Functional Porous Materials: Applications for Environmental Sustainability

Resource depletion, clean water shortages, and global climate change have led to environmental sustainability being of primary concern for both governmental and industrial practices. Current methods to address these challenges typically come as a double-edged sword, fixing one problem while contributing to another. As introduced in chapter one of this dissertation, adsorbent materials are seen as a promising alternative remediation system due to their low energy consumption and minimal chemical waste production. However, many traditional adsorbents, such as activated carbon, metal oxides, and resins, are hindered in practice. This is because they lack the structural tunability to have long-term effectiveness and/or specificity in application. Advanced materials can move beyond traditional adsorbents and are recognized for the vast number of molecular arrangements available to form extended porous structures. Materials in this realm include metal-organic frameworks (MOFs) and porous organic polymers (POPs), which have been successful in a variety of applications, with the focus of this work on resource recovery, water treatment, and air purification. Chapters two and three explore structural modifications to enhance POPs for the recovery of finite natural resources. Palladium and uranium were the analytes of choice due to their wide use in the industrial and energy sector, respectively. POPs were found to have high stability in aqueous solutions, rapid kinetic efficiency, and selective recovery of the targets even in solutions with diverse chemical compositions; all important metrics for moving these adsorbents into practice. It was experimentally determined that performance could be greatly enhanced through variations of the binding site, highlighting the potential of such advanced materials. Chapters four and five detail work done to employ MOFs and POPs for water treatment applications with a focus on nuclear and industrial waste streams. The organic struts of a water-stable MOF, MIL-101, were functionalized with a high density of ionexchange sites for effective capture of the radionuclides, cesium and strontium. Isolation of such compounds is required to reduce the total volume of nuclear waste that must be stored permanently. More prevalent, however, are the numerous industrial processes that contribute to a large influx of toxic compounds in waste streams, which can seep into our water sources. Of these, mercury is a toxin of concern with environmental and human health implications. A stable POP functionalized with a thiol group (POP-SH) was found to have a high mercury uptake capacity with fast kinetics due to the strong interaction of multiple functional groups in close proximity. These results indicate the exceptional performance that can be achieved through a targeted approach to remove contaminants from water. Chapters five and six concentrate on air purification via capture of volatile contaminants, as well as the utilization of gases as a reactant for organic transformations. Due to the stability of the POP platform, POP-SH was able to remove mercury in the vapor phase, thus demonstrating its applicability in multiple stages of the mercury cycle. Furthermore, of overwhelming concern is the excess carbon dioxide in the environment, contributing to global climate change. Rather than traditional carbon capture and storage methods, using carbon dioxide for organic reactions can not only reduce the concentration in air, but also upcycle it to produce industrially relevant compounds such as cyclic carbonates. Through the use of a MOF as a functional host, the cycloaddition of epoxides with carbon dioxide can be achieved with minimal energy input. This technique fully utilizes the structural components of a MOF with promising results. This work demonstrates the success of advanced adsorbent materials for a multitude of applications aimed at environmental sustainability, and how structural and chemical modifications contribute to their effectiveness. Through optimization of the material’s design for the proposed function, enhancements in performance can move such materials into large-scale applications. This strategy can not only ensure the prolonged health of our environment, but also be applied for further technological development of advanced materials

Mercury capture using functionalized porous organic polymer with hierarchical porosity

Compositions are provided for binding mercury based in porous organic polymers having (i) a plurality of repeat units having heavy metal chelator moieties covalently attached thereto and (ii) a plurality of pores having a hierarchical pore size distribution over a range of pore sizes. In some aspects, the range of pore sizes is about 5 nm to 10 nm. The compositions can have a maximum mercury uptake capacity of 1,000 mg gâ1 to 2,000 mg gâ1 at 1 atm and 296 K and has a mercury uptake capacity that is stable and recyclable. Methods of making the compositions and methods of using the compositions for uptake of mercury are also provided

Metalloenzyme Mimicry at the Nodes of Metal-Organic Frameworks

In this issue of Chem, Dincă and co-workers show that the node of the metal-organic framework MFU-4l can be modified by anion exchange to serve as a biomimetic model of carbonic anhydrase given the similarity in their ligand fields. The resulting material, which has reactivity characteristics of the enzyme, gives great promise for CO2-related applications

