Influence of the Surface Chemistry of Metal-Organic Polyhedra in Their Assembly into Ultrathin Films for Gas Separation

The formation of ultrathin films of Rh-based porous metal-organic polyhedra (Rh-MOPs) by the Langmuir-Blodgett method has been explored. Homogeneous and dense monolayer films were formed at the air-water interface either using two different coordinatively alkyl-functionalized Rh-MOPs (HRhMOP(diz)12 and HRhMOP(oiz)12) or by in situ incorporation of aliphatic chains to the axial sites of dirhodium paddlewheels of another Rh-MOP (OHRhMOP) at the air-liquid interface. All these Rh-MOP monolayers were successively deposited onto different substrates in order to obtain multilayer films with controllable thicknesses. Aliphatic chains were partially removed from HRhMOP(diz)12 films post-synthetically by a simple acid treatment, resulting in a relevant modification of the film hydrophobicity. Moreover, the CO2/N2 separation performance of Rh-MOP-supported membranes was also evaluated, proving that they can be used as selective layers for efficient CO2 separation. © 2022 The Authors. Published by American Chemical Society

Influence of the surface chemistry of metal-organic polyhedra in their assembly into ultrathin films for gas separation

The formation of ultrathin films of Rh-based porous metal–organic polyhedra (Rh-MOPs) by the Langmuir–Blodgett method has been explored. Homogeneous and dense monolayer films were formed at the air–water interface either using two different coordinatively alkyl-functionalized Rh-MOPs (HRhMOP(diz)12 and HRhMOP(oiz)12) or by in situ incorporation of aliphatic chains to the axial sites of dirhodium paddlewheels of another Rh-MOP (OHRhMOP) at the air–liquid interface. All these Rh-MOP monolayers were successively deposited onto different substrates in order to obtain multilayer films with controllable thicknesses. Aliphatic chains were partially removed from HRhMOP(diz)12 films post-synthetically by a simple acid treatment, resulting in a relevant modification of the film hydrophobicity. Moreover, the CO2/N2 separation performance of Rh-MOP-supported membranes was also evaluated, proving that they can be used as selective layers for efficient CO2 separation.This work was funded by MCIN/AEI/10.13039/501100011033 and ERDF “A way of making Europe” (grant PID2019-105881RB-I00). The authors also acknowledge the support from the Spanish MINECO (project RTI2018-095622-B-I00) and the Catalan AGAUR (project 2017 SGR 238). It was also funded by the CERCA Programme/Generalitat de Catalunya and through a fellowship (LCF/BQ/PR20/11770011) from “la Caixa” Foundation (ID 100010434). ICN2 is supported by the Severo Ochoa programme from the Spanish MINECO (grant no. SEV-2017-0706). I.T. and M.P.-M. gratefully acknowledge their DGA PhD fellowship from Government of Aragon. The microscopy work was carried out in the Laboratorio de Microscopias Avanzadas at the Instituto de Nanociencia y Materiales de Aragon (LMA-INMA). This work benefited from the use of the SasView application, originally developed under NSF award DMR-0520547. SasView contains code developed with funding from the European Union’s Horizon 2020 research and innovation programme under the SINE2020 project, grant agreement no. 654000. The authors thank the synchrotron SOLEIL for beamtime provision under projects 20190435 and 20191874.Peer reviewe

Supporting information for the manuscript Influence of the Surface Chemistry of Metal–Organic Polyhedra in Their Assembly into Ultrathin Films for Gas Separation

