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Shapeshifting materials have captured the imagination of researchers for their myriad potential applications, yet their practical development remains challenging. These materials operate by mechanical actuation: their structural responses to external stimuli generate mechanical work. Here, we review progress on the use of flexible metal–organic frameworks (MOFs) in composite actuators that shapeshift in a controlled fashion. We highlight the dynamic behaviour of flexible MOFs, which are unique among materials, even other porous ones, and introduce the concept of propagation, which involves the efficient transmission of flexible MOF deformations to the macroscale. Furthermore, we explain how researchers can observe, measure, and induce such effects in MOF composites. Next, we review pioneering first-generation MOF-composite actuators that shapeshift in response to changes in humidity, temperature, pressure, or to other stimuli. Finally, we allude to recent developments, identify remaining R & D hurdles, and suggest future directions in this field. [ABSTRACT FROM AUTHOR]

The activity of catalytic nanoparticles is strongly dependent on their surface chemistry, which controls colloidal stability and substrate diffusion toward catalytic sites. In this work, we studied how the outer surface chemistry of nanostructured Rh(II)‐based metal‐organic cages or polyhedra (Rh‐MOPs) impacts their performance in homogeneous catalysis. Specifically, through post‐synthetic coordination of aliphatic imidazole ligands onto the exohedral Rh(II) axial sites of Rh‐MOPs, we solubilized a cuboctahedral Rh‐MOP in dichloromethane, thereby enabling its use as a homogeneous catalyst. We demonstrated that the presence of the coordinating ligand on the surface of the Rh‐MOP does not hinder its catalytic activity in styrene aziridination and cyclopropanation reactions, thanks to the dynamic Rh‐imidazole coordination bond. Finally, we used similar ligand exchange post‐synthetic reactions to develop a ligand‐mediated approach for precipitating the Rh‐MOP catalyst, facilitating the recovery and reuse of Rh‐MOPs as homogeneous catalysts. [ABSTRACT FROM AUTHOR]

Abstract: An overview of the work that have been developed over the last six years in our group on the use of polychlorotriphenylmetyl radicals (PTM) functionalized by carboxylic groups to access to purely organic/molecular magnetic materials is reported. From the seminal work on the monocarboxylic PTM (Section 2), of great importance to determine both the ability of these molecules to form intermolecular H-bonds and the nature of the intermolecular interactions mediated through the resulting supramolecular motifs, we will move to the self-assembly of PTM radicals functionalized with two and three carboxylic groups (Section 3). In those cases, the self-assembly of the paramagnetic units yield robust and porous magnetic structures, associating in some cases magnetic ordering to the latest remarkable characteristics. The last part of the review will present the latest results obtained with the idea to increase both the structural and magnetic dimensionality in purely organic PTM-based materials using a PTM radical functionalized by six carboxylic groups (Section 4). New trends and challenges for this research line, concerning the design and synthesis of new PTM radicals, as well as the obtaining of PTM based sensors or multifunctional materials will be presented in the concluding section (Section 5). [Copyright &y& Elsevier]

We report the synthesis, crystal structures, and magnetic properties of a series of mononuclear, metal-radical complexes with first-row transition-metal ions using a new class of radical-based ligands, the polychlorinated triphenylmethyl (PTM) radicals. Crystal structures of three new PTM-based complexes of general formula M(PTMMC)2(py)4-x(H2O)x [PTMMC = PTM radical functionalized at the para position with one carboxylic group; M = Zn(II), x = 2 (1); M = Ni(II), x = 1 (2); M = Co(II), x = 1 (3)] show similar molecular structures in which mononuclear complexes are formed by an octahedral metal ion coordinated by two monodentated PTMMC units. From a magnetic point of view, these similar configurations describe a quasilinear, trimeric magnetic model (PTMMC-M(II)-PTMMC), in which the metal [Ni(II) or Co(II)]-radical magnetic-exchange coupling constants have been determined for the first time. In all of these complexes, the temperature dependence of the magnetic susceptibility reveals moderate antiferromagnetic-exchange coupling constants between the PTMMC radicals and Ni(II) (2J/kB = -47.1 K) and Co(II) ions (2J/kB = -15.2 K) based on the exchange Hamiltonian H = -2JSM(Srad1 + Srad2). [ABSTRACT FROM AUTHOR]

