Aerogels of 1D Coordination Polymers: From a Non-Porous Metal-Organic Crystal Structure to a Highly Porous Material

The processing of an originally non- porous 1D coordination polymer as monolithic gel, xerogel and aerogel is reported as an alternative method to obtain novel metal- organic porous materials, conceptually different to conventional crystalline porous coordination polymer ( PCPs) or metal- organic frameworks ( MOFs). Although the work herein reported is focused upon a particular kind of coordination polymer ([ M( mu - ox)( 4- apy) 2] n, M: Co( II), Ni( II)), the results are of interest in the field of porous materials and of MOFs, as the employed synthetic approach implies that any coordination polymer could be processable as a mesoporous material. The polymerization conditions were fixed to obtain stiff gels at the synthesis stage. Gels were dried at ambient pressure and at supercritical conditions to render well shaped monolithic xerogels and aerogels, respectively. The monolithic shape of the synthesis product is another remarkable result, as it does not require a post- processing or the use of additives or binders. The aerogels of the 1D coordination polymers are featured by exhibiting high pore volumes and diameters ranging in the mesoporous/ macroporous regions which endow to these materials the ability to deal with large- sized molecules. The aerogel monoliths present markedly low densities ( 0.082- 0.311 g center dot cm - 3), an aspect of interest for applications that persecute light materials.This work has been funded by Ministerio de Economia y Competitividad (MAT2013-46502-C2-1-P), Eusko Jaurlaritza/Gobierno Vasco (Grant IT477-10) and Universidad del Pais Vasco/Euskal Herriko Unibertsitatea (EHUA14/09, UFI 11/53, postdoctoral fellowship for Sonia Perez-Yanez). Technical and human support provided by SGIKer (UPV/EHU, MINECO, GV/EJ, ERDF, and ESF) is gratefully acknowledged

Slot-Die Process of a Sol–Gel Photocatalytic Porous Coating for Large-Area Fabrication of Functional Architectural Glass

The slot-die process is an appealing technology for the fabrication of coatings on large-area substrates. However, its application on the production of photocatalytic coatings based on sol–gel formulations remains virtually unexplored. Thus, assessing the suitable formulation of the sol and operational parameters that allow one to yield high-efficacy photocatalyst coatings is a current challenge. This work aims to analyze the transferability of titania sol formulation optimized for dip-coating processes to slot-die technology. In this sense, firstly, the sol formulation is optimized by analyzing the influence of several types of surfactants on the microstructural features and photoactivity of TiO2 coatings’ growth on glass substrates. All formulations rendered a meaningful porosity and nanoscopic anatase crystallites (11–15 nm) with optical band gap values close to the expectation (3.25–3.31 eV). Accordingly, the performance of the photocatalytic dye degradation was closely related to the porosity and crystallite size led by each titania sol, and no meaningful differences were found between the results provided by the coatings developed by dip-coating and the slot-die method, which demonstrates the capability of the latter for its application on a large-scale fabrication of photocatalytic coatings.This research was funded by the Basque Government (IT1291-19), the Spanish Ministry of Science and Innovation (MICINN project: PID2019-108028GB-C21), and the European Union’s Horizon 2020 research and innovation program (grant agreement N° 792103 SOLWARIS)

Misleading urbanization? The San Ramon fault as a new seismic risk scenario and the sustainability of Santiago, Chile

Santiago, capital city of Chile inhabited by ca. 7 million persons (INE, 2018), is located at the foot of the western flank of the main Andes Cordillera, which is one of the most active mountain chains worldwide. The eastern border of the city, located at the piedmont of the mountain front, experienced an accelerated urbanization in the last four decades with respect to the previous four centuries, with subsequent increased risk associated to geological hazards among of them the possibility for crustal earthquakes along the active San Ramon thrust fault system. Here, we explore this new seismic risk scenario by comparing first order urban mapping at different stages of the horizontal expansion of the city, including the location of the geological structure, with urban policies developed since 1960. Our results show that -at present- urbanization reached 55% of the San Ramon fault trace, evidencing that this active geological structure has not been considered in urban regulations developed for the metropolitan region. We conclude the necessity to unravel normative and knowledge gaps in order to relate the natural geological hazard with the urban planning, as an opportunity to progress toward a sustainable development of the mega-city of Santiago