19 pages. -- Figure S1. Absorption spectra (450-650 nm range) of OHRhMOP dissolved in methanol/chloroform (1:5) and the product formed after the addition of ca. 3.8×10- 3 mmol of diz to a dispersion of ca. 1.5×10-4 mmol OHRhMOP in 2 mL of THF. The maximum absorption at ca. 552 nm after diz addition indicates that all the dirhodium paddlewheels of OHRhMOP are coordinated to one diz, obtaining OHRhMOP(diz)12. -- Figure S2. Raw GIXD data for C12RhMOP (left), HRhMOP(diz)12 (middle) and OHRhMOP (right), at the indicated pressures. The water subphase data are shown as grey lines. Insets highlight the q range exhibiting the Bragg peak of alkyl chains ordering, in the case of C12RhMOP and HRhMOP(diz)12. -- Figure S3. Top: high q portion of GIXD data for C12RhMOP (left, collapsed) and HRhMOP(diz)12 (right, 10 mN/m), integrated over only the bottom half, top half, bottom first quarter or the whole detector, as indicated. The Bragg peak at ca. 1.51 Å-1 characteristic of alkyl chain interdigitation/order is not present in the data at higher qz. Bottom: intensity of the alkyl chains Bragg rod vs. qz, C12RhMOP. -- Figure S4. GIXD data for OHRhMOP at the gas-water interface at 10 mN/m, after correction for the water subphase. The red line is the diffusion form factor of coreshell spheres with an empty (SLD = 0) core of 5 Å radius and a dense shell of 11.5 Å thickness (SLD = 2x10-6 Å-2), considering a pinhole instrumental smearing dQ/Q of 5 %, that can only account for the two stronger peaks at 0.63 and 0.87 Å–1. (left), HRhMOP(diz)12 (right) at 10 mN/m. -- Scheme S1. LS sequential deposition of MOP monolayers onto PTMSP supports. One MOP monolayer is deposited each time that the support contacts the film formed at the air-liquid interface. After each transfer, the film is dried with N2 at ambient temperature and the transference is repeated as many times as necessary to obtain films with the desired number of Rh-MOP monolayers. -- Figure S5. UV-Vis spectra for the three Rh-MOPs studied. Solution spectra and LS films deposited onto quartz substrates are compared for each Rh-MOP. -- Figure S6. Representative AFM topography images from HRhMOP(oiz)12 and HRhMOP(diz)12 LS films transferred onto quartz substrates at 20 mN/m used to evaluate the film thickness. -- Figure S7. Representative AFM topography image of quartz, left, and a Si(100), right, substrates before MOP film deposition. -- Figure S8. Representative AFM topography and phase images from a OHRhMOP LS film transferred at 2 mN/m and evaluation of film thickness and defects dimensions. -- Figure S9. Linear increase of the absorbance at 214 nm vs. the number of Rh- MOP LS layers transferred at 20 mN/m onto quartz substrates (● HRhMOP(oiz)12;■: HRhMOP(diz)12). -- Figure S10. Rh-MOP mass deposited onto QCM disks at 20 mN/m versus the number of LS layers transferred (■: C12RhMOP;▲: HRhMOP(oiz)12, ●: HRhMOP(diz)12). -- Figure S11. Brewster Angle Microscope (BAM) images obtained during OHRhMOP + diz film compression at indicated surface pressures and the corresponding areas per molecule. OHRhMOP + diz different ratios were used in the experiments (1:25 in top images, and 1:50 in bottom images, respectively). -- Figure S12. Characterization of the films obtained from OHRhMOP + diz (1:25) reaction at the air-liquid interface: a) UV-Vis spectra from sequential deposition of LS films transferred onto quartz at 20 mN/m. Inset: Linear increase of the absorbance at 221nm vs. the number of LS layers transferred. b) Mass deposited onto QCM disks vs. the number of LS layers transferred (red line: OHRhMOP +diz; blue line: HRhMOP(diz)12, green line: C12RhMOP). -- Figure S13: UV-Vis spectra from HRhMOP(diz)12 LS films deposited onto quartz at 20 mN/m before and after the acid treatment: 1 layer (continuous line) and 3 layers (dashed line). -- Figure S14. Representative AFM topography and phase images from a HRhMOP(diz)12 LS film (1 layer) deposited onto Si (100) before and after acid treatment with HCl vapors. -- Table S1: Parameters of the components used to simulate the Rh 3d high resolution XPS spectra (see Figure 9) of OHRhMOP (powder), 1 LS film deposited at 20 mN/m after OHRhMOP + diz (1:25) reaction at the air-liquid interface and drop-cast film obtained after OHRhMOP + diz (1:25) reaction in THF. -- Table S2: Comparison of the performance of MOP and PIM ultrathin films (30 LS monolayers deposited onto PTMSP membranes) in CO2/N2 (10/90 in volume) separation at 35 ºC. At least 2 different samples were fabricated and measured to provide the corresponding error estimations.The formation of ultrathin films of Rh-based porous metal–organic polyhedra (Rh-MOPs) by the Langmuir–Blodgett method has been explored. Homogeneous and dense monolayer films were formed at the air–water interface either using two different coordinatively alkyl-functionalized Rh-MOPs (HRhMOP­(diz)12 and HRhMOP­(oiz)12) or by in situ incorporation of aliphatic chains to the axial sites of dirhodium paddlewheels of another Rh-MOP (OHRhMOP) at the air–liquid interface. All these Rh-MOP monolayers were successively deposited onto different substrates in order to obtain multilayer films with controllable thicknesses. Aliphatic chains were partially removed from HRhMOP­(diz)12 films post-synthetically by a simple acid treatment, resulting in a relevant modification of the film hydrophobicity. Moreover, the CO2/N2 separation performance of Rh-MOP-supported membranes was also evaluated, proving that they can be used as selective layers for efficient CO2 separation.Peer reviewe

