Search

Herein we propose a new approach for deducing the topology of metal–organic frameworks (MOFs) assembled from organic ligands of low symmetry, which we call net-clipping. It is based on the construction of nets by rational deconstruction of edge-transitive nets comprising higher-connected molecular building blocks (MBBs). We have applied net-clipping to predict the topologies of MOFs containing zigzag ligands. To this end, we derived 2-connected (2-c) zigzag ligands from 4-c square-like MBBs by first splitting the 4-c nodes into two 3-c nodes and then clipping their two diagonally connecting groups. We demonstrate that, when this approach is applied to the 17 edge-transitive nets containing square-like 4-c MBBs, net-clipping leads to generation of 10 nets with different underlying topologies. Moreover, we report that literature and experimental research corroborate successful implementation of our approach. As proof-of-concept, we employed net-clipping to form three new MOFs built with zigzag ligands, each of which exhibits the deduced topology., This work was supported by the Spanish MINECO (project RTI2018-095622-B-I00), the Catalan AGAUR (project 2017 SGR 238), and the ERC under the EU-FP7 (ERC-Co 615954). It was also funded by the CERCA Program/Generalitat de Catalunya. ICN2 is supported by the Severo Ochoa program from the Spanish MINECO (Grant No. SEV-2017-0706).

Luminescent lanthanide metal-organic frameworks (Ln-MOFs) have been shown to exhibit relevant optical properties of interest for practical applications, though their implementation still remains a challenge. To be suitable for practical applications, Ln-MOFs must be not only water stable but also printable, easy to prepare, and produced in high yields. Herein, we design and synthesize a series of m CB-Eu y Tb 1-y (y = 0-1) MOFs using a highly hydrophobic ligand mCBL1: 1,7-di(4-carboxyphenyl)-1,7-dicarba-closo-dodecaborane. The new materials are stable in water and at high temperature. Tunable emission from green to red, energy transfer (ET) from Tb3+ to Eu3+, and time-dependent emission of the series of mixed-metal m CB-Eu y Tb 1-y MOFs are reported. An outstanding increase in the quantum yield (QY) of 239% of mCB-Eu (20.5%) in the mixed mCB-Eu0.1Tb0.9 (69.2%) is achieved, along with an increased and tunable lifetime luminescence (from about 0.5 to 10 000 μs), all of these promoted by a highly effective ET process. The observed time-dependent emission (and color), in addition to the high QY, provides a simple method for designing high-security anticounterfeiting materials. We report a convenient method to prepare mixed-metal Eu/Tb coordination polymers (CPs) that are printable from water inks for potential applications, among which anticounterfeiting and bar-coding have been selected as a proof-of-concept., This work was financially supported by the MINECO (PID2019-106832RB-I00), MICINN through the Severo Ochoa Program for Centers of Excellence for the FUNFUTURE (CEX2019-000917-S, MDM-2017-0767, and SEV-2017-0706 projects), grant RTI2018-098027-B-C21 funded by MCIN/AEI/10.13039/501100011033 and by ERDF A way of making Europe and the Generalitat de Catalunya (2017/SGR/1720 and SGR2017-1289). Z.L. is enrolled in the UAB Ph.D. program and acknowledges the China Scholarship Council (CSC) for his Ph.D. grant (201808310071)., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

The past 20 years have witnessed tremendous advances in the field of porous materials, including the development of novel metal–organic frameworks (MOFs) that show great potential for practical applications aimed at addressing global environmental and industrial challenges. A critical tool enabling this progress has been reticular chemistry, through which researchers can design materials that exhibit highly regular (i.e., edge-transitive) topologies, based on the assembly of geometrically matched building blocks into specific nets. However, innovation sometimes demands that researchers steer away from default topologies to instead pursue unusual geometries. In this Perspective, we cover this aspect and introduce the concept of geometry mismatch, in which seemingly incompatible building blocks are combined to generate non-default structures. We describe diverse MOF assemblies built through geometry mismatch generated by use of ligand bend angles, twisted functional groups, zigzag ligands and other elements, focusing on carboxylate-based MOFs combined with common inorganic clusters. We aim to provide a fresh perspective on rational design of MOFs and to help readers understand the countless options now available to achieve greater structural complexity in MOFs., This work was supported by the Spanish MINECO (project RTI2018-095622-B-I00) and the Catalan AGAUR (project 2017 SGR 238). It was also funded by the CERCA Program/Generalitat de Catalunya. ICN2 is supported by the Severo Ochoa program from the Spanish MINECO (Grant No. SEV-2017-0706).

