Structural Deterioration of Well‐Faceted MOFs upon H2S Exposure and Its Effect in the Adsorption Performance

The structural deterioration of archetypical, well‐faceted metal–organic frameworks (MOFs) has been evaluated upon exposure to an acidic environment (H2S). Experimental results show that the structural damage highly depends on the nature of the hybrid network (e.g., softness of the metal ions, hydrophilic properties, among others) and the crystallographic orientation of the exposed facets. Microscopy images show that HKUST‐1 with well‐defined octahedral (111) facets is completely deteriorated, ZIF‐8 with preferentially exposed (110) facets exhibits a large external deterioration with the development of holes or cavities in the mesoporous range, whereas UiO‐66‐NH2 with (111) exposed facets, and PCN‐250 with (100) facets does not reflect any sign of surface damage. Despite the selectivity in the external deterioration, X‐ray diffraction and gas adsorption measurements confirm that indeed all MOFs suffer an important internal deterioration, these effects being more severe for MOFs based on softer cations (e.g., Cu‐based HKUST‐1 and Fe‐based PCN‐250). These structural changes have inevitable important effects in the final adsorption performance for CO2 and CH4 at low and high pressures.JSA would like to acknowledge financial support from the MINECO (Project MAT2016-80285-p). I.I. and D.M. would like to acknowledge financial support from the Spanish MINECO (Project RTI2018-095622-B-100), and Catalan AGAUR (Project 2017 SGR 238), the ERC, under the EU-FP7 (ERC-Co 615954) and the CERCA Program/Generalitat de Catalunya. ICN2 is supported by the Severo Ochoa Program from the Spanish MINECO (Grant No. SEV-2017-0706)

Retrosynthetic Analysis Applied to Clip-off Chemistry : Synthesis of Four Rh(II)-Based Complexes as Proof-of-Concept

Clip-off Chemistry is a synthetic strategy that our group previously developed to obtain new molecules and materials through selective cleavage of bonds. Herein, we report recent work to expand Clip-off Chemistry by introducing into it a retrosynthetic analysis step that, based on virtual extension of the products through cleavable bonds, enables one to define the required precursor materials. As proof-of-concept, we have validated our new approach by synthesising and characterising four aldehyde-functionalised Rh(II)-based complexes: a homoleptic cluster; a cis-disubstituted paddlewheel cluster; a macrocycle; and a crown

Heterogeneous catalysts with programmable topologies generated by reticulation of organocatalysts into metal-organic frameworks : The case of squaramide

A well-established strategy to synthesize heterogeneous, metal-organic framework (MOF) catalysts that exhibit nanoconfinement effects, and specific pores with highly-localized catalytic sites, is to use organic linkers containing organocatalytic centers. Here, we report that by combining this linker approach with reticular chemistry, and exploiting three-dimensioanl (3D) MOF-structural data from the Cambridge Structural Database, we have designed four heterogeneous MOF-based catalysts for standard organic transformations. These programmable MOFs are isoreticular versions of pcu IRMOF-16, fcu UiO-68 and pillared-pcu SNU-8X, the three most common topologies of MOFs built from the organic linker p,p'-terphenyldicarboxylic acid (tpdc). To synthesize the four squaramide-based MOFs, we designed and synthesized a linker, 4,4'-((3,4-dioxocyclobut-1-ene-1,2-diyl)bis(azanedyil))dibenzoic acid (Sq_tpdc), which is identical in directionality and length to tpdc but which contains organocatalytic squaramide centers. Squaramides were chosen because their immobilization into a framework enhances its reactivity and stability while avoiding any self-quenching phenomena. Therefore, the four MOFs share the same organocatalytic squaramide moiety, but confine it within distinct pore environments. We then evaluated these MOFs as heterogeneous H-bonding catalysts in organic transformations: a Friedel-Crafts alkylation and an epoxide ring-opening. Some of them exhibited good performance in both reactions but all showed distinct catalytic profiles that reflect their structural differences