A metal-organic framework based on Co(II) and 3-aminoisonicotinate showing specific and reversible colourimetric response to solvent exchange with variable magnet behaviour

[EN] A versatile metal-organic system consisting of Co-based compounds that show reversible transformations between a 3D metal-organic framework (MOF) of {[Co(mu-3isoani)(2)]center dot DMF}(n) (1) formula (where 3isoani - 3-aminoisonicotinato and DMF - dimethylformamide) and a 0D monomeric [Co(3isoani)(2)(H2O)(4)] (2) complex is reported. These 1 2 transformations, triggered by the exposure of the MOF and the monomer-based compound to H2O and DMF, respectively, involve colour changes from purple (in MOF 1) to light brown (in monomeric complex 2), which imbues the system with colourimetric sensing capacity towards these solvents. Despite the high reactivity of the MOF in contact with water, it presents good thermal stability and permanent porosity with a remarkably high CO2 capture capacity at room temperature (3.35 mmol/g), which is further analysed by in situ single-crystal X-ray diffraction. Experimental magnetic properties and CASSCF/NEVPT2 calculations of all compounds reveal distinct slow magnetic relaxations for 3D and 0D compounds.This work has been funded by the Spanish Ministry of Science, Innovation and Universities (MCIU/AEI/FEDER, UE; PGC2018-102052-A-C22, PGC2018-102052-B-C21 and PID2019-108028GBC21), University of the Basque Country (GIU20/028), Gobierno Vasco/Eusko Jaurlaritza (IT1005-16, IT1291-19) and Junta de Andalucia (FQM-394, B-FQM-734-UGR20). O.P.C. thanks his predoctoral fellowship to UPV/EHU. The authors thank for technical and human support provided by SGIker of UPV/EHU and European funding (ERDF and ESF)

Thermochemical CO2 reduction catalyzed by homometallic and heterometallic nanoparticles generated from the thermolysis o supramolecularly assembled porous metal-adenine precursors

A family of unprecedented supramolecularly assembled porous metal–organic compounds (SMOFs), based on [Cu6M(μ-adeninato)6(μ3-OH)6(μ-H2O)6]2+ cations (MII: Cu, Co, Ni, and Zn) and different dicarboxylate anions (fumarate, benzoate, and naphthalene-2,6-dicarboxylate), have been employed as precursors of catalysts for the thermocatalytic reduction of CO2. The selected metal–organic cation allows us to tune the composition of the SMOFs and, therefore, the features and performance of the final homometallic and bimetallic catalysts. These catalysts were obtained by thermolysis at 600 °C under a N2 atmosphere and consist of big metal particles (10–20 μm) placed on the surface of the carbonaceous matrix and very tiny metal aggregates (<10 nm) within this carbonaceous matrix. The latter are the most active catalytic sites for the CO2 thermocatalytic reduction. The amount of this carbonaceous matrix correlates with the organic content present in the metal–organic precursor. In this sense, CO2 thermocatalytic reduction experiments performed over the homometallic, copper only, catalysts with different carbon contents indicate that above a certain value, the increase of the carbonaceous matrix reduces the overall performance by encapsulating the nanoparticles within this matrix and isolating them from interacting with CO2. In fact, the best performing homometallic catalyst is that obtained from the precursor containing a small fumarate counterion. On the other hand, the structural features of these precursors also provide a facile route to work with a solid solution of nanoparticles as many of these metal–organic compounds can replace up to 1/7 of the copper atoms by zinc, cobalt, or nickel. Among these heterometallic catalysts, the best performing one is that of copper and zinc, which provides the higher conversion and selectivity toward CO. XPS spectroscopy and EDX mappings of the latter catalyst clearly indicate the presence of Cu1–xZnx nanoparticles covered by small ZnO aggregates that provide a better CO2 adsorption and easier CO release sites.Eusko Jaurlaritza/Gobierno Vasco (IT1291-19; IT1722-22 and Investigo program for S.M.G. funded by the European Union-Next Generation EU). Universidad del País Vasco/Euskal Herriko Unibertsitatea (predoctoral fellowship for J.P.C. 17/051), Ministerio de Ciencia e Innovación (project PID2019-108028GB-C21 funded by MCIN/AEI/10.13039/501100011033; PID2022-138968NB-C22 funded by MCIN/AEI/10.13039/501100011033/FEDER/FEDER, and TED2021-129810B-C22 funded by MCIN/AEI/10.13039/501100011033 and by the European Union NextGeneration EU/PRTR)