The treatment of α-H-p-H-PTM (PTM = polychlorotriphenylmethane) with oleum 65% followed by deprotonation and oxidation leads to the isolation of a novel pure organic radical PTMSO3H·3H2O·0.5hexane (2). The X-ray diffraction of 2 reveals a layered structure with disordered H2O molecules between facing sulfonic acid groups. We have explored the coordination abilities of the sulfonate derivative using different metals. The treatment of 2 with mild bases yields the sulfonate radical PTMSO3Na·H2O (3). On the other hand, the new compound [Cu(py)2(H2O)4]-(PTMSO3)2·2H2O·2EtOH (4) has been crystallized using CuII as the metallic counterion in the presence of pyridine. The structure reveals a solvent-separated ion-pair-type compound, with no direct coordination of the metal ion with the sulfonate group, and the formation of organic layers between layers of transition metal complexes. This situation has been overcome by favoring the stabilization of the sulfonate group over the CuII center by changing the pyridine ligand to cyclam. This has led to compound [Cu(cyclam)](PTMSO3)2·6EtOH (5a), in which the sulfonate group acts as a monodentate axial ligand for the CuII center. We have observed a single-to-single crystal rearrangement from 5a to [Cu(cyclam)](PTMSO3)2 (5b) because of the loss of the solvent of crystallization, without significant modification of the metal coordination environment. All species have been structurally and magnetically characterized, and the magnetic coupling between the organic radicals and the metal paramagnetic centers is discussed. [ABSTRACT FROM AUTHOR]

Directed assembly of nanoscale building blocks such as single- walled carbon nanotubes (SWNTs) into desired architectures is a major hurdle for a broad range of basic research and technological applications (e.g., electronic devices and sensors). Here we demonstrate a parallel assembly process that allows one to simultaneously position, shape, and link SWNTs with sub-100-nm resolution. Our method is based on the observation that SWNTs are strongly attracted to COOH-terminated self-assembled monolayers (COOH-SAMs) and that SWNTs with lengths greater than the dimensions of a COOH-SAM feature will align along the boundary between the COOH-SAM feature and a passivating CH3-terminated SAM. By using nanopatterned affinity templates of 16-mercapto-hexadecanonic acid, passivated with 1-octadecanethiol, we have formed SWNT dot, ring, arc, letter, and even more sophisticated structured thin films and continuous ropes. Experiment and theory (Monte Carlo simulations) suggest that the COOH-SAMs localize the solvent carrying the nanotubes on the SAM features, and that van der Waals interactions between the tubes and the COOH-rich feature drive the assembly process. A mathematical relationship describing the geometrically weighted interactions between SWNTs and the two different SAMs required to overcome solvent- SWNT interactions and effect assembly is provided. [ABSTRACT FROM AUTHOR]

Abstract: In this review, we will give a short overview of a new type of magnetic nanoporous molecular materials developed in our group, based on the use of open-shell organic polychlorotriphenylmethyl (PTM) radicals as building-blocks. First, from a geometrical point of view, PTMDC and PTMTC acidic radicals can be considered expanded versions of the isophtalic and trimesic acid molecules, respectively, where the benzene-1,3-diyl and benzene-1,3,5-triyl units has been replaced by an sp2 hybridized carbon atom decorated with two or three 4-substituted 2,3,5,6-tetrachlorophenyl rings. Therefore, according with their related trigonal symmetries and functionalities, PTMDC and PTMTC radicals are expected to yield similar open-frameworks structures than isophtalic and trimesic acid. Second, polychlorinated triphenylmethyl radicals have their central carbon atom, where most of the spin density is localized, sterically shielded by the six bulky chlorine atoms that increase astonishingly its lifetime and thermal and chemical stabilities. Furthermore, the intrinsic molecular bulkiness and rigidity of this family of radicals is also expected to prevent a close packing of molecular units in the solid state. And third, the monocarboxylic PTMMC radical has allowed to confirm the excellent conditions of PTM radicals to magnetically interact between them and with transition metal ions through the carboxylic groups. Indeed, a recently reported family of monomeric complexes using PTMMC radical has confirmed the feasibility of this type of carboxylic-substituted radicals to magnetically interact with metal ions (Fig. 1). Thus, in this review, we will focus our attention to the recent results on the use of carboxylic-substituted PTM radicals for the obtaining of the first examples of metal-organic and purely organic molecular radical-based materials with combined interesting porosity characteristics and magnetic properties. To cite this article: D. Maspoch et al., C. R. Chimie 8 (2005) . [Copyright &y& Elsevier]

A trinuclear MnII cluster based on the versatile polychlorinated triphenylmethyl carboxylic radical ligand has been characterized by X-ray crystallography and magnetic measurements, representing a rare example of a MnII trinuclear linear structure with six open-shell ligands. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) possess intrinsic nanoscale pores, limiting mass transport and impacting their utility in many applications, such as catalysis, supercapacitors, and gas storage, demanding efficient diffusion throughout the material. Hierarchical porous structures, integrating larger macropores with inherent micro‐/meso‐pores, facilitate rapid mass transport. Recently, the fabrication of aerogel monoliths is reported exclusively from imine‐linked COFs, offering flexibility in aerogel composition. However, challenges in synthesizing robust β‐ketoenamine‐based COFs with comparable surface areas prompted innovative synthetic approaches. Leveraging the dynamic nature of COF bonds, in this work efficient monomer exchange from imine to partially β‐ketoenamine‐linked COFs within the gel phase is demonstrated. These aerogels can be transformed into electrodes using the compression technique. The new flexible electrodes‐based β‐ketoenamine‐linked COF composites with C super P exhibit superior durability and redox activity. Through supercapacitor assembly, the β‐ketoenamine‐linked COF electrodes outperform their imine‐based counterparts, showcasing enhanced capacitance (88 mF cm−2) and stability at high current densities (2.0 mA cm−2). These findings underscore the promise of β‐ketoenamine‐linked COFs for pseudocapacitor energy storage applications. [ABSTRACT FROM AUTHOR]