Clip-off Chemistry : Synthesis by Programmed Disassembly of Reticular Materials

Bond breaking is an essential process in chemical transformations and the ability of researchers to strategically dictate which bonds in a given system will be broken translates to greater synthetic control. Here, we report extending the concept of selective bond breaking to reticular materials in a new synthetic approach that we call Clip-off Chemistry. We show that bond-breaking in these structures can be controlled at the molecular level; is periodic, quantitative, and selective; is effective in reactions performed in either solid or liquid phases; and can occur in a single-crystal-to-single-crystal fashion involving the entire bulk precursor sample. We validate Clip-off Chemistry by synthesizing two topologically distinct 3D metal-organic frameworks (MOFs) from two reported 3D MOFs, and a metal-organic macrocycle from metal-organic polyhedra (MOP). Clip-off Chemistry opens the door to the programmed disassembly of reticular materials and thus to the design and synthesis of new molecules and materials. Clip-off Chemistry, a new approach to synthesizing molecules and materials based on the programmed de-reticulation and controlled etching at the molecular level in reticular materials, is introduced. Using this strategy, we have transformed two 3D metal-organic frameworks (MOFs) into two topologically distinct 3D MOFs, and one metal-organic polyhedra into a metal-organic macrocycle

Clip-off Chemistry : Synthesis by Programmed Disassembly of Reticular Materials

Bond breaking is an essential process in chemical transformations and the ability of researchers to strategically dictate which bonds in a given system will be broken translates to greater synthetic control. Here, we report extending the concept of selective bond breaking to reticular materials in a new synthetic approach that we call Clip-off Chemistry. We show that bond-breaking in these structures can be controlled at the molecular level; is periodic, quantitative, and selective; is effective in reactions performed in either solid or liquid phases; and can occur in a single-crystal-to-single-crystal fashion involving the entire bulk precursor sample. We validate Clip-off Chemistry by synthesizing two topologically distinct 3D metal-organic frameworks (MOFs) from two reported 3D MOFs, and a metal-organic macrocycle from metal-organic polyhedra (MOP). Clip-off Chemistry opens the door to the programmed disassembly of reticular materials and thus to the design and synthesis of new molecules and materials. Clip-off Chemistry, a new approach to synthesizing molecules and materials based on the programmed de-reticulation and controlled etching at the molecular level in reticular materials, is introduced. Using this strategy, we have transformed two 3D metal-organic frameworks (MOFs) into two topologically distinct 3D MOFs, and one metal-organic polyhedra into a metal-organic macrocycle

Clip-off Chemistry Applied to the Synthesis of Rh(II)-based Complexes via Rational Cleavage of Metal-Organic-Polyhedra