Multifunctional porous materials for water purification and remediation

A variety of compositions and materials are provided for water purification and remediation. The compositions including multiple functionalities for treating a variety of pollutants or contaminants. The compositions can include a porous organic polymer with one or more of a variety of functional groups for binding the contaminants and with a hierarchical pore size distribution over a range of pore sizes to facilitate enhanced removal of the contaminants. Functional groups can include one, two, or more different functional groups such as amines, halides, ammoniums, pyridiuiums, thiols, imidazoliums, salts thereof, or others. The range of pore sizes can be about 1 nm to 10 nm or more. Contaminants can include antimony, arsenic, barium, beryllium, cadmium, chromium, copper, lead, mercury, selenium, technetium, thallium, uranium, radium, urea, and phosphate. Methods of removing the contaminants from water using the compositions are also provided

Multifunctional porous materials for water purification and remediation

A variety of compositions and materials are provided for water purification and remediation. The compositions including multiple functionalities for treating a variety of pollutants or contaminants. The compositions can include a porous organic polymer with one or more of a variety of functional groups for binding the contaminants and with a hierarchical pore size distribution over a range of pore sizes to facilitate enhanced removal of the contaminants. Functional groups can include one, two, or more different functional groups such as amines, halides, ammoniums, pyridiuiums, thiols, imidazoliums, salts thereof, or others. The range of pore sizes can be about 1 nm to 10 nm or more. Contaminants can include antimony, arsenic, barium, beryllium, cadmium, chromium, copper, lead, mercury, selenium, technetium, thallium, uranium, radium, urea, and phosphate. Methods of removing the contaminants from water using the compositions are also provided

Covalent Organic Frameworks: Opportunities of Covalent Organic Frameworks for Advanced Applications

Covalent organic frameworks (COFs) are an emerging class of functional nanostructures with intriguing properties, due to their unprecedented combination of high crystallinity, tunable pore size, large surface area, and unique molecular architecture. The enormous possible design space available within COFs provides virtually unlimited room for imagination, allowing designed incorporation of different functionalities. In article number 1801410, Qi Sun, Shengqian Ma, and co-workers review the recent advancements of COFs for numerous applications

Opportunities of Covalent Organic Frameworks for Advanced Applications

Covalent organic frameworks (COFs) are an emerging class of functional nanostructures with intriguing properties, due to their unprecedented combination of high crystallinity, tunable pore size, large surface area, and unique molecular architecture. The range of properties characterized in COFs has rapidly expanded to include those of interest for numerous applications ranging from energy to environment. Here, a background overview is provided, consisting of a brief introduction of porous materials and the design feature of COFs. Then, recent advancements of COFs as a designer platform for a plethora of applications are emphasized together with discussions about the strategies and principles involved. Finally, challenges remaining for this type material for real applications are outlined

Opportunities of Covalent Organic Frameworks for Advanced Applications

Covalent organic frameworks (COFs) are an emerging class of functional nanostructures with intriguing properties, due to their unprecedented combination of high crystallinity, tunable pore size, large surface area, and unique molecular architecture. The range of properties characterized in COFs has rapidly expanded to include those of interest for numerous applications ranging from energy to environment. Here, a background overview is provided, consisting of a brief introduction of porous materials and the design feature of COFs. Then, recent advancements of COFs as a designer platform for a plethora of applications are emphasized together with discussions about the strategies and principles involved. Finally, challenges remaining for this type material for real applications are outlined

Covalent Organic Frameworks: Opportunities of Covalent Organic Frameworks for Advanced Applications

Covalent organic frameworks (COFs) are an emerging class of functional nanostructures with intriguing properties, due to their unprecedented combination of high crystallinity, tunable pore size, large surface area, and unique molecular architecture. The enormous possible design space available within COFs provides virtually unlimited room for imagination, allowing designed incorporation of different functionalities. In article number 1801410, Qi Sun, Shengqian Ma, and co-workers review the recent advancements of COFs for numerous applications

Creating Solvation Environments in Heterogeneous Catalysts for Efficient Biomass Conversion

Chemical transformations are highly sensitive toward changes in the solvation environment and solvents have long been used to control their outcome. Reactions display unique performance in solvents like ionic liquids or DMSO, however, isolating products from them is cumbersome and energy-consuming. Here, we develop promising alternatives by constructing solvent moieties into porous materials, which in turn serve as platforms for introducing catalytic species. Due to the high density of the solvent moieties, these porous solid solvents (PSSs) retain solvation ability, which greatly influences the performance of incorporated active sites via concerted non-covalent substrate–catalyst interactions. As a proof-of-concept, the -SO3H-incorporated PSSs exhibit high yields of fructose to 5-hydroxymethylfurfural in THF, which exceeds the best results reported using readily separable solvents and even rivals those in ionic liquids or DMSO. Given the wide application, our strategy provides a step forward towards sustainable synthesis by eliminating the concerns with separation unfriendly solvents