Aerogels are porous ultralight materials known for their high porosity, wide range of pore sizes, low density, and good macroscopic mechanical properties, all of which make them promising candidates for shaped adsorbents, catalysts, and insulators, among other applications. Here, this work reports a new approach that enables both the formation of modular aerogels, via dynamic covalent chemistry, and their post‐synthetic modification, via coordination chemistry. To demonstrate this strategy, this work first polymerizes porous amino‐functionalized Rh(II)‐based metal‐organic polyhedra (MOPs) with aldehydes, which afforded robust imine‐gel networks that is then converted into aerogels. Next, this work functionalizes these aerogels through the coordination of ligands on the axial site of Rh(II) paddlewheels of the MOP. Interestingly, in this chemistry, the local changes in the coordination site of the MOPs are transferred to the overall aerogel, thereby altering its macroscopic physicochemical properties. Importantly, this feature enables the synthesis of optimized adsorbents tailored to specific guests, as this work demonstrates through a series of experiments using ligands of different electrostatic and hydrophobic characters. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have made inroads in diverse chemical sectors due to the essentially limitless combination of building units and the ability to post-synthetically modify their pore chemistry at the molecular level. The crystalline nature of MOFs permits the use of single crystal X-ray diffraction (SCXRD) to obtain crystallographic snapshots of these transformations, providing invaluable information into the unorthodox chemistry that MOFs can potentially offer. This highlight article aims to provide the reader with the most recent milestones in the use of SCXRD as a vanguard technique to connect molecular-level pore engineering of MOFs with new application fields hitherto unexplored. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The surface chemistry of Metal–Organic Polyhedra (MOPs) is crucial to their physicochemical properties because it governs how they interact with external substances such as solvents, synthetic organic molecules, metal ions, and even biomolecules. Consequently, the advancement of synthetic methods that facilitate the incorporation of diverse functional groups onto MOP surfaces will significantly broaden the range of properties and potential applications for MOPs. This study describes the use of copper(I)‐catalysed, azide–alkyne cycloaddition (CuAAC) click reactions to post‐synthetically modify the surface of alkyne‐functionalised cuboctahedral MOPs. To this end, a novel Rh(II)‐based MOP with 24 available surface alkyne groups was synthesised. Each of the 24 alkyne groups on the surface of the "clickable" Rh‐MOP can react with azide‐containing molecules at room temperature, without compromising the integrity of the MOP. The wide substrate catalogue and orthogonal nature of CuAAC click chemistry was exploited to densely functionalise MOPs with diverse functional groups, including polymers, carboxylic and phosphonic acids, and even biotin moieties, which retained their recognition capabilities once anchored onto the surface of the MOP. [ABSTRACT FROM AUTHOR]

This article presents the first example of a purely organic magnetic and robust nanoporous lattice based on the supramolecular arrangement of an open-shell molecule, the dicarboxylic perchiorinated triphenyimethyl radical. The use of this free radical as a supramolecular synthon has several advantages as it exhibits a high thermal and chemical stability and its trigonal symmetry provides a typical template for getting channels held together by hydrogen bonds through the two carboxylic groups. Crystallization of the dicarboxylic radical generates the pure organic radical open-framework material, combining large hydrophobic nanocavities with hydrophilic windows along with magnetic characteristics. Self-assembly of radical generates a paramagnetic open-framework structure with one-dimensional nanochannels formed by narrowed polar windows and large hydrophobic nanocontainers.

Metal–organic frameworks (MOFs) based on high-connected nets are generally very attractive due to their combined robustness and porosity. Here, we describe the synthesis of BCN-348, a new high-connected Zr-MOF built from an 8-connected (8-c) cubic Zr-oxocluster and an 8-c organic linker. BCN-348 contains a minimal edge-transitive 3,4,8-c eps net, and combines mesoporosity with thermal and hydrolytic stability. Encouraging results from preliminary studies on its use as a catalyst for hydrolysis of a nerve-agent simulant suggest its potential as an agent for detoxification of chemical weapons and other pernicious compounds. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) possess high CO2 adsorption properties and are considered to be a promising candidate for the electrochemical carbon dioxide reduction reaction (eCO2RR). However, their insufficient selectivity and current density constrain their further exploration in the eCO2RR. In this work, by introducing a very small proportion of 2,5-dihydroxyterephthalic acid (DOBDC) into ZIF-8, a surface modified ZIF-8-5% catalyst was synthesized by a post-modification method, exhibiting enhanced selectivity (from 56% to 79%) and current density (from −4 mA cm−2 to −10 mA m−2) compared to ZIF-8. Density functional theory (DFT) calculations further demonstrate that the boosted eCO2RR performance on ZIF-8-5% could be attributed to the improved formation of the *COOH intermediate stemming from successful DOBDC surface modification. This work opens a new path for improving the catalytic properties of MOFs via their surface modification. [ABSTRACT FROM AUTHOR]