Les innovacions en mètodes sintètics han permès, al llarg de la història, descobrir nous materials i molècules. Cada nova reacció o metodologia sintètica no només ajuda a expandir el catàleg de materials i molècules sinó que també inspira noves maneres de pensar i innovar en estratègies sintètiques. Avui en dia, els mètodes sintètics més comuns consisteixen en la formació d'enllaços creant estructures més grans i complexes a partir d'unitats més petites. L'objectiu d'aquesta Tesi és explorar una nova metodologia sintètica anomenada "Clip-off-Chemistry". Aquest nou mètode sintètic consisteix a generar nous materials i molècules a través del trencament selectiu i racional d'enllaços covalents d'un material reticular proporcionant un control espacial precís de l'estructura final. Aquest trencament controlat d'enllaços es dona a escala molecular a través de l'ozonólisi d'enllaços dobles. En aquesta Tesi hem dut a terme la síntesi dels primers productes per "Clip-off Chemistry". Concretament ens hem centrat en el trencament de poliedres metal·loorgànics (MOPs) alliberant diversos compostos de coordinació.Las innovaciones en métodos sintéticos han permitido, a lo largo de la historia, descubrir nuevos materiales y moléculas. Cada nueva reacción o metodología sintética no solo ayuda a expandir el catálogo de materiales y moléculas, sino que también inspira nuevas maneras de pensar e innovar en estrategias sintéticas. Hoy en día, los métodos sintéticos más comunes consisten en la formación de enlaces creando estructuras más grandes y complejas a partir de unidades más pequeñas. El objetivo de esta Tesis es explorar una nueva metodología sintética denominada "Clip-off-Chemistry". Este nuevo método sintético consiste en generar nuevos materiales y moléculas a través de la rotura selectiva y racional de enlaces covalentes de un material reticular proporcionando un control espacial preciso de la estructura final. Esta rotura controlada de enlaces se da a escala molecular a través de la ozonólisis de enlaces dobles. En esta Tesis hemos llevado a cabo la síntesis de los primeros productos por "Clip-off Chemistry". Concretamente nos hemos centrado en la rotura de poliedros metalorgánicos (Rh-MOPs) liberando varios compuestos de coordinación.Innovations in chemical synthesis have historically led to the discovery of new materials and molecules. Each new reaction and methodology not only expand the accessible chemical space but also inspires researchers to explore novel ways of thinking and further innovate in the iterative design and preparation of new chemical targets. The most common synthetic approaches involve bottom-up strategies, where bonds link atoms or molecules to form larger compounds. In this Thesis, our aim is to explore a new approach to develop a novel synthetic methodology called Clip-off Chemistry. This new synthetic strategy aims to generate new materials and molecules by selectively and rationally cleaving covalent bonds in reticular materials, providing precise spatial control over the final structure. This controllable bond cleavage occurs at the molecular level through the ozonolysis of alkene bonds. Within this Thesis, our focus is to show the synthesis of the first products made using ";Clip-off Chemistry"; herein, through the cleavage of Rh-Metal-Organic Polyhedra (MOPs), releasing coordination compounds that would otherwise be inaccessible by direct synthesis

Metal- and covalent-organic framework mixed matrix membranes for CO2 separation : A perspective on stability and scalability

Membrane technology has attracted great industrial interest in carbon capture and separation owing to the merits of energy-efficiency, environmental friendliness and low capital investment. Conventional polymeric membranes for CO separation suffer from the trade-off between permeability and selectivity. Introducing porous fillers in polymers is one approach to enhance membrane separation performance. Metal-organic frameworks (MOFs), with ordered porous structure and diverse chemical functionalities, are promising fillers to prepare mixed matrix membranes (MMMs) for CO separation. However, the main issue of MOF based MMMs in industry is their stability and processability. This review analyses recent work on stable and scalable MOF based MMMs for CO separation. The typical stable MOFs, MOF-based MMMs and the scalable MOF synthesis are summarized. A large number of MOF-based MMM suffer from instability upon exposure to contaminants. For that reason, we also discuss the use of covalent organic frameworks (COFs) as an alternative to prepare MMMs for CO separation, considering their excellent stability and good compatibility with polymers. Finally, a brief conclusion and current challenges on obtaining scalable and stable MMMs are outlined. This review may provide some guidance for designing high performance MMMs for industrial CO capture and separation to help achieving carbon neutrality

Synthesis of the two isomers of heteroleptic Rh12L6L′6 metal-organic polyhedra by screening of complementary linkers

We have synthesised and characterised the two possible isomers of heteroleptic trigonal antiprismatic M12L6L′6 MOPs by screening reactions of rhodium acetate with different pairs of complementary dicarboxylate linkers. The resulting 12 new MOPs (eight of isomer A + four of isomer B) are microporous in the solid state, exhibiting Brunauer–Emmett–Teller (BET) surface areas as high as 770 m2 g−1.This work was supported by Spanish MINECO (project RTI2018-095622-B-I00) and “la Caixa” Foundation (ID 100010434; fellowship: LCF/BQ/PR20/11770011). ICN2 is supported by the Severo Ochoa programme from Spanish MINECO (Grant No. SEV-2017-0706).Peer reviewe