Metal-organic frameworks (MOFs) offer a unique variety of properties and morphology of the structure that make it possible to extend the performance of existing and design new electrochemical biosensors. High porosity, variable size and morphology, compatibility with common components of electrochemical sensors, and easy combination with bioreceptors make MOFs very attractive for application in the assembly of electrochemical aptasensors. In this review, the progress in the synthesis and application of the MOFs in electrochemical aptasensors are considered with an emphasis on the role of the MOF materials in aptamer immobilization and signal generation. The literature information of the use of MOFs in electrochemical aptasensors is classified in accordance with the nature and role of MOFs and a signal mode. In conclusion, future trends in the application of MOFs in electrochemical aptasensors are briefly discussed. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. A.P. acknowledges support of the Russian Science Foundation (grant No 17-73-20024) in part related to the analysis of the reaction conditions and operation of the MOF aptasensors. T.H. acknowledges funding from the Science Grant Agency VEGA, project No.: 1/0419/20.

Herein we report a novel, ozone-based method for postsynthetic generation of mesoporosity in metal–organic frameworks (MOFs). By carefully selecting mixed-ligand Zr-fcu-MOFs based on organic ligand pairs in which one ligand has ozone-cleavable olefin bonds and the other ligand is ozone-resistant, we were able to selectively break the cleavable ligand via ozonolysis to trigger fusion of micropores into mesopores within the MOF framework. This solid–gas phase method is performed at room-temperature, and, depending on the cleavable ligand used, the resultant ligand-fragments can be removed from the ozonated MOF by either washing or sublimation. Compared to the corresponding highly microporous starting MOFs, the highly mesoporous product MOFs exhibit radically distinct gas sorption properties., This work was supported by the Spanish MINECO (projects PN MAT2015-65354-C2-1-R), the Catalan AGAUR (project 2014 SGR 80), and the ERC under the EU-FP7 (ERC-Co 615954). It was also funded by the CERCA Programme/Generalitat de Catalunya. ICN2 acknowledges the support of the Spanish MINECO through the Severo Ochoa Centres of Excellence Programme, under Grant SEV-2013-0295. V.G. thanks the Generalitat de Catalunya for a Beatriu de Pinós fellowship (2014 BP-B 00155) (Marie Curie Fellowship, EU funded project ITHACA). J.A. and H.X. acknowledge the Generalitat de Catalunya for FI fellowships.

Covalent postsynthetic modification (PSM) of metal-organic frameworks (MOFs) has attracted much attention due to the possibility of tailoring the properties of these porous materials. Schiff-base condensation between an amine and an aldehyde is one of the most common reactions in the PSM of MOFs. Here, we report the use of the spray drying technique to perform this class of organic reactions, either between discrete organic molecules or on the pore surfaces of MOFs, in a very fast (1-2 s) and continuous way. Using spray drying, we show the PSM of two MOFs, the amine-terminated UiO-66-NH2 and the aldehyde-terminated ZIF-90, achieving conversion efficiencies up to 20 and 42%, respectively. Moreover, we demonstrate that it can also be used to postsynthetically cross-link the aldehyde groups of ZIF-90 using a diamine molecule with a conversion efficiency of 70%.

Innovative bimetallic MOFs offer more possibilities to further tailor the properties of MOFs, which have attracted great attention for wide applications. However, it is still a great challenge to rationally design bimetallic MOFs due to the lack of a tunable and reasonable hybrid structure architecture. Herein, a new series of bimetallic metal–organic frameworks (MOFs) with tunable pillar linkers were prepared by a one-step synthesis method. These bimetallic MOFs retain the same crystal structure when the mole fraction (based on metal) of the two metals changes from 0 to 1 and both metal ions occupy random nodal positions. The incorporation of a second metal cation has a large influence on the intrinsic properties (e.g. thermal stabilities and band gaps) of the MOFs. Furthermore, these bimetallic MOFs were used as self-sacrificial templates to prepare bimetal oxide catalysts for the oxygen evolution reaction (OER). After pyrolysis, a porous and hierarchical honeycomb-like structure with carbon network covered (bi)metal oxides is formed. Among all the bimetallic MOF-derived catalysts, CoNi1@C showed the best performance for the OER with the lowest Tafel slopes (55.6 mV dec−1) and overpotentials (335 mV on a glassy carbon electrode and 276 mV on Ni foam) at a current density of 10 mA cm−2, which is higher than those of state-of-the-art Co–Ni mixed oxide catalysts derived from MOFs for the OER. Our results indicate that the incorporation of a second metal ion is a promising strategy to tailor the properties of MOFs. More importantly, this new bimetallic MOF family with tunable linkers is expected to serve as a flexible assembly platform to offer broad possibilities for practical applications of MOFs., X. Zhang is grateful to the China Scholarship Council. J. Luo acknowledges the Research Foundation – Flanders (FWO) for a Research Project (G0B3218N), a Research Grant (1529816N) and a travel grant (V410316N) for a Visiting Professorship at the Technical University of Denmark. TZ, PYT and JA acknowledge funding from Generalitat de Catalunya 2017 SGR 327 and the Spanish MINECO project VALPEC (ENE2017-85087-C3). ICN2 acknowledges support from the Severo Ochoa Programme (MINECO, Grant no. SEV-2017-0706) and is funded by the CERCA Programme/Generalitat de Catalunya. Part of the present work has been performed in the framework of the Universitat Autònoma de Barcelona Materials Science PhD program. TZ has received funding from the CSC-UAB PhD scholarship program. D. P. acknowledges the Research Foundation – Flanders (FWO) for a Ph.D. (aspirant) Fellowship. We thank Iris Cuppens and Dr Fei Wang (Department of Materials Engineering, KU Leuven) for the assistance with EPMA and ICP measurements. Funding from the National Natural Science Foundation of China (No. 21776120), “Minjiang Scholar” Program and key project (No. JZ160480) of Department of Education, Fujian Province, China, and Open Project (No. 201607) of State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University is also acknowledged.