Metal-organic aerogels based on titanium(IV) for visible-light conducted CO2 photoreduction to alcohols

Metal-organic frameworks (MOFs) imply an appealing source of photocatalysts as they combine porosity with tailorable electronic properties and surface chemistry. Herein, we report a series of unprecedented metal-organic aerogels (MOAs) comprised by Ti(IV) oxo-clusters and aromatic dicarboxylic linkers as an alternative to microporous MIL-125 and MIL-125-NH2 MOFs. Discrete titanium oxo-clusters polymerized upon the addition of the dicarboxylic linkers to give rise to a metal-organic gel. Their supercritical drying led to aerogels comprised by nanoscopic particles (ca. 5-10 nm) cross-linked into a meso/macroporous microstructure with surface area ranging from 453 to 617 m2·g-1, which are comparatively lower than the surface area of the microporous counterparts (1336 and 1145 m2·g-1, respectively). However, the meso/macroporous microstructure of MOAs can provide a more fluent diffusion of reagents and products than the intrinsic porosity of MOFs, whose narrower channels are expected to imply a more sluggish mass transport. In fact, the assessment of the continuous visible-light-driven photocatalytic CO2 reduction into methanol shows that MOAs (221-786 [M] mol·g-1·h-1) far exceed not only the performance of their microporous counterparts (49-65 [M]mol·g-1·h-1) but also surpass the production rates provided by up-to-date reported photocatalysts.The authors gratefully acknowledge the financial support from the European Union's Horizon 2020 research and innovation program (grant agreement No.101037428), the Basque Government (KK-2016/ 00095-LISOL IT1291-19 and IT1722-22) and the Spanish Ministry of Science and Innovation (TED2021-129810B-C21 and TED2021- 129810B-C22 funded by MCIN/AEI/10.13039/501100011033 and Next Generation EU/PRTR, PID2019-108028GB-C21 and PID2019- 104050RA-I00 funded by MCIN/AEI/10.13039/501100011033). Technical and human support provided by SGIker (UPV/EHU, MICINN, GV/ EJ, and ESF) is also acknowledged

An in solution adsorption characterization technique based on the response to an external magnetic field of porous paramagnetic materials: application on supramolecular metal–adenine frameworks containing heterometallic heptameric clusters

