Defluorinative Coupling of (NH)-Heteroarenes and Unactivated Vinyl Fluorides Enabled by Metal-Organic Frameworks.

-vinyl azoles are prevalent moieties in pharmaceuticals, and fluorovinyl groups are widely recognized as carbonyl bioisosteres in drug design. Thus, -fluorovinylated heteroarenes represent highly desirable functional groups in medicinal chemistry. To streamline the development of novel -fluorovinylation and -pentafluoropropenylation reactions, herein we safely handle fluorinated gases, such as vinylidene fluoride (VDF) and hexafluoropropene (HFP), as solid reagents using a metal-organic framework (MOF), Mg(dobdc) (dobdc = 2,5-dioxidobenzene-1,4-dicarboxylate).

Polymer connectivity governs electrophotocatalytic activity in the solid state.

The reductive functionalization of inert substrates such as chloroarenes is a critical yet challenging transformation relevant to both environmental remediation and organic synthesis. Combining electricity and light is an emerging strategy to access the deeply reducing potentials required for single electron transfer to chloroarenes, yet this approach is limited by poor stability and mechanistic ambiguity. Here we demonstrate heterogeneous electrophotocatalysis using redox-active rylene diimide polymers for the reduction of chloroarenes.

Effects of a Single Atom Substitution on the Physical Properties, Excited State Dynamics, and Iodine Capture Performance of Emissive Covalent Organic Frameworks.

A common strategy for developing emissive covalent organic frameworks (COFs) with varied properties is incorporating diverse chromophoric monomers. Herein, an alternative approach is adopted to demonstrate that a simple alteration in just one atom (oxygen vs. sulfur) in monomer design can result in significant differences in the physical, chemical, and photophysical properties of the resulting COFs.

A coarse-grained simulation toolkit for metal-organic framework synthesis.

To gain a better understanding of the processes with which metal-organic frameworks (MOFs) self-assemble, we construct a coarse-grained simulation toolkit to model the growth of a wide variety of MOF structure types. We employ the topology and symmetry of the underlying net of the framework structure to design building blocks that correspond to MOF components. Sphere-union polyhedra are constructed to model MOF nodes by choosing the types and positions of simulation beads, as well as the specific interactions between them, to correspond to the node coordination and local symmetry.

Carbon Capture from Natural Gas Flue Emissions and Air via (Bi)Carbonate Formation in a Cyclodextrin-Based Metal-Organic Framework.

Carbon capture and utilization or sequestration (CCUS) from industrial point sources and direct air capture (DAC) are both necessary to curb the rising atmospheric levels of CO. Amine scrubbers, the current leading carbon capture technology, suffer from poor oxidative and thermal stability, limiting their long-term cycling stability under oxygen-rich streams such as air and the emissions from natural gas combined cycle (NGCC) power plants. Herein, we demonstrate that the hydroxide-based cyclodextrin metal-organic framework (CD-MOF) RbCO CD-MOF ST possesses high CO capacities from dry dilute streams at low temperatures and humid streams at elevated temperatures.

Enhancing Selective Hydrofluorocarbon Greenhouse Gas Capture via Halogenation of Metal-Organic Frameworks.

Hydrofluorocarbons (HFCs) are anthropogenically produced greenhouse gases with longer atmospheric lifetimes and higher global warming potentials than those of carbon dioxide. General strategies to abate their emissions from industrial point sources, such as via adsorptive capture, remain scarce. Herein, we uncover the key structure-property relationships that lead to strong binding of HFCs such as fluoroform (CHF) and difluoromethane (CHF) in metal-organic frameworks (MOFs) under the low pressures relevant to flue gas scrubbing.

Harnessing Oxidized Amines as Robust Sorbents for Carbon Capture.

Carbon capture and sequestration (CCS) is imperative to mitigating global climate change, but current implementation falls far short of that needed to reach net-zero global emissions by 2050. Aqueous amine solutions, conceived over a century ago, are the current leading technology for CO separations. However, amines suffer from chemical instability under scrubbing conditions, corrosiveness, and toxicity, hindering their long-term implementation at multiton scales.