[EN] A series of mixed-metal Fe-III/Ni-II metal-organic frameworks (MOFs) of the MIL-100 type containing different metal ratios have been synthesized de novo, following an approach that requires tuning of the Fe-III/Ni-II reactivity. The resulting heterometallic MIL-100(Fe, Ni) materials maintain thermal, chemical and structural stability with respect to the parent MIL-100(Fe) MOF as can be deduced from various techniques. The nature and the oxidation state of the accessible metal cations have been evaluated by in situ infrared spectroscopy and extended X-ray absorption fine structure measurements. The obtained mixed-metal MOFs and the parent material have been evaluated as heterogeneous catalysts in a model acid-catalyzed reaction, i.e., the Prins reaction. It is found that the catalytic activity improves by more than one order of magnitude upon incorporation of Ni-II, with a complete selectivity for the formation of nopol. This increase in the catalytic activity upon incorporation of Ni-II correlates with the enhancement in the Lewis acidity of the material as determined by CO adsorption. The heterometallic MOF can be recycled without observation of metal leaching, while maintaining the crystal structure under the reaction conditions., This work was supported by the European Commission under the Marie Sklodowska-Curie agreement H2020-MSCA-IF-658224. Measurements at the ROCK synchrotron beamline of SOLEIL were supported by a public grant overseen by the French National Research Agency (ANR) as part of the "Investissements d'Avenir" program (reference: ANR10-EQPX45). H. G. thanks financial support by the Spanish Ministry of Science and Innovation (Severo Ochoa and RTI2018-098237-CO21) and Generalitat Valenciana (Prometeo 2017/083). S. N. thanks financial support by the Fundacion Ramon Areces (XVIII Concurso Nacional para la Adjudicacion de Ayudas a la Investigacion en Ciencias de la Vida y de la Materia, 2016) and Ministerio de Ciencia, Innovacion y Universidades CTQ-2018 RTI2018-099482-A-I00 project.

Herein we describe the topological influence of zigzag ligands in the assembly of Zr(IV) metal–organic frameworks (MOFs). Through a transversal design strategy using reticular chemistry, we were able to synthesize a family of isoreticular Zr(IV)-based MOFs exhibiting the bcu—rather than the fcu—topology. Our findings underscore the value of the transversal parameter in organic ligands for dictating MOF architectures., This work was supported by the EU FP7 ERC-Co 615954, the Spanish MINECO (project PN MAT2015-65354-C2-1-R), and the Catalan AGAUR (project 2014 SGR 80). It was also funded by the CERCA Program/Generalitat de Catalunya. ICN2 acknowledges the support of MINECO through the Severo Ochoa Centers of Excellence Program, under Grant SEV-2013-0295. V.G. is grateful to the Generalitat de Catalunya for a Beatriu de Pinos fellowship (2014 BP-B 00155) (Marie Curie Fellowship, EU-funded project ITHACA).