Self-assembly of colloidal particles into ordered superstructures enables the development of novel advanced materials for diverse applications such as photonics, electronics, sensing, energy conversion, energy storage, diagnosis, drug or gene delivery, and catalysis. Recently, polyhedral metal–organic framework (MOF) particles have been proposed as promising colloidal particles to form ordered superstructures, based on their colloidal stability, size-tunability, rich polyhedral shapes, porosity and multifunctionality. In this review, we present a comprehensive overview of strategies for the self-assembly of colloidal MOF particles into ordered superstructures of different dimensionalities, highlighting some of their properties and applications, and sharing thoughts on the self-assembly of MOF particles. [ABSTRACT FROM AUTHOR]

Increasing the chemical complexity of metal–organic cages (MOCs) or polyhedra (MOPs) demands control over the simultaneous organization of diverse organic linkers and metal ions into discrete caged structures. Herein, we show that a pre-assembled complex of the archetypical cuboctahedral MOP can be used as a template to replicate such caged structure, one having a "triblock Janus-type" configuration that is both heterometallic and heteroleptic. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Water pollution threatens human and environmental health worldwide. Thus, there is a pressing need for new approaches to water purification. Herein, we report a novel supramolecular strategy based on the use of a metal‐organic polyhedron (MOP) as a capture agent to remove nitrogenous organic micropollutants from water, even at very low concentrations (ppm), based exclusively on coordination chemistry at the external surface of the MOP. Specifically, we exploit the exohedral coordination positions of RhII‐MOP to coordinatively sequester pollutants bearing N‐donor atoms in aqueous solution, and then harness their exposed surface carboxyl groups to control their aqueous solubility through acid/base reactions. We validated this approach for removal of benzotriazole, benzothiazole, isoquinoline, and 1‐napthylamine from water. [ABSTRACT FROM AUTHOR]

Multidrug‐resistant bacteria have become a global health problem for which new prophylactic strategies are now needed, including surface‐coatings for hospital spaces and medical equipment. This work reports the preparation and functional validation of a metal‐organic framework (MOF) based composite for the triggered controlled release of iodine, an antimicrobial element that does not generate resistance. It comprises beads of the iodophilic MOF UiO‐66 containing encapsulated gold nanorods (AuNRs) coated with a silica shell. Irradiation of the AuNRs with near‐infrared light (NIR) provokes a photothermal effect and the resultant heat actively liberates the iodine. After validating the performance of this composite, it is integrated into a polymer for the development of antibacterial films. This work assesses the adsorption of iodine into these composite films, as well as its passive long‐term release and active light‐triggered. Finally, this work validates the antibacterial activity of the composite films in vitro against gram‐positive and gram‐negative bacteria. The findings will surely inform the development of new prophylactic treatments. [ABSTRACT FROM AUTHOR]

Metal–organic polyhedra (MOPs) are a subclass of coordination cages that can adsorb and host species in solution and are permanently porous in solid‐state. These characteristics, together with the recent development of their orthogonal surface chemistry and the assembly of more stable cages, have awakened the latent potential of MOPs to be used as building blocks for the synthesis of extended porous networks. This review article focuses on exploring the key developments that make the extension of MOPs possible, highlighting the most remarkable examples of MOP‐based soft materials and crystalline extended frameworks. Finally, the article ventures to offer future perspectives on the exploitation of MOPs in fields that still remain ripe toward the use of such unorthodox molecular porous platforms. [ABSTRACT FROM AUTHOR]

Supraparticles are spherical colloidal crystals prepared by confined self‐assembly processes. A particularly appealing property of these microscale structures is the structural color arising from interference of light with their building blocks. Here, we assemble supraparticles with high structural order that exhibit coloration from uniform, polyhedral metal–organic framework (MOF) particles. We analyse the structural coloration as a function of the size of these anisotropic building blocks and their internal structure. We attribute the angle‐dependent coloration of the MOF supraparticles to the presence of ordered, onion‐like layers at the outermost regions. Surprisingly, even though different shapes of the MOF particles have different propensities to form these onion layers, all supraparticle dispersions show well‐visible macroscopic coloration, indicating that local ordering is sufficient to generate interference effects. [ABSTRACT FROM AUTHOR]

Supraparticles are spherical colloidal crystals prepared by confined self‐assembly processes. A particularly appealing property of these microscale structures is the structural color arising from interference of light with their building blocks. Here, we assemble supraparticles with high structural order that exhibit coloration from uniform, polyhedral metal–organic framework (MOF) particles. We analyse the structural coloration as a function of the size of these anisotropic building blocks and their internal structure. We attribute the angle‐dependent coloration of the MOF supraparticles to the presence of ordered, onion‐like layers at the outermost regions. Surprisingly, even though different shapes of the MOF particles have different propensities to form these onion layers, all supraparticle dispersions show well‐visible macroscopic coloration, indicating that local ordering is sufficient to generate interference effects. [ABSTRACT FROM AUTHOR]