Solventless synthesis of ZIF-L and ZIF-8 with hydraulic press and high temperature

Trabajo presentado al Young Researchers CIS, celebrado online del 6 al 8 de septiembre de 2021.Financial support from the research project PID2019-104009RB-100 is gratefully acknowledge. M. P.-M. thanks the Aragon Government for her PhD grant.Peer reviewe

Síntesis sin disolvente de ZIF-L y ZIF-8 mediante prensa hidráulica a alta temperatura

Resumen del póster presentado a la 9ª Jornada de Jóvenes Investigadores de Química y Física de Aragón, celebrada en la Universidad de Zaragoza el 16 de diciembre de 2021.Se agradece el apoyo financiero del Proyecto de Investigación PID2019-104009RB-I00 / AEI / 10.13039 / 501100011033. M. P.-M. agradece al Gobierno de Aragón su beca de doctorado.Peer reviewe

Solventless synthesis of ZIF-L and ZIF-8 with hydraulic press and high temperature

In recent years, alternative methods to conventional synthesis of MOFs (metal-organic frameworks) have emerged due to the problematic use of solvents for both the environment and human health. Here we present the synthesis of ZIFs (zeolitic imidazolate frameworks) at high pressure by means of a hydraulic press provided with a heating mechanism. By the optimization of parameters such as temperature, time and the addition of promotor NH4NO3, a considerable increase in the reaction yield was achieved in products, neither washed nor activated, obtained since the first minute of reaction. Depending on the operation conditions, ZIF-L appeared as competing phase with ZIF-8. Upon transformation of ZIF-L into ZIF-8 in presence of ethanol, a reaction yield of 58.2% was achieved to highly crystalline ZIF-8 with a BET specific surface area of 947 m2/g. This green, fast, versatile and improved method suggests a possible way to future synthesis of other MOFs and the possibility of their industrial implementation.Financial support from the Research Projects MAT2016-77290-R and the PID2019-104009RB-I00/AEI/10.13039/501100011033 (Spanish AEI/FEDER, UE), the Aragón Government (T43-20R and Marta Pérez-Miana PhD grant) and the ESF are gratefully acknowledged. All the microscopy work was done in the Laboratorio de Microscopías Avanzadas (LMA). The authors acknowledge the LMA for offering access to their instruments and expertise and the Servicios de Apoyo a la Investigación (SAI), both from the Universidad de Zaragoza.Peer reviewe

Highly permeable ZIF-8 membranes for C2H4/C2H6 separation in a wide temperature range

Ethylene/ethane separation is a critical and energy-consuming process in the chemical industry due to the similar properties of the compounds and the great need of ethylene for e.g., polymer production. Many materials have been studied for their implementation as membranes as an energetically favorable alternative to conventional distillation and adsorption processes. Metal-organic frameworks (MOF) have revealed promising properties as highly permeable and selective membranes. Among the most studied and promising MOF candidates is ZIF-8, known for its thermal stability and small pores connected by narrow-sized windows. In this work, we present an analysis of the influence of parameters such as temperature, feed pressure and feed flowrate on the separation of ethylene/ethane through a thin ZIF-8/alumina disc membrane. We observed that the temperature has a significant effect on the separation. The ethylene permeance increased with decreased temperature and reached 8.1 × 10−7 mol/(m2·s·Pa) at −30 °C. At this temperature, the ethylene/ethane selectivity was 2.5. The study concluded with a considerable enhancement of the permeance of ZIF-8 membranes for ethylene/ethane separations, while maintaining a good selectivity compared to the reported values in the literature. The results have important implications for the development of more cost-effective and energy-efficient membrane-based separation technologies for ethylene purification.Validerad;2023;Nivå 2;2023-11-08 (marisr);License fulltext: CC BY-NC-ND</p