Metal-organic frameworks (MOFs) are a class of novel nanoporous materials with many potential applications. Structural characterization is important because understanding the relationship between the properties of these industrially relevant materials and their structures allows one to develop new applications and improve current performance. Oxygen is one of the most important elements in many MOFs and exists in various forms. Ideally, 17O solid-state NMR (SSNMR) should be an excellent tool for characterizing various oxygen species. However, the major obstacles that prevent applying 17O SSNMR to MOF characterization are the synthetic effort needed for 17O isotopic enrichment and the associated high cost. In this work, we successfully prepared several prototypical 17O-enriched MOFs, including Zr-UiO-66, MIL-53(Al), CPO-27-Mg (or Mg-MOF-74), and microporous α-Mg3(HCOO)6. Depending on the target MOF, different isotopic enrichment methods were used to effectively incorporate 17O from 17O-enriched H2O. Using these 17O-enriched MOFs, we were able to acquire 17O SSNMR spectra at a magnetic field of 21.1 T. They provide distinct spectral signatures of various key oxygen species commonly seen in representative MOFs. We demonstrate that 17O SSNMR can be used to differentiate chemically and, under favorite circumstances, crystallographically nonequivalent oxygens and to follow the phase transitions. The synthetic approaches for preparation of 17O-enriched sample described in this paper are fairly simple and cost-effective.

International audience; The impact of surface deposition on cooperativity is explored in Au(111)-supported self-assembled metal-organic frameworks (MOFs) based on Fe(II) ions. Using a thermodynamic model, we first demonstrate that dimensionality reduction combined with deposition on a metal surface is likely to deeply enhance the spin-crossover cooperativity, going from gamma(3D) = 16 K for the bulk material to gamma(supp)(2D) = 386 K for its 2D supported derivative. On the basis of density functional theory, we then elucidate the electronic structure of a promising Fe-based MOF. A chemical strategy is proposed to turn a weakly interacting magnetic system into a strongly cooperative spin-crossover monolayer with gamma(Au(111))(MOF) = 83 K. These results open a promising route to the fabrication of cooperative materials based on SCO Fe(II) platforms.

Here we report the use of a pillaring strategy for the design and synthesis of three novel amide-functionalized metal-organic frameworks (MOFs), TMUs-22/-23/-24, isoreticular to the recently reported imine-functionalized TMU-6 and TMU-21 MOFs. An extensive study of their CO sorption properties and selectivity for CO over N, from single gas sorption isotherms to breakthrough measurements, revealed that not only the incorporation of amide groups but also their accessibility is crucial to obtain enhanced CO sorption and CO/N selectivity. Therefore, the MOF with more accessible amide groups (TMU-24) shows a CO/N selectivity value of ca. 10 (as revealed by breakthrough experiments), which is ca. 500% and 700% of the selectivity values observed for the other amide-containing (TMU-22 and TMU-23) and imine-containing (TMU-6 and TMU-21) MOFs., This work was supported by the Spanish MINECO (projects PN MAT2015-65354-C2-1-R and MAT2013-45008-P), the Catalan AGAUR (project 2014 SGR 80), and the ERC under the EU FP7 (ERC-Co 615954). I.I. and E.V.R.F. thank the MINECO for their RyC fellowships RYC-2010-06530 and RyC-2012-11427 and V.G. is grateful to the Generalitat de Catalunya for a Beatriu de Pinos Fellowship (2014 BP-B00155). ICN2 acknowledges the support of the Spanish MINECO through the Severo Ochoa Centers of Excellence Program, under Grant SEV-2013-0295. E.V.R.F. and J.S.A. acknowledge the Generalitat Valenciana for PROMETEOII/2014/004. Support of this investigation by Tarbiat Modares University is gratefully acknowledged.

PMCID: PMC4902134, The exceptional porosity of Metal-Organic Frameworks (MOFs) could be harnessed for countless practical applications. However, one of the challenges currently precluding the industrial exploitation of these materials is a lack of green methods for their synthesis. Since green synthetic methods obviate the use of organic solvents, they are expected to reduce the production costs, safety hazards and environmental impact typically associated with MOF fabrication. Herein we describe the stepwise optimisation of reaction parameters (pH, reagent concentrations and reaction time) for the room temperature, water-based synthesis of several members of the CPO-27/MOF-74-M series of MOFs, including ones made from Mg(ii), Ni(ii), Co(ii) and Zn(ii) ions. Using this method, we built MOFs with excellent BET surface areas and unprecedented Space-Time Yields (STYs). Employing this approach, we have synthesised CPO-27-M MOFs with record BET surface areas, including 1279 m2 g-1 (CPO-27-Zn), 1351 m2 g-1 (CPO-27-Ni), 1572 m2 g-1 (CPO-27-Co), and 1603 m2 g-1 (CPO-27-Mg). We anticipate that our method could be applied to produce CPO-27-Ni, -Mg, -Co and -Zn with STYs of 44 kg m-3 per day, 191 kg m-3 per day, 1462 kg m-3 per day and a record 18720 kg m-3 per day, respectively., This work was supported by the Spanish MINECO (project PN MAT2012-30994) and the EC (project FP7 ERC-Co 61594). I. I. acknowledges the Spanish MINECO for a Ramón y Cajal grant. ICN2 acknowledges support of the Spanish MINECO through the Severo Ochoa Centres of Excellence Program (Grant SEV-2013-0295).