Demand continues for processing methods to shape covalent organic frameworks (COFs) into macroscopic objects that are needed for their practical applications. Herein, a simple compression method to prepare large‐scale, free‐standing homogeneous and porous imine‐based COF‐membranes with dimensions in the centimeter range and excellent mechanical properties is reported. This method entails the compression of imine‐based COF‐aerogels, which undergo a morphological change from an elastic to plastic material. The COF‐membranes fabricated upon compression show good performances for the separation of gas mixtures of industrial interest, N2/CO2 and CH4/CO2. It is believed that the new procedure paves the way to a broader range of COF‐membranes. [ABSTRACT FROM AUTHOR]

Metal–organic polyhedra (MOPs) are discrete, intrinsically-porous architectures that operate at the molecular regime and, owing to peripheral reactive sites, exhibit rich surface chemistry. Researchers have recently exploited this reactivity through post-synthetic modification (PSM) to generate specialised molecular platforms that may overcome certain limitations of extended porous materials. Indeed, the combination of modular solubility, orthogonal reactive sites, and accessible cavities yields a highly versatile molecular platform for solution to solid-state applications. In this feature article, we discuss representative examples of the PSM chemistry of MOPs, from proof-of-concept studies to practical applications, and highlight future directions for the MOP field. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A novel, versatile pen-type lithography-based methodology was developed to control the growth of HKUST-1 crystals on surfaces by direct delivery of femtoliter droplets containing both inorganic and organic building block precursors. This approach shows that through the use of surfaces with low wettability it is possible to control the crystallization of a single submicrometer metal-organic framework crystal at a desired location on a surface. [ABSTRACT FROM AUTHOR]

We report the synthesis, crystal structures, and magnetic properties of two new metal-radical chains built up tram a new class at organic radical-based ligands, the polychlorinated triphenylmethyl (PTM) radicals. Crystal structures of two new 1D coordination polymers, [Cu2(PTMDC)2(py)5(∙3EtOH))-3EtOH (1) and [Co2(PTMDC)2(DMF)2(H2O)6]5DMF (2) (where PTMDC is a PTM radical functionalized with two carboxylic groups), show similar chain-like structures, in which each of the PTMDC radicals are connecting two Cu(ll) or Co(ll) metal ions. Therefore, from a magnetic point of view, both structures describe a magnetic chain model based on the PTMDC-M(ll) unit. In this manuscript, the magnetic exchange coupling constants between both metal ions and the bridging PTM radicals have been determined. In both cases, the temperature dependence of the magnetic susceptibility reveals antiferromagnetic exchange coupling constants between the PTMDC radicals and Cu(ll) (J/kB -42 K) and Co(ll) (J/kB = -14.6 K) ions based on the exchange Hamiltonian H = -JΣSA1SA1-1. [ABSTRACT FROM AUTHOR]

Abstract: Two europium (III) complexes (3 and 4) have been obtained reacting europium (III) nitrate and two polychlorotriphenylmethyl radicals properly functionalized with one (PTMMC−, 1) and six (PTMHC6−, 2) carboxylate groups, respectively. While complex 3 reveals a lamellar polar–apolar separated ion pair structure alternating PTM-based bilayers with nonaaquaeuropium cations ([Eu(H2O)9](PTMMC)3(PTMMCH)3 ·7H2O·6EtOH), complex 4 shows a one-dimensional chain-like structure with formula [Eu2(PTMHC)(H2O)13]·16H2O·EtOH. Magnetic properties of both complexes were studied in the 2–300K range, and show the presence of weak inter-radical antiferromagnetic interactions below 5K. [Copyright &y& Elsevier]

This article describes novel phase-separation behavior by a binary mixture of alkanethiols when deposited onto a gold surface using micro- and nanodeposition tools, such as microcontact printing (μCP) and dip-pen nanolithography (DPN). This behavior is significantly different than that observed in the bulk. We demonstrate this behavior using three model compounds: 16-mercaptohexadecanoic acid (MHA), 1-octadecanethiol (ODT), and CF3(CF2)11(CH2)2SH (PFT). The identity of the resulting segregated structure is confirmed by lateral force microscopy (LFM) and by selective metal-organic coordination chemistry. Importantly, this phenomenon can be exploited to print sub-100 nm wide alkanethiol lines via conventional μCP and to form sub-15 nm features using DPN, which is below the ultimate resolution of both these techniques. We also demonstrate that these nanopatterned materials can serve as templates for constructing more complex architectures. [ABSTRACT FROM AUTHOR]

