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Soft crystallization routes for the controlled growth of oneand two-dimensional Cu(II)-coordination polymers of the type [(Cu- (hfa)2)x(3-tpt)]n (hfa = hexafluoroacetylacetonate, 3-tpt = 2,4,6-tris(3- pyridyl)-1,3,5-triazine) are described. Three volatile solvents with different protic/aprotic characteristics were chosen as the reaction media, e.g., supercritical CO2, chloroform, and ethanol. Five (1−5) new compounds were crystallized, with different structures and Cu(II)/3-tpt ratios. The structures of 3-tpt and five new coordination polymers were elucidated by single-crystal synchrotron X-ray diffraction. A description of the crystallization pathways followed for the synthesis of the individual compounds is given based on the protic or aprotic character of the used solvents and reagents’ solubility constraints. The main novelty of the work relies in establishing the foundations of 3-tpt isomeric control during crystallization through solvent selection. From the five precipitated new compounds, 3 displays a significant framework flexibility, associated with N2 adsorption at low temperature, presenting a stepwise adsorption isotherm. The N2 adsorption process was followed by in situ synchrotron X-ray powder diffraction, This work was financed by the Spanish National Plan of Research with project CTQ2017-83632. C.D., J.G.P., A.B., N.P.-G., J.F., and A.M.L.-P. acknowledge the financial support from the Spanish MEC, through the Severo Ochoa Program for Centres of Excellence in R&D (SEV-2015-0496). This work (N.P.-G., A.B., and J.F.) has been done in the framework of the doctoral program “Chemistry” of the Universitat Autonoma de Barcelona. A.M.L.-P. acknowledges the RyC- ̀ 2012-11588 contract. N.P.-G. and A.B. acknowledge FPI grants. ALBA synchrotron is acknowledged for the provision of beam time.

Supercritical CO2 (scCO2) technology is used here as an efficient method to assist in the preparation of a cutaneous polymeric formulation based on drug containing metal-organic framework composites. The supercritical fluid is used in three steps: (i) as a drying agent for the nanosized mesoporous matrix, (ii) as the impregnation vector of a topical antibiotic drug, and (iii) as a plasticizing and foaming fluid to obtain dispersions of the hybrid material into a biocompatible polymer, e.g., the macroporous patch. The materials were characterized using solid state techniques. The drug delivery and permeation profiles of the patches were investigated applying in vitro and ex vivo tests by using porcine skin. These analyses suggest that scCO2 impregnation is an easy and fast strategy to prepare composite devices able to progressively release and diffuse the incorporated drug throughout the skin, paving the way to efficiently prepare cutaneous devices for topical or systemic therapies., This work was supported by the Spanish Ministry of Science and Innovation MICINN through the Severo Ochoa Program for Centers of Excellence (CEX2019–000917-S) and the Spanish National Plan of Research with projects CTQ2017–83632 and PID2020–115631GB-I00 (Concepción Domingo, Ana M. López and Márta Kubovics). Sara Rojas and Patricia Horcajada acknowledge the regional Madrid founding (Talento 2017 Modality 2, 2017-T2/IND-5149), the MOFSEIDON project (PID2019–104228RB-I00, MCI/AEI/FEDER, UE), and the Multifunctional Metallodrugs in Diagnosis and Therapy Network (MICIU, RED2018–102471-T). Márta Kubovics acknowledge the financial support from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Cofund grant (agreement no MSCA-COFUND-DP/0320–754397). Patricia Horcajada acknowledges the Spanish Ramon y Cajal Programme (grant agreement no. 2014–16823). Sara Rojas acknowledges the Spanish Juan de la Cierva Incorporación Fellowship (grant agreement no. IJC2019–038894-I). This work has been done in the framework of the doctoral program “Chemistry” of the Universitat Autònoma de Barcelona by Márta Kubovics.