The discovery of new methods for the post-synthesis modification of materials is essential in order to establish suitable strategies for the tuning of their properties in a rational manner. Here we present a series of single-crystal-to-single-crystal (SCSC) transformations for the flexible [Eu2(CIP)2(DMF)2(H2O)2] (UCY-8) [H3CIP = 5-(4-carboxybenzylideneamino)isophthalic acid] and rigid [Eu2(N-BDC)3(DMF)4] (EuN-BDC) (H 2N-BDC = 2-amino-1,4-benzene dicarboxylic acid) Metal-Organic Frameworks (MOFs) that involve the replacement of their coordinating solvent molecules by terminally ligating organic molecules with multiple functional groups including -OH, -SH, -NH- and -NH2 or their combinations, chelating ligands, and two different organic compounds. The capability of the flexible MOF, which contains small pores and channels (Cited By :18

Two new three-dimensional porous Zn(II)-based metal-organic frameworks, containing azine-functionalized pores, have been readily and quickly isolated via mechanosynthesis, by using a nonlinear dicarboxylate and linear N-donor ligands. The use of nonfunctionalized and methyl-functionalized N-donor ligands has led to the formation of frameworks with different topologies and metal-ligand connectivities and therefore different pore sizes and accessible volumes. Despite this, both metal-organic frameworks (MOFs) possess comparable BET surface areas and CO₂ uptakes at 273 and 298 K at 1 bar. The network with narrow and interconnected pores in three dimensions shows greater affinity for CO compared to the network with one-dimensional and relatively large pores-attributable to the more effective interactions with the azine groups.

Metal-organic frameworks (MOFs) are appealing candidates for use in energy harvesting and concentrating because of their high chromophore density and structural tunability. The ability to engineer electronic excitation energy transport pathways is of particular interest for designing energy harvesting materials. In this study, theoretical analysis was performed on energy transfer in MOFs that contain light absorbing ruthenium complexes that serve as hopping intermediates for energy transfer kinetics and energy trapping osmium complexes. We find that the excitation transport kinetics is well described by a Dexter (exchange) triplet-to-triplet energy transfer mechanism with multistep incoherent exciton hopping. The modeling combines ab initio electronic structure theory with kinetic network analysis. The sensitivity of Dexter mechanism energy transfer to framework structure establishes different kinds of energy transport paths in the different structures. For example, the mixed Ru/Os MOF structures described here establish one or three-dimensional hopping networks. As such, Dexter mechanism energy harvesting materials may be amenable to designing structures that can spatially direct exciton energy along specific pathways for energy delivery to reaction centers. © 2013 American Chemical Society. 117 43 22250 22259 Cited By :15

A series of new 3-D Ln3+ metal-organic frameworks (MOFs), which are based on the semi-rigid ligand H3CIP [H3CIP = 5-(4-carboxybenzylideneamino)isophthalic acid], [Ln2(CIP) 2(DMF)4-x(H2O)x] (Ln3+ = La3+, Ce3+, Pr3+, Sm3+, Eu 3+, Gd3+, Tb3+, Dy3+, Ho 3+ x = 0-2) are reported. Magnetic susceptibility data for selected compounds indicated the presence of antiferromagnetic interactions, while the photoluminescence properties of the MOFs revealed emission peaks that are red-shifted compared to the emission (405 nm) of the uncoordinated H 3CIP ligand, whereas the Eu3+ and Tb3+ analogues showed emission peaks typical of these lanthanide ions. Single-Crystal-to-Single-Crystal (SCSC) coordinating solvent exchange experiments with acetone and methanol for the Ce3+ analogue afforded compounds that are isostructural with the pristine material and contain one acetone and one water or 1.25 methanol and 0.75 water ligated molecules per Ce3+ respectively. The capability of activated Ce3+ MOF to absorb liquid MeOH was evaluated by means of 1H NMR spectroscopy. The results of the sorption experiments indicated a maximum absorption capacity of 96(2) mg g-1 and fast kinetics, while the sorbent is reusable and is also capable of highly selective sorption of MeOH over EtOH. Overall this work emphasizes the multifunctional nature of lanthanide MOFs and provides insight into the liquid-phase sorption of small organic molecules by such materials demonstrating their high potential as sorbents. © The Royal Society of Chemistry 2013. 1 16 5061 5069 Cited By :21