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Climate Action can “Flip the Switch”: Resourcing Climate Empowerment in Chemistry Education
No full textTraditional approaches to chemistry curriculum for undergraduate students prioritize coverage of fragmented individual topics rather than employing systems thinking to embed chemistry concepts in immersive holistic contexts vital to our planet’s future, such as climate change. Many students are eager to understand and tackle climate change, drawing on political, socio-economic, sustainability and chemistry perspectives. However, educators face substantial barriers in resourcing climate empowerment through chemistry education. This paper outlines interactive resources and activities educators can use to help students engage with climate literacy and action, grounded in an emerging understanding of key concepts in chemistry. These resources draw from the work of 14 third- and fourth-year undergraduate students at The King’s University who were learning about climate change in an environmental chemistry class. The students collaborated in small groups and as an entire class to develop learning activities, pilot activities created by others, articulate topics for educators, and perform several rounds of peer review. Topics chosen for this publication include systems thinking and Earth systems connections; the nature of and evidence for climate change; Earth’s radiation balance, greenhouse gases, and climate engineering; models to forecast the future; and chemistry’s role in solutions. Together, the students developed activities and learning outcomes they hope others will use to connect climate change to cognitive, affective, and kinesthetic learning in chemistry
Data augmentation in a triple transformer loop retrosynthesis model
No full textThe reaction dataset from the US Patent Office (USPTO), which is used broadly for training computer-assisted synthesis planning (CASP) retrosynthesis models, is biased towards a few over-represented reaction types such as palladium couplings and protecting group operations. Here we applied 14,325 reaction templates extracted from USPTO reactions to 1,505,837 USPTO molecules and used a transformer-based approach derived from our recently reported triple transformer loop (TTL) retrosynthesis model to test and validate up to 5,000 reactions per template. This approach yielded 25.7 million fictive reactions, from which we selected up to 90 reactions per template to form an equilibrated augmented dataset of 1,000,245 reactions. Combining the original USPTO dataset with this augmented dataset by multitask transfer learning produced a new TTL model with increased performance in terms of overall and template averaged single step round-trip accuracy. Further performance increases were obtained by applying a new disconnection-aware forward validation transformer
Gold-Catalyzed Migratory Insertion of Alkynes
No full textHerein, for the first time, we disclose the migratory insertion of alkynes into Au(III)‒C bonds in a catalytic fashion. Experimental results clearly suggest that the migratory insertion pathway predominates over the π-activation pathway - a finding further supported by the Density Functional Theory (DFT) calculations. The observed regioselectivity underscores the distinct advantages and complementarity of gold catalysis in comparison to palladium catalysis
Installation of Superacidic Carbon Acid Moieties into Polymer Materials via PostPolymerization Modification
No full textIn the fields of polymer and material chemistries, strong acid units have mainly included sulfonic acids, which has limited the extension of related material chemistries. Here, a unique carbon acid functionality, namely the bis[(trifluoromethyl)sulfonyl]methyl group, was integrated with polymers via a simple postpolymerization modification with the outstandingly electrophilic 1,1-bis[(trifluoromethyl)sulfonyl]ethylene. The proposed synthesis protocol was verified as an efficient process even for solid-state reactions. The synthesis afforded an organic material with a surface decorated with bis[(trifluoromethyl)sulfonyl]methyl units. The fabricated membranes featuring surface bis[(trifluoromethyl)sulfonyl]methyl units functioned as efficient organocatalysts with high catalytic activity for the Mukaiyama aldol reaction. This study provides a simple method for installing superacidic carbon acid moieties onto the surfaces of materials without tedious chemical treatments
Regioselective Intermolecular Carboamination of Allylamines via Nucleopalladation for Efficient Vicinal Diamine Synthesis
No full textAn intermolecular carboamination reaction of allyl amines under Pd(II)-catalysis is reported, expediting the synthesis of valuable vicinal diamines embedded in a functionally enriched linear carbon framework with high yields and exclusive Markovnikov selectivity. Central to our approach is the strategic use of a removable picolinamide auxiliary, which directs the regioselectivity during aminopalladation and stabilizes the crucial 5,5-palladacycle intermediate. This stabilization facilitates oxidative addition to carbon electrophiles, enabling the simultaneous incorporation of diverse aryl/styryl groups as well as important amine motifs, such as sulfoximines and anilines, across carbon-carbon double bonds. The protocol features broad substrate compatibility, tolerance to various functional groups, and scalability. The utility of this method is further demonstrated by the site-selective diversification of pharmaceutical agents. Additionally, these products serve as versatile intermediates for synthesizing heterocycles and function as effective ligands in catalytic transfer hydrogenation reactions. Notably, this work represents a rare instance of nucleopalladation-guided intermolecular carboamination of allylamines
Cation⋅⋅⋅anion and anion⋅⋅⋅anion interactions compete in hydrogen-bonded frameworks prepared using amidinium⋅⋅⋅phosphonate hydrogen bonding