The increasing complexity in composition and structure of modern porous nanocomposite materials requires the development of advanced technologies that allow the simultaneous treatment of dissimilar compounds, not only with unlike composition but also involving different classes of pores, e.g., micro and mesopores. This work shows that supercritical CO2 (scCO2) technology can be used as generic processing aid to obtain composites involving non-reduced graphene oxide (GO) and metal organic frameworks (MOFs) in the form of aerogels with hierarchical porosity. Hybrid aerogels are formed by either depositing (ex situ) or growing (in situ) MOF nanocrystals onto the surface of 2D GO nanosheets. The archetypal hydrophilic HKUST-1 and UiO-66 and hydrophobic ZIF-8 microporous MOFs are chosen to exemplify the method possibilities. The ex situ route was adequate to prepare hydrophilic MOFs@GO homogeneous composites, while the in situ approach must be used to prepare hydrophobic MOFs@GO aerogels. Moreover, the scCO2 methodology should be adjusted for each studied MOF in regard of the organic solvent used to disperse the nanoentities constituting the composite. The end-products are obtained in the form of aerogels mimicking the shape of the recipient in which they are contained. The products are characterized in regard of structure by X-ray diffraction, textural properties by low temperature N2 adsorption/desorption and morphology by electronic microscopy., This work was supported by the Spanish Ministry of Science and Innovation MICINN through the Severo Ochoa Program for Centers of Excellence (SEV-2015-0496 and CEX2019-000917-S) and the Spanish National Plan of Research with projects CTQ2017-83632, PID2020-115631GB-I00. This work has been done in the framework of the doctoral program “Chemistry” of the Universitat Autònoma de Barcelona by A.B., A.R. and J.F.; A.B. and A.R. acknowledge FPI grants., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

Fine chemical and pharmaceutical companies often employ reactive crystallization or precipitation to make crystalline intermediates and finished products. In this work, the supercritical reactive crystallization route is used for the precipitation of diverse metal–organic frameworks (MOFs). 1D and 2D MOFs were obtained by reacting either bypyridil (two linking positions) or triazine (three linking positions)-based bridging molecules, respectively, with supercritical CO2 soluble M(hfacac)2 (where M = Zn2+ or Cu2+ and hfacac– stands for hexafluoroacetylacetonate). Additionally, miscellaneous reactions were designed for the crystallization of 3D MOFs in scCO2, embracing the precipitation of MIL-88B(Fe), ZIF-8, and a new Zn2+–curcumin coordination polymer. Obtained crystals in each case were analyzed from a morphological point of view by scanning electron microscopy analysis to elucidate potential formation mechanisms. The focus was on the obtained crystal habits at different reaction points, linked to the pr...

The present work examines the functionalization of silica supports via supercritical CO2 grafting of aminosilanes, which is an important step in the preparation of materials used as solid sorbents in CO2 capture. Four materials have been considered as solid supports: two commercially available silica gels (4.1 and 8.8 nm pore diameter), the mesoporous silica MCM-41 (3.8 nm pore diameter) and a microporous faujasite of the Y type. Mono- and di-aminotrialkoxysilane were chosen for this study. The optimal operating conditions required to have free aminosilane in solution were first evaluated by studying the phase behavior of the system scCO2/aminosilane at different pressures and temperatures. FTIR spectroscopy was used to determine the chemical structure of the grafted species. Aminosilane uptake was estimated by thermogravimetric and elemental analysis. Densities up to 3–4 molecules of monoaminosilane per nm−2 were reached by using a small amount of a cosolvent together with the supercritical CO2. The samples were characterized in regards of thermal stability, showing that aminosilane groups were covalently attached to the amorphous silica surface in the mesoporous supports, but not in the microporous zeolite. Low temperature N2 and ambient temperature CO2 isotherms were recorded to establish the adsorptive behavior of the prepared hybrid materials. The amine functionalized MCM-41 and the 8.8 nm silica gel exhibited a significant higher uptake of CO2 at low pressures compared with the bare supports. On the contrary, for the 4 nm silica gel and the zeolite the adsorption decreased after impregnation.

The controlled aggregation of copper oxide nanoparticles (CuO NPs) induced by a multitopic carboxylic acid allows the formation of mesoporous structures with high surface area, in the order of 100 m2 g−1, as demonstrated herein. The main novelty in the designed process is the use, as a previous step, of a sacrificeable monotopic carboxylate ligand for capping the CuO NPs. This step avoids the often observed unwanted behavior of uncontrolled aggregation and material densification. The monotopic 3,6,9-trioxadecanoate (HTODA) is used as the capping agent to prepare TODA@CuO, a starting material that forms colloidal dispersions in ethanol. For NPs self-assembly, the bulky tricarboxylic acid 4,4′,4′′,-benzene-1,3,5-triyl-tris(benzoic acid) (H3BTB) is chosen as an efficient interlinker in the controlled aggregation. The obtained mesoporous network shows a considerable thermal stability, retaining ≈70% of its specific surface area after annealing at 300 °C under vacuum. Thermal treatment involves TODA capping agent elimination, but not BTB linker. The simultaneous reduction of the CuO NPs to a Cu2O/Cu mixture is observed.