The use of covalent organic frameworks (COFs) in practical applications demands shaping them into macroscopic objects, which remains challenging. Herein, we report a simple three‐step method to produce COF aerogels, based on sol‐gel transition, solvent‐exchange, and supercritical CO2 drying, in which 2D imine‐based COF sheets link together to form hierarchical porous structures. The resultant COF aerogel monoliths have extremely low densities (ca. 0.02 g cm−3), high porosity (total porosity values of ca. 99 %), and mechanically behave as elastic materials under a moderate strain (<25–35 %) but become plastic under greater strain. Moreover, these COF aerogels maintain the micro‐ and meso‐porosity of their constituent COFs, and show excellent absorption capacity (e.g. toluene uptake: 32 g g−1), with high removal efficiency (ca. 99 %). The same three‐step method can be used to create functional composites of these COF aerogels with nanomaterials. [ABSTRACT FROM AUTHOR]

The use of covalent organic frameworks (COFs) in practical applications demands shaping them into macroscopic objects, which remains challenging. Herein, we report a simple three‐step method to produce COF aerogels, based on sol‐gel transition, solvent‐exchange, and supercritical CO2 drying, in which 2D imine‐based COF sheets link together to form hierarchical porous structures. The resultant COF aerogel monoliths have extremely low densities (ca. 0.02 g cm−3), high porosity (total porosity values of ca. 99 %), and mechanically behave as elastic materials under a moderate strain (<25–35 %) but become plastic under greater strain. Moreover, these COF aerogels maintain the micro‐ and meso‐porosity of their constituent COFs, and show excellent absorption capacity (e.g. toluene uptake: 32 g g−1), with high removal efficiency (ca. 99 %). The same three‐step method can be used to create functional composites of these COF aerogels with nanomaterials. [ABSTRACT FROM AUTHOR]

The physicochemical similarity of isomers makes their chemical separation through conventional techniques energy intensive. Herein, we report that, instead of using traditional encapsulation‐driven processes, steric hindrance in metal coordination on the outer surface of RhII‐based metal–organic polyhedra (Rh‐MOPs) can be used to separate pyridine‐based regioisomers via liquid–liquid extraction. Through molecular dynamics simulations and wet experiments, we discovered that the capacity of pyridines to coordinatively bind to Rh‐MOPs is determined by the positions of the pyridine substituents relative to the pyridine nitrogen and is influenced by steric hindrance. Thus, we exploited the differential solubility of bound and non‐bound pyridine regioisomers to engineer liquid–liquid self‐sorting systems. As a proof of concept, we separated four different equimolecular mixtures of regioisomers, including a mixture of the industrially relevant compounds 2‐chloropyridine and 3‐chloropyridine, isolating highly pure compounds in all cases. [ABSTRACT FROM AUTHOR]

The physicochemical similarity of isomers makes their chemical separation through conventional techniques energy intensive. Herein, we report that, instead of using traditional encapsulation‐driven processes, steric hindrance in metal coordination on the outer surface of RhII‐based metal–organic polyhedra (Rh‐MOPs) can be used to separate pyridine‐based regioisomers via liquid–liquid extraction. Through molecular dynamics simulations and wet experiments, we discovered that the capacity of pyridines to coordinatively bind to Rh‐MOPs is determined by the positions of the pyridine substituents relative to the pyridine nitrogen and is influenced by steric hindrance. Thus, we exploited the differential solubility of bound and non‐bound pyridine regioisomers to engineer liquid–liquid self‐sorting systems. As a proof of concept, we separated four different equimolecular mixtures of regioisomers, including a mixture of the industrially relevant compounds 2‐chloropyridine and 3‐chloropyridine, isolating highly pure compounds in all cases. [ABSTRACT FROM AUTHOR]

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 2 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 2 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 2 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 2 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 2 capture and separation to help achieving carbon neutrality. [Display omitted] • Metal organic frameworks (MOFs) in a mixed matrix membrane (MMM) can increase CO 2 selectivity, but are not commercial yet. • Stability of MOF particles is challenging when water, sulphuric compounds or ammonia are in the feed gas. • Stability of MOF-based MMM has insufficiently studied for durations > 1000 h, while required for industrial application. • Covalent organic frameworks (COFs) are a more stable alternative for CO 2 separation with MMMs. • Manufacturing of MOFs is possible at kg-scale, where particle size (∼100 nm) is crucial for thin film composite structures. [ABSTRACT FROM AUTHOR]

The use of covalent organic frameworks (COFs) in practical applications demands shaping them into macroscopic objects, which remains challenging. Herein, we report a simple three‐step method to produce COF aerogels, based on sol‐gel transition, solvent‐exchange, and supercritical CO2 drying, in which 2D imine‐based COF sheets link together to form hierarchical porous structures. The resultant COF aerogel monoliths have extremely low densities (ca. 0.02 g cm−3), high porosity (total porosity values of ca. 99 %), and mechanically behave as elastic materials under a moderate strain (<25–35 %) but become plastic under greater strain. Moreover, these COF aerogels maintain the micro‐ and meso‐porosity of their constituent COFs, and show excellent absorption capacity (e.g. toluene uptake: 32 g g−1), with high removal efficiency (ca. 99 %). The same three‐step method can be used to create functional composites of these COF aerogels with nanomaterials. [ABSTRACT FROM AUTHOR]