Toward Pore Size-Selective Photoredox Catalysis Using Bifunctional Microporous 2D Triazine-Based Covalent Organic Frameworks.

The design and synthesis of photoactive metal-free 2D materials for selective heterogeneous photoredox catalysis continue to be challenging due to issues related to nonrecyclability, and limited photo- and chemical stability. Herein, we report the photocatalytic properties of a triazine-based porous COF, , which is found to be capable of facilitating both SET (single electron transfer) for photocatalytic reductive debromination of phenacyl bromide in absence of oxygen and generation of reactive oxygen species (ROS) for benzylamine photo-oxidation in the presence of oxygen, respectively, under visible light irradiation. Inspired by the latter results, we further systematically investigated different-sized benzylamine substrates in this single-component reaction and compared the results with an analogous COF () exhibiting a larger pore size.

Polymer Connectivity Governs Electrophotocatalytic Activity in the Solid State.

The reductive functionalization of inert substrates like chloroarenes is a critical yet challenging transformation relevant to both environmental remediation and organic synthesis. Combining electricity and light is an emerging approach to access the deeply reducing potentials required for single electron transfer to chloroarenes, yet this approach is held back by the poor stability and mechanistic ambiguity of current homogeneous systems. Incorporating redox-active moieties into insoluble organic materials represents a promising strategy to unlock new heterogeneous catalytic activity while improving catalyst stability.

Defect-Engineered Metal-Organic Frameworks as Bioinspired Heterogeneous Catalysts for Amide Bond Formation.

The synthesis of amides from amines and carboxylic acids is the most widely carried out reaction in medicinal chemistry. Yet, most amide couplings are still conducted using stoichiometric reagents, leading to significant waste; few synthetic catalysts for this transformation have been adopted industrially due to their limited scope and/or poor recyclability. The majority of catalytic approaches focus on a single activation mode, such as enhancing the electrophilicity of the carboxylic acid partner using a Lewis acid.

A Strongly Reducing sp Carbon-Conjugated Covalent Organic Framework Formed by N-Heterocyclic Carbene Dimerization.

Covalent organic frameworks linked by carbon-carbon double bonds (C=C COFs) are an emerging class of crystalline, porous, and conjugated polymeric materials with potential applications in organic electronics, photocatalysis, and energy storage. Despite the rapidly growing interest in sp carbon-conjugated COFs, only a small number of closely related condensation reactions have been successfully employed for their synthesis to date. Herein, we report the first example of a C=C COF, CORN-COF-1 (CORN=Cornell University), prepared by N-heterocyclic carbene (NHC) dimerization.

Transdermal Hydrogen Sulfide Delivery Enabled by Open-Metal-Site Metal-Organic Frameworks.

Hydrogen sulfide (HS) is an endogenously produced gasotransmitter involved in many physiological processes that are integral to proper cellular functioning. Due to its profound anti-inflammatory and antioxidant properties, HS plays important roles in preventing inflammatory skin disorders and improving wound healing. Transdermal HS delivery is a therapeutically viable option for the management of such disorders.

Gas Delivery Relevant to Human Health using Porous Materials.

Gases are essential for various applications relevant to human health, including in medicine, biomedical imaging, and pharmaceutical synthesis. However, gases are significantly more challenging to safely handle than liquids and solids. Herein, we review the use of porous materials, such as metal-organic frameworks (MOFs), zeolites, and silicas, to adsorb medicinally relevant gases and facilitate their handling as solids.

Paired Electrolysis Enables Reductive Heck Coupling of Unactivated (Hetero)Aryl Halides and Alkenes.

The formation of carbon-carbon (C-C) bonds is a cornerstone of organic synthesis. Among various methods to construct Csp-Csp bonds, the reductive Heck reaction between (hetero)aryl halides and alkenes stands out due to its potential efficiency and broad substrate availability. However, traditional reductive Heck reactions are limited by the use of precious metal catalysts and/or limited aryl halide and alkene compatibility.

Capturing carbon dioxide from air with charged-sorbents.