scCO2 technology was used for the impregnation of microporous zeolites with organic molecules. Specifically, faujasite Y was impregnated with 1,3,5-triphenyl-2-pentene-1,5-dione that after reacting with the acid sites of the zeolite large cavities, formed the 2,4,6-triphenylpyrylium cation. Since the triphenylpyrylium cation has a size higher than the diameter of the zeolite channels, the fabrication method was considered as a ship-in-a-bottle procedure. To optimize the loading, different pressures and temperatures were tested in both the diffusion and cyclisation steps used in the impregnation supercritical process. The obtained impregnated samples were purified either by conventional Soxhlet extraction with dichloromethane or by cleaning with a scCO2 continuous flow. Loaded amounts of ca. 4–7 wt% were obtained following the supercritical procedure, which resulted more time-effective than the conventional procedure based in the use of organic solvents. Samples obtained were analyzed by thermal analysis, UV–vis and IR spectroscopy and characterization of surface area and micropore volume.

In this paper we present the precipitation of hydroxyapatite (HA), Ca 5 (OH)(PO 4 ) 3 , from highly concentrated CaCl 2 and K 2 HPO 4 solutions, carried out by a continuous method in a MSMPR reactor. The procedure consists of adding the reagents in a ratio Ca to P equal to 1.67, maintaining a temperature of 85°C, inert N 2 atmosphere inside the reactor, and monitoring and adjusting automatically the pH by means of a pH-stat system (pH =9.0 ± 0.1). Under these conditions HA with a Ca to P ratio equal or close to the stoichiometric composition (Ca/P = 1.667), with a high yield (up to 99%) and a high production rate (up to 1.17 g/l.min) is obtained at steady state. The CSD, morphology, crystallinity of the precipitates and impurities present fit the requirement for its biomedical applications.

Publicación versión online: 6 de agosto de 2007, This study aims to analyze the effects of supercritical carbon dioxide (SCCO2) on the carbonation of Portland cement pastes, with and without mineral addition. The process is based on the advantages of the low viscosity and surface tension of SCCO2 that allow the complete wetting of complex substrates with intricate geometries, including internal surfaces of agglomerates such of these found in cement pastes. The supercritical treatment alters the bulk chemical and structural properties of cement pastes by accelerating natural carbonation reactions, while at the same time it reduces both free and bound water. The observed overall effects of supercritical carbonation on Portland cement pastes were the neutralization of pore water alkalinity, the formation of calcium carbonate and the reduction in the Ca/Si ratio of the calcium silicate hydrate (CSH) gel. Moreover, the massive precipitation of calcium carbonate inside microcracks after supercritical treatment caused the refinement of the microstructure, thus, reducing water permeability to a large extent. Supercritical carbonation method can be completed in few hours, rendering it technically interesting. This work also contributes to the idea of increasing the durability of concrete by means of a preventive hydrophobic supercritical treatment against water ingress. A generic SCCO2 method for concrete silanization is proposed here., The financial support of EU Project STRP SurfaceT NMP2-CT-2005-013524 is greatly acknowledged. Carlos A. García-González gives acknowledgement to CSIC for its funding support through a I3P fellowship.

11 pages, 5 figures, 3 tables., In this work a mechanism for the precipitation of chain-like calcite agglomerates is proposed and compared to those ones leading to nano- and microcalcite in the system Ca(OH)2–CO2–H2O. The experiments were carried out by semicontinuous carbonation of a slaked lime (Ca(OH)2) suspension at 20°C, 25°C and 30°C, fixing the suspension conductivity at 5 mS/cm. The processes at 20°C and 25°C were essentially similar except in the final stage. Basically, they both occurred via surface and were characterized by the initial precipitation of amorphous calcium carbonate followed by its crystallization into chain-like aggregates of calcite. These aggregates acted as an intermediate for the final products: spheroidal nanometric calcite at 20°C and submicrometric chain-like calcite agglomerates (similar to batons) at 25°C. On the other hand, at 30°C, the precipitation took place preferentially via solution, producing micrometric calcite of scalenohedral habit as final product. The change in the mechanism of precipitation from preferentially via surface (at 20°C and 25°C) to preferentially via solution (at 30°C) seems to be directly related to the availability of Ca(OH)2 surface in the reaction mixture during the first steps of precipitation., We acknowledge Cales de Llierca, SA for providing the slaked lime used in this work. Our research team belongs to the Excellence Research Team 99SGR-00207 financed by the Autonomous Government of the Generalitat de Catalunya, Spain.