Developing Amphetamine Certified Reference Materials: From Batch and Continuous‐Flow Synthesis to Certification Protocol

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Developing Amphetamine Certified Reference Materials: From Batch and Continuous-Flow Synthesis to Certification Protocol

Development of a comprehensive protocol for the production of Certified Reference Materials (CRM) of amphetamine and related compounds from a simple, rapid, and efficient synthesis under batch and continuous-flow conditions are reported in this work, accompanied by the establishment of a certification procedure for these materials through identity checking, homogeneity, stability, and characterization studies.


Abstract

Certified reference materials (CRM) of amphetamine derivatives were produced through a simple, rapid and efficient synthesis in both batch and continuous-flow conditions, accompanied by the development of a comprehensive certification protocol for this class of substances. Our chemistry enabled the synthesis of MDA, MDMA, PMA and PMMA in two steps from safrole and estragole with overall yields of 38–61 % in 48 hours under batch conditions and 61–65 % in 65 minutes under continuous-flow conditions, followed by the development of a certification protocol for these materials through identity checking, homogeneity, stability, and characterization studies. Furthermore, as result of this work, a very pure CRM of MDA.HCl with 99.1±1.4 g/100 g of certified characterization value was produced. Considering the importance of supplying amphetamine calibrants for public security efforts in Forensic Chemistry, the potential therapeutical applications, and responding to the rising demand for the synthesis of CRM, this work presents a pioneering approach for the production of amphetamine and related compounds.

Stimuli‐Responsive, Dynamic Supramolecular Organic Frameworks

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Stimuli-Responsive, Dynamic Supramolecular Organic Frameworks

Supramolecular Organic Frameworks (SOFs) are an emerging class of porous materials based on the self-assembly of organic tectons through non-covalent interactions. For their flexibility, SOFs can show dynamic behaviour undergoing reversible transformations triggered by external physical and/or chemical stimuli, particularly when exposed to guest adsorption in the liquid or gas phase.


Abstract

Supramolecular organic frameworks (SOFs) are a class of three-dimensional, potentially porous materials obtained by the self-assembly of organic building blocks held together by weak interactions such as hydrogen bonds, halogen bonds, π⋅⋅⋅π stacking and dispersion forces. SOFs are being extensively studied for their potential applications in gas storage and separation, catalysis, guest encapsulation and sensing. The supramolecular forces that guide their self-assembly endow them with an attractive combination of crystallinity and flexibility, providing intelligent dynamic materials that can respond to external stimuli in a reversible way. The present review article will focus on SOFs showing dynamic behaviour when exposed to different stimuli, highlighting fundamental aspects such as the combination of tectons and supramolecular interactions involved in the framework formation, structure-property relationship and their potential applications.

Photocatalytic Water Splitting Driven by Surface Plasmon Resonance

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Photocatalytic Water Splitting Driven by Surface Plasmon Resonance

Surface plasmon resonance results in fascinating optical and physical characteristics when interacting with light. This Review summarized recent progress in plasmon-induced water splitting by plasmonic metal–semiconductor catalysts, including developments in the understanding of plasmonic charge separation, distribution and reaction sites, together with devices for enhancing the plasmon-induced water splitting efficiency.


Abstract

Surface plasmon resonance (SPR) in metals results in unique optical properties and photoelectric functions, which are helpful for light harvesting in photocatalysis. Additionally, the plasmon-associated charge transfer process gives a complementary platform to understand the charge dynamics at a fundamental level. This Review focused on the recent developments of water splitting by plasmonic metals/semiconductor photocatalysts. Firstly, the basic characteristics of SPR and the plasmon-enhanced photocatalysis mechanisms including plasmon resonance energy transfer and interfacial charge transfer are introduced, highlighting the recent understanding of the plasmonic electron-hole separation, distribution, and the reaction sites for water splitting. Then, advances in the strategies to improve the quantum efficiency of plasmon-induced water splitting are summarized by considering modulation in metals, interface contacts, and bulk properties of semiconductors. Finally, we discuss future prospects in the development of high-efficiency plasmonic metal/semiconductor photocatalysts for water splitting.

Geopolymer Based Electrodes as New Class of Material for Electrochemical CO2 Reduction

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Geopolymer Based Electrodes as New Class of Material for Electrochemical CO2 Reduction

“Geoploymers offer great potential for reducing CO2 emissions in the construction sector by replacing ordinary cement. Here, we successfully functionalized a geopolymer with tin and applied the hybrid material as an electrode for CO2 electrolysis. Our results show current efficiencies of up to 14 % for formate production….“ Learn more about the story behind the research featured on the front cover in this issue's Cover Profile. Read the corresponding Research Article at 10.1002/celc.202300122.


Abstract

Invited for this issue's Front Cover are the groups of Eddie Koenders and Markus Stöckl. The cover feature illustrates a chimney made of Sn-modified geopolymer-bricks. Functionalized geopolymers can be applied as hybrid material for construction and as an electrode for CO2 electrolysis to formate. The cover was designed by one of the authors Jürgen Schuster and the designer Verena Stöckl. Read the full text of the Research Article at 10.1002/celc.202300122.

Annulation of a Methylenecyclopropane with Cyanoalkenes Catalyzed by Lewis Bases

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The annulation of a methylenecyclopropane with acyl cyanoalkenes using DABCO or quinuclidine as a catalyst was developed to give 2,3-dihydofurans. The stoichiometric amount of the Lewis bases promoted the isomerization of 2,3-dihydrofurans to furans. 1H NMR spectroscopy of the reaction in situ revealed that the methylenecyclopropane is opened by the Lewis base to form a reaction intermediate that is added to the cyanoalkenes.

Nitrogen Heterocycle Synthesis through Hydride Abstraction of Acyclic Carbamates and Related Species: Scope, Mechanism, Stereoselectivity, and Product Conformation Studies

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Acyliminium ions and related species are potent electrophiles that can be quite valuable in the synthesis of nitrogen-containing molecules. This manuscript describes a protocol to form these intermediates through hydride abstractions of easily accessible allylic carbamates, amides, and sulfonamides that avoids the reversibility that is possible in classical condensation-based routes. These intermediates are used in the preparation of a range of nitrogen-containing heterocycles, and in many cases high levels of sterocontrol are observed. Specifically areas of investigation include the impact of chemical structure on oxidation efficiency, the geometry of the intermediate iminium ions, the impact of a substrate stereocenter on stereocontrol, and an examination of transition state geometry.