<i>N</i>‑Dimethylation and <i>N</i>‑Functionalization of Amines Using Ru Nanoparticle Catalysts and Formaldehyde or Functional Aldehydes as the Carbon Source

N-methylated amines are essential bioactive compounds and have been widely used in the fine and bulk chemical industries, as well as in pharmaceuticals, agrochemicals, and dyes. Developing green, efficient, and low-cost catalysts for methylation of amines by using efficient and easily accessible methylating reagents is highly desired yet remains a significant challenge. Herein, we report the selective N-dimethylation of different functional amines with different functional aldehydes under easy-to-handle and industrially applicable conditions using carbon-supported Ru nanoparticles (Ru/C) as a heterogeneous catalyst. A broad spectrum of amines could be efficiently converted to their corresponding N,N-dimethyl amines with good compatibility of various functional groups. This method is widely applicable to N-dimethylation of primary amines including aromatic, aliphatic amines with formaldehyde, and synthesis of tertiary amines from primary, secondary amines with different functional aldehydes. The advantage of this newly described method includes operational simplicity, high turnover number, the ready availability of the catalyst, and good functional group compatibility. This Ru/C catalyzed N-dimethylation reaction possibly proceeds through a two-step N-methylation reaction process

Tailored Porous Organic Polymers for Task-Specific Water Purification

ConspectusThe Industrial Revolution has resulted in social and economic improvements, but unfortunately, with the development of manufacturing and mining, water sources have been pervaded with contaminants, putting Earth’s freshwater supply in peril. Therefore, the segregation of pollutantssuch as radionuclides, heavy metals, and oil spillsfrom water streams, has become a pertinent problem. Attempts have been made to extract these pollutants through chemical precipitation, sorbents, and membranes. The limitations of the current remediation methods, including the generation of a considerable volume of chemical sludge as well as low uptake capacity and/or selectivity, actuate the need for materials innovation. These insufficiencies have provoked our interest in the exploration of porous organic polymers (POPs) for water treatment. This category of porous material has been at the forefront of materials research due to its modular nature, i.e., its tunable functionality and tailorable porosity. Compared to other materials, the practicality of POPs comes from their purely organic composition, which lends to their stability and ease of synthesis. The potential of using POPs as a design platform for solid extractors is closely associated with the ease with which their pore space can be functionalized with high densities of strong adsorption sites, resulting in a material that retains its robustness while providing specified interactions depending on the contaminant of choice.POPs raise opportunities to improve current or enable new technologies to achieve safer water. In this Account, we describe some of our efforts toward the exploitation of the unique properties of POPs for improving water purification by answering key questions and proposing research opportunities. The design strategies and principles involved for functionalizing POPs include the following: increasing the density and flexibility of the chelator to enhance their cooperation, introducing the secondary sphere modifiers to reinforce the primary binding, and enforcing the orientation of the ligands in the pore channel to increase the accessibility and cooperation of the functionalities. For each strategy, we first describe its chemical basis, followed by presenting examples that convey the underlying concepts, giving rise to functional materials that are beyond the traditional ones, as demonstrated by radionuclide sequestration, heavy metal decontamination, and oil-spill cleanup. Our endeavors to explore the applicability of POPs to deal with these high-priority contaminants are expected to impact personal consumer water purifiers, industrial wastewater management systems, and nuclear waste management. In our view, more exciting will be new applications and new examples of the functionalization strategies made by creatively merging the strategies mentioned above, enabling increasingly selective binding and efficiency and ultimately promoting POPs for practical applications to enhance water security

Nanospace Decoration with Uranyl-Specific “Hooks” for Selective Uranium Extraction from Seawater with Ultrahigh Enrichment Index

Mining uranium from seawater is highly desirable for sustaining the increasing demand for nuclear fuel; however, access to this unparalleled reserve has been limited by competitive adsorption of a wide variety of concentrated competitors, especially vanadium. Herein, we report the creation of a series of uranyl-specific “hooks” and the decoration of them into the nanospace of porous organic polymers to afford uranium nanotraps for seawater uranium extraction. Manipulating the relative distances and angles of amidoxime moieties in the ligands enabled the creation of uranyl-specific “hooks” that feature ultrahigh affinity and selective sequestration of uranium with a distribution coefficient threefold higher compared to that of vanadium, overcoming the long-term challenge of the competing adsorption of vanadium for uranium extraction from seawater. The optimized uranium nanotrap (2.5 mg) can extract more than one-third of the uranium in seawater (5 gallons), affording an enrichment index of 3836 and thus presenting a new benchmark for uranium adsorbent. Moreover, with improved selectivity, the uranium nanotraps could be regenerated using a mild base treatment. The synergistic combination of experimental and theoretical analyses in this study provides a mechanistic approach for optimizing the selectivity of chelators toward analytes of interest

Nanospace Decoration with Uranyl-Specific “Hooks” for Selective Uranium Extraction from Seawater with Ultrahigh Enrichment Index

Mining uranium from seawater is highly desirable for sustaining the increasing demand for nuclear fuel; however, access to this unparalleled reserve has been limited by competitive adsorption of a wide variety of concentrated competitors, especially vanadium. Herein, we report the creation of a series of uranyl-specific “hooks” and the decoration of them into the nanospace of porous organic polymers to afford uranium nanotraps for seawater uranium extraction. Manipulating the relative distances and angles of amidoxime moieties in the ligands enabled the creation of uranyl-specific “hooks” that feature ultrahigh affinity and selective sequestration of uranium with a distribution coefficient threefold higher compared to that of vanadium, overcoming the long-term challenge of the competing adsorption of vanadium for uranium extraction from seawater. The optimized uranium nanotrap (2.5 mg) can extract more than one-third of the uranium in seawater (5 gallons), affording an enrichment index of 3836 and thus presenting a new benchmark for uranium adsorbent. Moreover, with improved selectivity, the uranium nanotraps could be regenerated using a mild base treatment. The synergistic combination of experimental and theoretical analyses in this study provides a mechanistic approach for optimizing the selectivity of chelators toward analytes of interest