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1. Predicted hot superconductivity in LaSc ₂ H ₂₄ under pressure

   https://doi.org/10.1073/pnas.2401840121  

   He, Xin-Ling; Zhao, Wenbo; Xie, Yu; Hermann, Andreas; Hemley, Russell J; Liu, Hanyu; Ma, Yanming (June 2024, Proceedings of the National Academy of Sciences)

   The recent theory-driven discovery of a class of clathrate hydrides (e.g., CaH₆, YH₆, YH₉, and LaH₁₀) with superconducting critical temperatures (T_c) well above 200 K has opened the prospects for “hot” superconductivity above room temperature under pressure. Recent efforts focus on the search for superconductors among ternary hydrides that accommodate more diverse material types and configurations compared to binary hydrides. Through extensive computational searches, we report the prediction of a unique class of thermodynamically stable clathrate hydrides structures consisting of two previously unreported H₂₄and H₃₀hydrogen clathrate cages at megabar pressures. Among these phases, LaSc₂H₂₄shows potential hot superconductivity at the thermodynamically stable pressure range of 167 to 300 GPa, with calculatedT_cs up to 331 K at 250 GPa and 316 K at 167 GPa when the important effects of anharmonicity are included. The very high critical temperatures are attributed to an unusually large hydrogen-derived density of states at the Fermi level arising from the newly reported peculiar H₃₀as well as H₂₄cages in the structure. Our predicted introduction of Sc in the La–H system is expected to facilitate future design and realization of hot superconductors in ternary clathrate superhydrides. 

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2. Synthesis and Characterization of Ru(II) Complexes with π‐Expansive Imidazophen Ligands for the Photokilling of Human Melanoma Cells

   https://doi.org/10.1111/php.13177  

   Ghosh, Goutam; Yin, Huimin; Monro, Susan M. A.; Sainuddin, Tariq; Lapoot, Lloyd; Greer, Alexander; McFarland, Sherri A. (January 2020, Photochemistry and Photobiology)

   Abstract Ru(II) complexes were synthesized with π‐expanding (phenyl, fluorenyl, phenanthrenyl, naphthalen‐1‐yl, naphthalene‐2‐yl, anthryl and pyrenyl groups) attached at a 1H‐imidazo[4,5‐f][1,10]phenanthroline ligand and 4,4′‐dimethyl‐2,2′‐bipyridine (4,4′‐dmb) coligands. These Ru(II) complexes were characterized by 1D and 2D NMR, and mass spectroscopy, and studied for visible light and dark toxicity to human malignant melanoma SK‐MEL‐28 cells. In the SK‐MEL‐28 cells, the Ru(II) complexes are highly phototoxic (EC₅₀ = 0.2–0.5 µm) and have low dark toxicity (EC₅₀ = 58–230 µm). The highest phototherapeutic index (PI) of the series was found with the Ru(II) complex bearing the 2‐(pyren‐1‐yl)‐1H‐imidazo[4,5‐f][1,10]phenanthroline ligand. This high PI is in part attributed to the π‐rich character added by the pyrenyl group, and a possible low‐lying and longer‐lived³IL state due to equilibration with the³MLCT state. While this pyrenyl Ru(II) complex possessed a relatively high quantum yield for singlet oxygen formation (Φ_∆ = 0.84), contributions from type‐I processes (oxygen radicals and radical ions) are competitive with the type‐II (¹O₂) process based on effects of added sodium azide and solvent deuteration. 

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3. An Fe( ii ) complex detects hydrogen peroxide with ¹ H and ¹⁹ F magnetic resonance imaging responses

   https://doi.org/10.1039/D5CC04066C  

   Karbalaei, Sana; Franke, Alicja; Zahl, Achim; Pokkuluri, P Raj; Beyers, Ronald J; Ivanović-Burmazović, Ivana; Goldsmith, Christian R (October 2025, Chemical Communications)

   A highly air- and water-stable Fe(ii) complex with a fluorinated ligand has a strong¹⁹F MRI signal but is a poorT₁-weighted¹H MRI contrast agent. Upon oxidation by H₂O₂, the¹⁹F MRI signal decays as the relaxivity for¹H MRI markedly improves. 

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4. Structural Origin of Reversible Li Insertion in Guest‐Free, Type‐II Silicon Clathrates

   https://doi.org/10.1002/aesr.202000114  

   Dopilka, Andrew; Weller, J_Mark; Ovchinnikov, Alexander; Childs, Amanda; Bobev, Svilen; Peng, Xihong; Chan, Candace_K (March 2021, Advanced Energy and Sustainability Research)

   The guest‐free, type‐II Si clathrate (Si₁₃₆) is an open cage polymorph of Si with structural features amenable to electrochemical Li storage. However, the detailed mechanism for reversible Li insertion and migration within the vacant cages of Si₁₃₆is not established. Herein, X‐ray characterization and density functional theory (DFT) calculations are used to understand the structural origin of electrochemical Li insertion into the type‐II clathrate structure. At low Li content, instead of alloying with Si, topotactic Li insertion into the empty cages occurs at ≈0.3 V versus Li/Li⁺with a capacity of ≈231 mAh g⁻¹(corresponding to composition Li₃₂Si₁₃₆). A synchrotron powder X‐ray diffraction analysis of electrodes after lithiation shows evidence of Li occupation within the Si₂₀and Si₂₈cages and a volume expansion of 0.22%, which is corroborated by DFT calculations. Nudged elastic band calculations suggest a low barrier (0.2 eV) for Li migration through interconnected Si₂₈cages, whereas there is a higher barrier for Li migration into Si₂₀cages (2.0 eV). However, if Li is present in a neighboring cage, a cooperative migration pathway with a barrier of 0.65 eV is possible. The results show that the type‐II Si clathrate displays unique electrochemical properties for potential applications as Li‐ion battery anodes. 

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5. Photoswitchable Sol–Gel Transitions and Catalysis Mediated by Polymer Networks with Coumarin‐Decorated Cu ₂₄ L ₂₄ Metal–Organic Cages as Junctions

   https://doi.org/10.1002/anie.201913297  

   Oldenhuis, Nathan J.; Qin, K. Peter; Wang, Shu; Ye, Hong‐Zhou; Alt, Eric A.; Willard, Adam P.; Van Voorhis, Troy; Craig, Stephen L.; Johnson, Jeremiah A. (January 2020, Angewandte Chemie International Edition)

   Abstract Photoresponsive materials that change in response to light have been studied for a range of applications. These materials are often metastable during irradiation, returning to their pre‐irradiated state after removal of the light source. Herein, we report a polymer gel comprising poly(ethylene glycol) star polymers linked by Cu₂₄L₂₄metal–organic cages/polyhedra (MOCs) with coumarin ligands. In the presence of UV light, a photosensitizer, and a hydrogen donor, this “polyMOC” material can be reversibly switched between Cu^II, Cu^I, and Cu⁰. The instability of the MOC junctions in the Cu^Iand Cu⁰states leads to network disassembly, forming Cu^I/Cu⁰solutions, respectively, that are stable until re‐oxidation to Cu^IIand supramolecular gelation. This reversible disassembly of the polyMOC network can occur in the presence of a fixed covalent second network generated in situ by copper‐catalyzed azide‐alkyne cycloaddition (CuAAC), providing interpenetrating supramolecular and covalent networks. 

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