No full textWe report the synthesis of hydrogen-bonded frameworks prepared from guanidinium, bis-amidinium or tetra-amidinium cations, and diphosphonate or tetraphosphonate anions. The frameworks are assembled by both charge-assisted amidinium⋅⋅⋅phosphonate and anti-electrostatic phosphonate⋅⋅⋅phosphonate hydrogen bonds, of which the phosphonate⋅⋅⋅phosphonate interactions are notably shorter. Frameworks prepared from the tetrahedral tetraphosphonate building block contain relatively large water-filled channels, but lose crystallinity upon drying. The crystal structure of a guanidinium⋅⋅⋅diphosphonate salt has an unusual structure related to classic Ward guanidinium⋅⋅⋅sulfonate frameworks but with an additional cation/solvent layer. This material includes toluene guests, which are held strongly within the crystal lattice
Zinc(II) coordination polymers with 3-(1H-imidazol-1-yl)propanoate linkers
No full textCoordination polymers of zinc(II) with three readily accessible 3-(1H-imidazol-1-yl)propanoate ligands are prepared by combining aqueous solutions of the ligands and zinc(II) salts, resulting in a precipitation of the respective coordination polymers. While sodium 3-(1H-imidazol-1-yl)propanoate and sodium 3-(2-phenyl-1H-imidazol-1-yl)propanoate initially yield amorphous precipitates that can be converted to crystalline materials upon prolonged heating, the use of sodium 3-(2-methyl-1H-imidazol-1-yl)propanoate results in the immediate formation of a crystalline coordination polymer. All three coordination polymers were structurally characterized by single crystal X-ray diffraction. The crystal water in one coordination polymer could be removed without losing the crystallinity of the sample and this process was studied by infrared spectrometry. The interpretation of the corresponding infrared spectra was supported by theoretical calculations. Furthermore, the solubility in water and buffer solutions as well as the potential porosity of the coordination polymers were investigated, revealing their non-porous character for CO2, N2 and CH4
Light-Driven, Reversible Spatiotemporal Control of Dynamic Covalent Polymers
No full textDynamic covalent polymer networks exhibit a cross-linked structure like conventional thermosets and elastomers, although their topology can be reorganized by thermoactivated bond exchange. This characteristic enables a unique combination of repairability, recyclability and dimensional stability, crucial for a sustainable industrial economy. We herein report the application of a photoswitchable nitrogen superbase for the spatially resolved and reversible control over dynamic bond exchange within a thiol-ene photopolymer. By the exposure to UV or visible light, we successfully gain control over the associative exchange between thioester links and thiol groups, and thereby the macroscopic mechanical material properties, in a locally controlled manner. Consequently, the resulting reorganization of the global network topology enables us to utilize our material for previously unrealizable advanced applications such as spatially resolved, reversible reshaping as well as micro-imprinting over multiple steps. Finally, the presented concept contributes fundamentally to the evolution of dynamic polymers and provides universal applicability in covalent adaptable networks relying on a base-catalyzed exchange mechanism
Delineating a greener synthesis of a key sartan intermediate by photochemical benzylic bromination with electrochemically generated bromine
No full textAn electrochemical bromine generation and photochemical benzylic mono-bromination to afford an advanced brominated intermediate of sartan group of drugs using NaBr/AcOH milieu in an undivided electrochemical cell using graphite and stainless steel electrodes in both batch and continuous flow has been reported for the first time. The reported procedure is simple, green, safe, robust, selective and reproducible. This process has the potential to be developed into a scalable and commercial process for several sartan drug intermediates
Cold Sintering of Halide-in-Oxide Composite Solid-State Electrolytes
No full textAll-solid-state batteries (ASSBs) have attracted increasing attention for next-generation electrochemical energy storage owing to their high energy density and enhanced safety, achieved through the use of non-flammable solid-state electrolytes (SSEs). Oxide-based SSEs, such as Li1.3Al0.3Ti1.7(PO4)3 (LATP), are notable for their high ionic conductivity and excellent chemical and electrochemical oxidation stability. Nevertheless, their brittle mechanical properties and poor interface contact with electrode materials necessitate high-temperature and long-duration sintering or post calcination processes, limiting their processability for real-world applications. Additionally, the formation of secondary phases can detrimentally affect the ionic conductivity of LATP electrolytes. Emerging halide-based SSEs offer reliable deformation for practical processing while maintaining high ionic conductivity. In this work, we report a transient liquid-assisted cold sintering process to integrate oxide-based LATP as the matrix and halide-based Li3InCl6 as the conductive boundary phase into a halide-in-oxide ceramic composite electrolyte at a low processing temperature of 150 ℃. This composite structure significantly reduces interface resistance, effectively addressing ion transport depletion across the boundaries between LATP particles. Consequently, the co-sintered LATP-Li3InCl6 composite SSE exhibits high ionic conductivity of 1.4x10-4 S cm-1 at ambient temperature. Furthermore, the symmetric Li|LATP-Li3InCl6∙nDMF|Li cell demonstrates stable stripping and plating processes for 1600 hours at 55 ℃ (0.1 mA cm-2) and 1200 hours at 100 ℃ (1 mA cm-2). This work represents the first demonstration of ceramic-in-ceramic SSEs that combine the advantages of oxides and halides for high-performance SSBs