NMR-Enhanced Crystallography Aids Open Metal–Organic Framework Discovery Using Solvent-Free Accelerated Aging

We demonstrate the combined use of NMR-enhanced crystallography and solvent-free synthesis by accelerated aging (AA), for the discovery and structural characterization of a novel cadmium-based open metal–organic framework (MOF) belonging to the class of zeolitic imidazolate frameworks (ZIFs). Although solid-state NMR spectroscopy has been used to assist in structural characterization of crystalline solids by powder X-ray diffraction (PXRD), typically through quantification of the contents of the asymmetric unit, this work highlights how it can take a more active role in guiding structure determination, by elucidating the coordination environment of the metal node in a novel MOFs. Exploration of AA reactions of cadmium oxide (CdO) and 2-methylimidazole (HMeIm) enabled the synthesis of not only the previously reported yqt1-topology framework but also a new material (1) exhibiting a Cd/MeIm ratio of 1:3, contrasting the 1:2 ratio expected for a ZIF. Structural characterization of 1 was enabled by using 111Cd solid-state nuclear magnetic resonance (SSNMR) to provide information on the coordination environment of the cadmium node. Specifically, 111Cd SSNMR experiments were conducted on a series of model compounds to correlate the cadmium coordination environment to the observed isotropic chemical shift, δiso(111Cd), followed by multinuclear SSNMR experiments on 1 to determine the nature of the metal coordination environment and the number of distinct chemical sites. This information was used in refinement of the molecular level structure from the available PXRD data, a technique termed NMR-enhanced crystallography, revealing that 1 is an open diamondoid (dia) topology Cd(MeIm)2 framework based on Cd2+ ions tetrahedrally coordinated with MeIm– ligands and additional HMeIm guest molecules within the framework pores. Although AA was initially devised as a clean, mild route for making MOFs, these results provide a proof-of-principle of how, by combining it with SSNMR spectroscopy as a means to overcome limitations of PXRD structure determination, it can be used to screen for new solid phases in the absence of solvents, high temperatures, or mechanical impact that are inherent to other thermally-, solution-, or mechanochemically-based techniques

Advances in Solid-State Transformations of Coordination Bonds: From the Ball Mill to the Aging Chamber

Controlling the formation of coordination bonds is pivotal to the development of a plethora of functional metal-organic materials, ranging from coordination polymers, metal-organic frameworks (MOFs) to metallodrugs. The interest in and commercialization of such materials has created a need for more efficient, environmentally-friendly routes for making coordination bonds. Solid-state coordination chemistry is a versatile greener alternative to conventional synthesis, offering quantitative yields, enhanced stoichiometric and topological selectivity, access to a wider range of precursors, as well as to molecules and materials not readily accessible in solution or solvothermally. With a focus on mechanochemical, thermochemical and “accelerated aging” approaches to coordination polymers, including pharmaceutically-relevant materials and microporous MOFs, this review highlights the recent advances in solid-state coordination chemistry and techniques for understanding the underlying reaction mechanisms

Advances in Solid-State Transformations of Coordination Bonds: From the Ball Mill to the Aging Chamber

Controlling the formation of coordination bonds is pivotal to the development of a plethora of functional metal-organic materials, ranging from coordination polymers, metal-organic frameworks (MOFs) to metallodrugs. The interest in and commercialization of such materials has created a need for more efficient, environmentally-friendly routes for making coordination bonds. Solid-state coordination chemistry is a versatile greener alternative to conventional synthesis, offering quantitative yields, enhanced stoichiometric and topological selectivity, access to a wider range of precursors, as well as to molecules and materials not readily accessible in solution or solvothermally. With a focus on mechanochemical, thermochemical and “accelerated aging” approaches to coordination polymers, including pharmaceutically-relevant materials and microporous MOFs, this review highlights the recent advances in solid-state coordination chemistry and techniques for understanding the underlying reaction mechanisms

NMR-Enhanced Crystallography Aids Open Metal-Organic Framework Discovery Using Solvent-Free Accelerated Aging

NMR-enhanced crystallography enables the characterization of a novel cadmium-based, open metal-organic framework (MOF) from a solvent-free "accelerated aging" process. Whereas accelerated aging was devised as a clean, mild route for making MOFs, these results highlight how it application in materials discovery and characterization is aided by a combination of X-ray diffraction and solid-state NMR spectroscopy.<br /

Highly Photostable and Fluorescent Microporous Solids Prepared via Solid-State Entrapment of Boron Dipyrromethene Dyes in a Nascent Metal–Organic Framework

We report a strategy to synthesize highly emissive, photostable, microporous materials by solid-state entrapment of boron dipyrromethene (BODIPY) fluorophores in a metal–organic framework. Solvent-free mechanochemistry or accelerated aging enabled quantitative capture and dispersal of the PM605 dye within the ZIF-8 framework starting from inexpensive, commercial materials. While the design of emissive BODIPY solids is normally challenged by quenching in a densely packed environment, herein reported PM605@ZIF-8 materials show excellent emissive properties and to the best of our knowledge an unprecedented ∼10-fold enhancement of BODIPY photostability. Time-resolved and steady-state fluorescence studies of PM605@ZIF-8 show that interchromophore interactions are minimal at low dye loadings, but at higher ones lead to through-pore energy transfer between chromophores and to aggregate species.Fil: Glembockyte, Viktorija. McGill University; CanadáFil: Frenette, Mathieu. Mcgill University; Canadá. Université du Québec a Montreal; CanadáFil: Mottillo, Cristina. Mcgill University; CanadáFil: Durantini, Andres Matías. Mcgill University; Canadá. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Química; Argentina. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; ArgentinaFil: Gostick, Jeff. Mcgill University; CanadáFil: Strukil, Vjekoslav. Mcgill University; Canadá. Ruđer Bošković Institute; CroaciaFil: Friščić, Tomislav. Mcgill University; Canadá. Ruđer Bošković Institute; CroaciaFil: Cosa, Gonzalo. Mcgill University; Canad

Metal-organic frameworks induce hypergolic ignition of bulk metals

We demonstrate the unprecedented ability to induce hypergolic behavior, i.e. rapid and spontaneous ignition upon contact with an oxidizer, in non-hypergolic metal fuels by blending them with hypergolic metal-organic frameworks (HMOFs). Using magnesium, aluminum or zinc metal as the fuel, we demonstrate materials with ignition delays (IDs) below 50 ms, and calculated specific impulse (Isp) in the 220-250 s range. These parameters are comparable to those of toxic and carcinogenic hydrazine-based hypergols conventionally used in aerospace technologies, suggesting a route to develop cleaner, safer propulsion systems