Use of preformed metal‐organic polyhedra (MOPs) as supermolecular building blocks (SBBs) for the synthesis of metal‐organic frameworks (MOFs) remains underexplored due to lack of robust functionalized MOPs. Herein we report the use of polycarboxylate cuboctahedral RhII‐MOPs for constructing highly‐connected MOFs. Cuboctahedral MOPs were functionalized with carboxylic acid groups on their 12 vertices or 24 edges through coordinative or covalent post‐synthetic routes, respectively. We then used each isolated polycarboxylate RhII‐MOP as 12‐c cuboctahedral or 24‐c rhombicuboctahedral SBBs that, upon linkage with metallic secondary building units (SBUs), afford bimetallic highly‐connected MOFs. The assembly of a pre‐synthesized 12‐c SBB with a 4‐c paddle‐wheel SBU, and a 24‐c SBB with a 3‐c triangular CuII SBU gave rise to bimetallic MOFs having ftw (4,12)‐c or rht (3,24)‐c topologies, respectively. [ABSTRACT FROM AUTHOR]

Use of preformed metal‐organic polyhedra (MOPs) as supermolecular building blocks (SBBs) for the synthesis of metal‐organic frameworks (MOFs) remains underexplored due to lack of robust functionalized MOPs. Herein we report the use of polycarboxylate cuboctahedral RhII‐MOPs for constructing highly‐connected MOFs. Cuboctahedral MOPs were functionalized with carboxylic acid groups on their 12 vertices or 24 edges through coordinative or covalent post‐synthetic routes, respectively. We then used each isolated polycarboxylate RhII‐MOP as 12‐c cuboctahedral or 24‐c rhombicuboctahedral SBBs that, upon linkage with metallic secondary building units (SBUs), afford bimetallic highly‐connected MOFs. The assembly of a pre‐synthesized 12‐c SBB with a 4‐c paddle‐wheel SBU, and a 24‐c SBB with a 3‐c triangular CuII SBU gave rise to bimetallic MOFs having ftw (4,12)‐c or rht (3,24)‐c topologies, respectively. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Type 1 diabetes (T1D) is an autoimmune disease caused by the destruction of insulin-producing cells. Due to the ability of apoptotic cells clearance to induce tolerance, we previously generated liposomes rich in phophatidylserine (PS) –a feature of apoptotic cells– loaded with insulin peptides to mimic apoptotic beta-cells. PS-liposomes arrested autoimmunity in experimental T1D through the induction of tolerance. The aim of this study was to investigate the potential of several peptides from different T1D autoantigens encapsulated in (PS)-liposomes for T1D prevention and to assess its safety. T1D autoantigens (Insulin, C-peptide, GAD65 and IA2) were encapsulated in PS-liposomes. Liposomes were administered to the 'gold-standard' model for the study of autoimmune T1D, the Non-Obese Diabetic mouse, that spontaneously develop the disease. Safety and toxicity of liposomes were also determined. Only PS-liposomes encapsulating insulin peptides decrease T1D incidence in the Non-Obese Diabetic mouse model. Disease prevention correlates with a decrease in the severity of the autoimmune islet destruction driven by leukocytes. PS-liposomes neither showed toxic effect nor secondary complications. Among the here referred autoantigens, insulin peptides are the best candidates to be encapsulated in liposomes, like an artificial apoptotic cell, for the arrest of autoimmunity in T1D in a safe manner. [ABSTRACT FROM AUTHOR]

Developing self‐powered nanomotors made of biocompatible and functional components is of paramount importance in future biomedical applications. Herein, the functional features of LipoBots (LBs) composed of a liposomal carrier containing urease enzymes for propulsion, including their protective properties against acidic conditions and their on‐demand triggered activation, are reported. Given the functional nature of liposomes, enzymes can be either encapsulated or coated on the surface of the vesicles. The influence of the location of urease on motion dynamics is first studied, finding that the surface‐urease LBs undergo self‐propulsion whereas the encapsulated‐urease LBs do not. However, adding a percolating agent present in the bile salts to the encapsulated‐urease LBs triggers active motion. Moreover, it is found that when both types of nanomotors are exposed to a medium of similar pH found in the stomach, the surface‐urease LBs lose activity and motion capabilities, while the encapsulated‐urease LBs retain activity and mobility. The results for the protection enzyme activity through encapsulation within liposomes and in situ triggering of the motion of LBs upon exposure to bile salts may open new avenues for the use of liposome‐based nanomotors in drug delivery, for example, in the gastrointestinal tract, where bile salts are naturally present in the intestine. [ABSTRACT FROM AUTHOR]

