidity of 85% upon water adsorption, and a gate-closure effect at a relative humidity of 55 to 77% upon water desorption. This reversible breathing effect between the "open" and the "closed" structures of the MOF involves the cleavage and formation of several coordination bonds

Composite Salt in Porous Metal-Organic Frameworks for Adsorption Heat Transformation

Adsorptive heat transformation systems such as adsorption thermal batteries and chillers can provide space heating and cooling in a more environmental friendly way. However, their use is still hindered by their relatively poor performances and large sizes due to the limited properties of solid adsorbents. Here, the spray-drying continuous-flow synthesis of a new type of solid adsorbents that results from combining metal-organic frameworks (MOFs), such as UiO-66, and hygroscopic salts, such as CaCl2 has been reported. These adsorbents, commonly named as composite salt in porous matrix (CSPM) materials, allow improving the water uptake capabilities of MOFs while preventing their dissolution in the water adsorbed; a common characteristic of these salts due to the deliquescence effect. It is anticipated that MOF-based CSPMs, in which the percentage of salt can be tuned, are promising candidates for thermal batteries and chillers. In these applications, it is showed that a CSPM made of UiO-66 and CaCl2 (38% w/w) exhibits a heat storage capacity of 367 kJ kg−1, whereas a second CSPM made of UiO-66 and CaCl2 (53% w/w) shows a specific cooling power of 631 W kg−1 and a coefficient of performance of 0.83, comparable to the best solid adsorbents reported so far