Heterogeneous catalysts with programmable topologies generated by reticulation of organocatalysts into metal-organic frameworks: the case of squaramide

Título del post-print: Rational design of heterogeneous catalysts with programmable topologies by reticulation of organocatalysts into metal-organic frameworks: the case of squaramideA well-established strategy to synthesize heterogeneous, metal-organic framework (MOF) catalysts that exhibit nanoconfinement effects, and specific pores with highly-localized catalytic sites, is to use organic linkers containing organocatalytic centers. Here, we report that by combining this linker approach with reticular chemistry, and exploiting three-dimensioanl (3D) MOF-structural data from the Cambridge Structural Database, we have designed four heterogeneous MOF-based catalysts for standard organic transformations. These programmable MOFs are isoreticular versions of pcu IRMOF-16, fcu UiO-68 and pillared-pcu SNU-8X, the three most common topologies of MOFs built from the organic linker p,p’-terphenyldicarboxylic acid (tpdc). To synthesize the four squaramide-based MOFs, we designed and synthesized a linker, 4,4’-((3,4‐dioxocyclobut‐1‐ene‐1,2‐diyl)bis(azanedyil))dibenzoic acid (Sq_tpdc), which is identical in directionality and length to tpdc but which contains organocatalytic squaramide centers. Squaramides were chosen because their immobilization into a framework enhances its reactivity and stability while avoiding any self-quenching phenomena. Therefore, the four MOFs share the same organocatalytic squaramide moiety, but confine it within distinct pore environments. We then evaluated these MOFs as heterogeneous H-bonding catalysts in organic transformations: a Friedel-Crafts alkylation and an epoxide ring-opening. Some of them exhibited good performance in both reactions but all showed distinct catalytic profiles that reflect their structural differencesThis work was supported by the Spanish MINECO (projects RTI2018-095622-B-I00 and RTI2018-095038-B-I00), the Catalan AGAUR (project 2017 SGR 238), the ERC under the EU FP7 (ERC−Co 615954), European Union’s Horizon 2020 research and innovation program under grant agreement No. 685727, and European Structural Funds (S2018/NMT-4367). 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

Clip-off Chemistry: Synthesis by Programmed Disassembly of Reticular Materials**

Bond breaking is an essential process in chemical transformations and the ability of researchers to strategically dictate which bonds in a given system will be broken translates to greater synthetic control. Here, we report extending the concept of selective bond breaking to reticular materials in a new synthetic approach that we call Clip-off Chemistry. We show that bond-breaking in these structures can be controlled at the molecular level; is periodic, quantitative, and selective; is effective in reactions performed in either solid or liquid phases; and can occur in a single-crystal-to-single-crystal fashion involving the entire bulk precursor sample. We validate Clip-off Chemistry by synthesizing two topologically distinct 3D metal-organic frameworks (MOFs) from two reported 3D MOFs, and a metal-organic macrocycle from metal-organic polyhedra (MOP). Clip-off Chemistry opens the door to the programmed disassembly of reticular materials and thus to the design and synthesis of new molecules and materials.This work has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 101019003, the Spanish MINECO (projects RTI2018-095622-B-I00 and PID2019-106403RB-I00) and the Catalan AGAUR (project 2017 SGR 238). It was also funded by the CERCA Programme/Generalitat de Catalunya. ICN2 is supported by the Severo Ochoa programme from the Spanish MINECO (Grant No. SEV-2017-0706). F.G. acknowledges funding from the Spanish Research Agency (AEI, CTQ2017-87262-R, EUR2019-103824). The project that generated these results received support from a fellowship (LCF/BQ/PR20/11770011) of the “la Caixa” Foundation (ID 100010434). Y.Y. acknowledges the China Scholarship Council for scholarship support