Herein we report the design, synthesis, structural characterisation and functional testing of a series of Cu(II) coordination polymers containing flexible 4,4′-dithiodibenzoate ligand (4,4′-DTBA), with or without auxiliary N-donor ligands. Reaction of Cu(II) with 4,4′-DTBA yielded a 1D coordination polymer (1) based on Cu(II) paddlewheel units connected by 4,4′-DTBA, to form cyclic loop chains with intramolecular voids that exhibit reversible structural transformations upon subsequent solvent exchange in methanol to afford a new, crystalline, permanently-porous structure (1′). However, when the same reaction was run with pyridine, it formed a porous 2D coordination polymer (2). We have attributed the difference in dimensionality seen in the two products to the coordination of pyridine on the axial site of the Cu(II) paddle-wheel, which forces flexible 4,4′-DTBA to adopt a different conformation. Reactions in the presence of 4,4′-bipyridine (4,4′-bpy) afforded two new, flexible, 2D coordination polymers (3 & 4). Lower concentrations of 4,4′-bpy afforded a structure (3) built from 1D chains analogous to those in 1 and connected through 4,4′-bpy linkers coordinated to the axial positions. Interestingly, 3 showed reversible structural transformations triggered by either solvent exchange or thermal treatment, each of which yielded a new crystalline and permanently porous phase (3′). Finally, use of higher concentrations of 4,4′-bpy led to a coordination polymer (4) based on a distorted CuO3N2 trigonal bipyramid, rather than on the Cu(II) paddlewheel. The connection of these motifs by 4,4′-DTBA resulted in a zig-zag 1D chain connected through 4,4′-bpy ligands to form a porous 2D network. Interestingly, 4 also underwent reversible thermal transformation to yield a microporous coordination polymer (4′). [ABSTRACT FROM AUTHOR]

Miniaturized combined arrays of three different pH indicators allowing for sensitive, robust and broad-range acidity detection are prepared by parallel dip-pen nanolithography, which proves the potential of this technique to fabricate multiplexed platforms at the micro- and nanoscale that can act as sensors. [ABSTRACT FROM AUTHOR]

Dynamic covalent bonds have been advantageously used to direct the synthesis of crystalline porous covalent organic frameworks (COFs). Unlike the standard synthetic protocols that involve harsh conditions, this work provides a high-yield "one-pot" green synthesis of imine-based COFs in water. Additionally, this aqueous synthesis can be performed under microwave conditions, considerably reducing the reaction time. [ABSTRACT FROM AUTHOR]

Ultrathin films of a robust RhII‐based porous metal–organic polyhedra (MOP) have been obtained. Homogeneous and compact monolayer films (ca. 2.5 nm thick) were first formed at the air–water interface, deposited onto different substrates and characterized using spectroscopic methods, scanning transmission electron microscopy and atomic force microscopy. As a proof of concept, the gas separation performance of MOP‐supported membranes has also been evaluated. Selective MOP ultrathin films (thickness ca. 60 nm) exhibit remarkable CO2 permeance and CO2/N2 selectivity, demonstrating the great combined potential of MOP and Langmuir‐based techniques in separation technologies. [ABSTRACT FROM AUTHOR]

The production of metal–organic frameworks (MOFs) in the form of colloids has brought a paradigm shift in the design of new functional porous materials. Along with their intrinsic interest as porous solids, and contrary to their bulk powder counterparts, colloidal MOF particles can additionally be dispersed, shaped, functionalized, transformed and assembled in a controlled manner, conferring them further properties and applications. In this regard, zeolitic imidazolate framework-8 (ZIF-8) has become a pioneering MOF constituent of colloidal science. Today, the understanding of the role of synthetic parameters, learned after one decade of research, enables the production of monodisperse colloidal ZIF-8 particles with tunable dimensions and morphologies, offering the opportunity to develop new functional materials and composites with novel and promising functionalities. This tutorial review provides a useful guide to prepare ZIF-8 in its colloidal form, covering the published studies on the synthesis of homogeneous ZIF-8 particles with controlled size and shape. In addition, we present the most relevant advances in the development of colloidal ZIF-8 hybrid single-particles, reflecting the great potential and rapid development of this interdisciplinary research field. Finally, we highlight how formulation of ZIF-8 as colloids has led to the emergence of novel physicochemical phenomena that are useful for practical applications. This review aims at promoting the development of MOFs as colloids, taking ZIF-8 as a pioneering and successful case that clearly shows the benefits of bridging MOF chemistry and colloidal science. [ABSTRACT FROM AUTHOR]

This article discusses various research articles published in the journal Angewandte Chemie International Edition. One research article by Jorge Albalad, Inhar Imaz, Daniel Maspoch, et al. explores the use of bond scission as a synthetic tool to design new molecules and materials. They demonstrate this concept by obtaining unprecedented Rh(II)-based architectures through the disassembly of metal-organic polyhedra. Another research article by Weijie Yang, Hai-Long Jiang, et al. focuses on incorporating Pd nanoparticles into MOFs for high selectivity in CO esterification. Yoshinari Sawama, et al. report on sulfonium salt reagents for introducing deuterated alkyl groups in drug discovery, while Alexis Bordet, Walter Leitner, et al. discuss the adaptivity of a catalyst in the hydrogenation of heteroaromatics. Lastly, Leticia González, et al. investigate the photophysics of [Ru(bpy)3]2+ and propose a kinetic model for its behavior. [Extracted from the article]