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In recent years, European Union member states have hastened energy policy deliberations to address supply and sustainability concerns, placing a significant emphasis on nuclear energy as a means to achieve decarbonization goals. However, despite its significant role in power generation, nuclear energy faces significant challenges linked to fuel reprocessing and waste disposal, that hinder its broader expansion. In this context, the separation of technetium represents a concerning issue. Indeed, technetium's catalytic activity can impede the extraction of uranium, neptunium, and plutonium, affecting waste reprocessing efficiency. Additionally, the stable form of technetium in aerobic conditions, pertechnetate (TcO4−), poses risks of groundwater contamination due to its mobility and solubility. Hence, sensing and separation of TcO4− is imperative for both nuclear fuel processing and minimising radioactive contamination in the environment. However, the binding of TcO4− and its separation from contaminated solutions present challenges due to the acidic (or basic) waste components and the high ionic strength in real matrices. Supramolecular chemists have addressed these issues by designing receptors inspired by molecular recognition principles. This article explores recent advancements and future directions in TcO4− sensing and separation (using extraction and sorption) with a focus on molecular hosts. Metal‐organic receptors will also be discussed. [ABSTRACT FROM AUTHOR]

In recent years, European Union member states have hastened energy policy deliberations to address supply and sustainability concerns, placing a significant emphasis on nuclear energy as a means to achieve decarbonization goals. However, despite its significant role in power generation, nuclear energy faces significant challenges linked to fuel reprocessing and waste disposal, that hinder its broader expansion. In this context, the separation of technetium represents a concerning issue. Indeed, technetium's catalytic activity can impede the extraction of uranium, neptunium, and plutonium, affecting waste reprocessing efficiency. Additionally, the stable form of technetium in aerobic conditions, pertechnetate (TcO4−), poses risks of groundwater contamination due to its mobility and solubility. Hence, sensing and separation of TcO4− is imperative for both nuclear fuel processing and minimising radioactive contamination in the environment. However, the binding of TcO4− and its separation from contaminated solutions present challenges due to the acidic (or basic) waste components and the high ionic strength in real matrices. Supramolecular chemists have addressed these issues by designing receptors inspired by molecular recognition principles. This article explores recent advancements and future directions in TcO4− sensing and separation (using extraction and sorption) with a focus on molecular hosts. Metal‐organic receptors will also be discussed. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of a novel film‐forming organic cage and of its smaller analogue are here described. While the small cage produced single crystals suitable for X‐ray diffraction studies, the large one was isolated as a dense film. Due to its remarkable film‐forming properties, this latter cage could be solution processed into transparent thin‐layer films and mechanically stable dense self‐standing membranes of controllable thickness. Thanks to these peculiar features, the membranes were also successfully tested for gas permeation, reporting a behavior similar to that found with stiff glassy polymers such as polymers of intrinsic microporosity or polyimides. Given the growing interest in the development of molecular‐based membranes, for example for separation technologies and functional coatings, the properties of this organic cage were investigated by thorough analysis of their structural, thermal, mechanical and gas transport properties, and by detailed atomistic simulations. [ABSTRACT FROM AUTHOR]

Two novel imide/imine‐based organic cages have been prepared and studied as materials for the selective separation of CO2 from N2 and CH4 under vacuum swing adsorption conditions. Gas adsorption on the new compounds showed selectivity for CO2 over N2 and CH4. The cages were also tested as fillers in mixed‐matrix membranes for gas separation. Dense and robust membranes were obtained by loading the cages in either Matrimid® or PEEK‐WC polymers. Improved gas‐transport properties and selectivity for CO2 were achieved compared to the neat polymer membranes. [ABSTRACT FROM AUTHOR]

The research on systems able to perform controllable motions under external stimuli arises great interest in the scientific community. Over the years, a library of innovative devices has been produced, classified in different categories according to the molecular or supramolecular level of motion. This minireview aims to highlight some representative studies, in which organic cages are used as building blocks for mechanically interlocked molecules, and in which intramolecular motions are triggered by external input. However, the application of organic cages in the construction of molecular machines is hardly achieved. A good compromise must actually be reached, between flexibility and rigidity of the cage's framework for an effective control of the intra‐ and/or intermolecular motion in the final mechanical device. Our final goal is to stimulate researchers′ curiosity towards cage‐like molecules, so that they take on the challenge of converting a cage into a molecular machine. [ABSTRACT FROM AUTHOR]

Cover Feature: Gas Permeation through Mechanically Resistant Self-Standing Membranes of a Neat Amorphous Organic Cage (Chem. Eur. J. 56/2023) Keywords: gas transport; membranes; molecular materials; organic cages; thin films EN gas transport membranes molecular materials organic cages thin films 1 1 1 10/12/23 20231009 NES 231009 B Gas separation b : A novel organic cage with excellent film-forming tendencies was processed into transparent, mechanically robust, self-standing membranes of controllable thickness. Gas transport, membranes, molecular materials, organic cages, thin films. [Extracted from the article]