Emissions reduction and greenhouse gas removal from the atmosphere are both necessary to achieve net-zero emissions and limit climate change. There is thus a need for improved sorbents for the capture of carbon dioxide from the atmosphere, a process known as direct air capture. In particular, low-cost materials that can be regenerated at low temperatures would overcome the limitations of current technologies.

Redox-Active Organic Materials: From Energy Storage to Redox Catalysis.

Electroactive materials are central to myriad applications, including energy storage, sensing, and catalysis. Compared to traditional inorganic electrode materials, redox-active organic materials such as porous organic polymers (POPs) and covalent organic frameworks (COFs) are emerging as promising alternatives due to their structural tunability, flexibility, sustainability, and compatibility with a range of electrolytes. Herein, we discuss the challenges and opportunities available for the use of redox-active organic materials in organoelectrochemistry, an emerging area in fine chemical synthesis.

Selective adsorption of fluorinated super greenhouse gases within a metal-organic framework with dynamic corrugated ultramicropores.

Perfluorocompound (PFC) gases play vital roles in microelectronics processing. Requirements for ultra-high purities traditionally necessitate use of virgin sources and thereby hinder the capture, purification, and reuse of these costly gases. Most importantly, gaseous PFCs are incredibly potent greenhouse gases with atmospheric lifetimes on the order of 10-10 years, and thus any environmental emissions have an outsized and prolonged impact on our climate.

Cobalt(III) Halide Metal-Organic Frameworks Drive Catalytic Halogen Exchange.

The selective halogenation of complex (hetero)aromatic systems is a critical yet challenging transformation that is relevant to medicinal chemistry, agriculture, and biomedical imaging. However, current methods are limited by toxic reagents, expensive homogeneous second- and third-row transition metal catalysts, or poor substrate tolerance. Herein, we demonstrate that porous metal-organic frameworks (MOFs) containing terminal Co(III) halide sites represent a rare and general class of heterogeneous catalysts for the controlled installation of chlorine and fluorine centers into electron-deficient (hetero)aryl bromides using simple metal halide salts.

Simplifying the Synthesis of Metal-Organic Frameworks.

Metal-organic frameworks (MOFs) are porous, crystalline materials constructed from organic linkers and inorganic nodes that have attracted widespread interest due to their permanent porosity and highly modular structures. However, the large volumes of organic solvents and additives, long reaction times, and specialized equipment typically required to synthesize MOFs hinder their widespread adoption in both academia and industry. Recently, our lab has developed several user-friendly methods for the gram-scale (1-100 g) preparation of MOFs.

MOFganic Chemistry: Challenges and Opportunities for Metal-Organic Frameworks in Synthetic Organic Chemistry.

Metal-organic frameworks (MOFs) are porous, crystalline solids constructed from organic linkers and inorganic nodes that have been widely studied for applications in gas storage, chemical separations, and drug delivery. Owing to their highly modular structures and tunable pore environments, we propose that MOFs have significant untapped potential as catalysts and reagents relevant to the synthesis of next-generation therapeutics. Herein, we outline the properties of MOFs that make them promising for applications in synthetic organic chemistry, including new reactivity and selectivity, enhanced robustness, and user-friendly preparation.

Handling fluorinated gases as solid reagents using metal-organic frameworks.

Fluorine is an increasingly common substituent in pharmaceuticals and agrochemicals because it improves the bioavailability and metabolic stability of organic molecules. Fluorinated gases represent intuitive building blocks for the late-stage installation of fluorinated groups, but they are generally overlooked because they require the use of specialized equipment. We report a general strategy for handling fluorinated gases as benchtop-stable solid reagents using metal-organic frameworks (MOFs).

Flexible Backbone Effects on the Redox Properties of Perylenediimide-Based Polymers.

Organic electrode materials are appealing candidates for a wide range of applications, including heterogeneous electrocatalysis and electrochemical energy storage. However, a narrow understanding of the structure-property relationships in these materials hinders the full realization of their potential. Herein, we investigate a family of insoluble perylenediimide (PDI) polymers to interrogate how backbone flexibility affects their thermodynamic and kinetic redox properties.