Herein we explore the opportunities arising from combining magnetic properties and porosity in metal–organic materials. In this sense, we have prepared an adenine based homometallic wheel-shaped heptameric [Cu7(μ-adeninato)6(μ3-OH)6(μ-OH2)4]2+ entity containing two metal coordination environments: CuO6 at the core of the wheel with an unusually modest Jahn–Teller distortion and six peripheral CuN2O4 with a more pronounced elongation. The difference in the coordination environments of this compound facilitates the selective replacement of the central metal position by other metal centers (ZnII, NiII, CoII and CrIII) and boosts the magnetic properties of the homometallic heptameric entity. The nature of the central metal modulates the complex net of ferro- and antiferromagnetic superexchange pathways within the heptameric entity to tune the total spin (ST = 3 (Cu6Zn), 5/2 (Cu6Cu), 2 (Cu6Ni), 3/2 (Cu6Co), and 9/2 (Cu6Cr)). No evidence of single-molecule magnet behavior has been observed at 2 K, but at room temperature, where these compounds are still in the paramagnetic regime, the attraction force exerted by an external magnetic field (H) on particles immersed in a liquid is enough to keep them attached to an electromagnet pole. The 4S(S + 1) value of the central metal follows a linear dependence with respect to the 1/[H·∇(H)] value at which the particles are detached from the pole of the electromagnet. There is also a linear dependence of the H·∇(H) term with respect to the adsorbate mass incorporated inside the pores of the paramagnetic adsorbent which has allowed performing straightforward sorption selectivity experiments on Cu6Cu directly in solution, which are based on a property of the adsorbent and not as usually based on an indirect assessment of the adsorbate remaining in solution.Eusko Jaurlaritza/Gobierno Vasco (IT1291-19; IT1722-22; ELKARTEK program KK-2022/00032), Ministerio de Universidades and the European Union-Next Generation EU (marsa21/52, R. P. A.), Ministerio de Ciencia e Innovación (PID2019-108028GB-C21). SGIker (UPV/EHU, MICINN, GV/EJ, ESF). ELKARTEK program KK-2022/0003

Isoreticular chemistry and applications of supramolecularly assembled copper−adenine porous materials

The useful concepts of reticular chemistry, rigid and predictable metal nodes together with strong and manageable covalent interactions between metal centers and organic linkers, have made the so-called metal–organic frameworks (MOFs) a flourishing area of enormous applicability. In this work, the extension of similar strategies to supramolecularly assembled metal–organic materials has allowed us to obtain a family of isoreticular compounds of the general formula [Cu7(μ-adeninato-κN3:κN9)6(μ3-OH)6(μ-OH2)6](OOC-R-COO)·nH2O (R: ethylene-, acetylene-, naphthalene-, or biphenyl-group) in which the rigid copper–adeninato entities and the organic dicarboxylate anions are held together not by covalent interactions but by a robust and flexible network of synergic hydrogen bonds and π–π stacking interactions based on well-known supramolecular synthons (SMOFs). All compounds are isoreticular, highly insoluble, and water-stable and show a porous crystalline structure with a pcu topology containing a two-dimensional (2D) network of channels, whose dimensions and degree of porosity of the supramolecular network are tailored by the length of the dicarboxylate anion. The partial loss of the crystallization water molecules upon removal from the mother liquor produces a shrinkage of the unit cell and porosity, which leads to a color change of the compounds (from blue to olive green) if complete dehydration is achieved by means of gentle heating or vacuuming. However, the supramolecular network of noncovalent interactions is robust and flexible enough to reverse to the expanded unit cell and color after exposure to a humid atmosphere. This humidity-driven breathing behavior has been used to design a sensor in which the electrical resistance varies reversibly with the degree of humidity, very similar to the water vapor adsorption isotherm of the SMOF. The in-solution adsorption properties were explored for the uptake and release of the widely employed 5-fluorouracil, 4-aminosalycilic acid, 5-aminosalycilic acid, and allopurinol drugs. In addition, cytotoxicity activity assays were completed for the pristine and 5-fluorouracil-loaded samples.Basque Goverment (IT1722-22 and ELKARTEK KK-2022/00032) . Spanish Ministry of Science and Innovation (TED2021-129810B-C22 financed by MCIN/AEI/10.13039/501100011033 and by the European Union Next Generation EU/PRTR, and the PID2019-108028GB-C21 project funded by MCIN/AEI/10.13039/501100011033). Basque Government and the European Union Next GenerationEU (Investigo Program 2022-46)