ZIF-8 modified with 2-undecylimidazolate as filler for mixed matrix membranes for CO₂ separation

A novel modification of zeolitic imidazolate framework-8 (ZIF-8) with 2-undecylimidazolate (umIm) was explored to enhance its hydrophobic character and improve its compatibility with polymer of intrinsic microporosity PIM-1 when incorporated as a filler in mixed matrix membranes (MMMs). In addition to the study of the best conditions to exchange the structural ligand of ZIF-8 by umIm and the characterization (by FTIR, RMN, XRD, TGA, N2 adsorption and TEM) of the obtained material, comparative analyses were conducted using MMMs containing the original ZIF-8 and the modified version. Different loadings were applied to study the impact on gas separation properties. Remarkably, the MMM with the modified ZIF-8 demonstrated superior performance surpassing the Robeson upper bound line of 2008 and revealing the effectiveness of this MOF modification strategy. In fact, with the 10 wt% ZIF-8-umIm loading MMM, the highest value of CO2/N2 selectivity was 15.4 (12% higher than that of bare PIM-1) at a CO2 permeability of 16 667 Barrer (52% higher than that of bare PIM-1). These findings highlight the promising potential of the ZIF-8 modification with umIm as a valuable filler material for MMMs in gas separation applications

Optimisation et application des améliorations dans l'évaluation des compétences transversales conçues à partir de la vision multidisciplinaire d'ApreRED

The specific competences are acquired by the students and certified by passing the different subjects of the study plans. However, soft skills are not systematically worked on and are not evaluated, which means that their acquisition cannot be guaranteed. However, these skills are a fundamental basis in higher education and in the future employment of university graduates. The current methodological paradigm of Higher Education shows the importance of authentic and alternative evaluation of learning, based on relevant activities or execution tasks. AprenRED's work in recent years has focused on the field of soft skills. In this case, the objective of this study is to optimize and improve the strategies and instruments for evaluating soft skills, based on the results obtained in recent years, from our multidisciplinary perspective.Las competencias específicas son adquiridas por los estudiantes y certificadas mediante la superación de las diferentes materias de los planes de estudio. Sin embargo, las competencias transversales no se trabajan sistemáticamente y no se evalúan, lo que implica que no pueda garantizarse su adquisición. Sin embargo, dichas competencias son base fundamental en la formación superior y en la futura inserción laboral de los graduados universitarios. El actual paradigma metodológico de la Educación Superior muestra la importancia de la evaluación auténtica y alternativa de los aprendizajes, a partir de actividades o tareas de ejecución relevantes. El trabajo de AprenRED durante los últimos años se ha centrado en el campo de las competencias transversales. En este caso, el objetivo de este trabajo es optimizar y mejorar las estrategias e instrumentos de evaluación de las competencias transversales, en base a los resultados obtenidos en los últimos años, desde nuestra visión multidisciplinar.Des compétences spécifiques sont acquises par les étudiants et certifiées par la réussite des différentes matières des plans d'études. Cependant, les compétences transversales ne sont pas systématiquement travaillées et ne sont pas évaluées, ce qui ne permet pas de garantir leur acquisition. Or, ces compétences constituent une base fondamentale dans l'enseignement supérieur et dans l'emploi futur des diplômés universitaires. Le paradigme méthodologique actuel de l'enseignement supérieur montre l'importance d'une évaluation authentique et alternative des apprentissages, basée sur des activités ou des tâches d'exécution pertinentes. Le travail d'ApreRED ces dernières années s'est concentré sur le domaine des compétences transversales. Dans ce cas, l'objectif de ce travail est d'optimiser et d'améliorer les stratégies et les instruments d'évaluation des compétences transversales, sur la base des résultats obtenus ces dernières années, à partir de notre vision multidisciplinaire

Optimización y aplicación de rúbricas en la evaluación de competencias transversales, diseñadas desde la visión multidisciplinar de aprenred

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