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1. Electrochemical Ammonia Synthesis in a Proton-Conducting Ceramic Cell: A Parameter Study of an Iron-Based Electrode

   https://doi.org/10.1149/1945-7111/adfc9e  

   Blanck, Philipp; Martin, Etienne P; Schmider, Daniel; Kee, Robert J; Dailly, Julian; Deutschmann, Olaf (August 2025, Journal of The Electrochemical Society)

   Proton-conducting ceramic cells with a Ni-BaCe_0.8Zr_0.1Y_0.1O_3−δ|| BaCe_0.7Zr_0.2Y_0.1O_3−δ|| Fe/BaCe_0.7Zr_0.2Y_0.1O_3−δ-backbone structure were studied in a dual-chamber setup to evaluate the effects of temperature, gas flow, voltage, and electrolyte thickness on electrochemical ammonia synthesis. Three gas feed configurations were tested to differentiate surface reaction mechanisms. Thermodynamic calculations were conducted to evaluate the experimental results in the context of equilibrium limitations. The results showed that proton transport through the electrolyte plays a minor role in the formation of ammonia, while production rates correlated more strongly with applied voltage than with current density. Ammonia synthesis appeared significantly limited by thermodynamics, making an increased hydrogen partial pressure at the cathode essential. A feed configuration supplying only nitrogen to the cathode was ineffective, whereas introducing hydrogen increased the ammonia formation rate from 1.42 × 10⁻¹⁰mol cm⁻²s⁻¹to 3.23 × 10⁻⁹mol cm⁻²s⁻¹at −1.4 V and 500 °C. When proton conduction was suppressed under the same conditions, the rate further increased to 4.32 × 10⁻⁹mol cm⁻²s⁻¹. Varying the cathodic gas flow rate across the 12.57 cm²active area from 8 NL h⁻¹to 20 NL h⁻¹, the ammonia formation rate improved by a factor of 3.1 at −1 V, at both 500 °C and 600 °C. 

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2. Structural insights into supramolecular interactions in isostructural salts of 2,4,6-triaminopyrimidinium with various heterocyclic carboxylates

   https://doi.org/10.1107/S2053229624008787  

   Mohana, Marimuthu; Gomathi, Sundaramoorthy; Thomas_Muthiah, Packianathan; Butcher, Ray J (November 2024, Acta Crystallographica Section C Structural Chemistry)

   2,4,6-Triaminopyrimidine is an interesting and challenging molecule due to the presence of multiple hydrogen-bond donors and acceptors. Its noncovalent interactions with a variety of carboxylic acids provide several supramolecular aggregates with frequently occurring molecular synthons. The present work focuses on the supramolecular interactions of 2,4,6-triaminopyrimidinium 3-(indol-3-yl)propionate–3-(indol-3-yl)propionic acid (1/1), C₄H₈N₅⁺·C₁₁H₁₀NO₂⁻·C₁₁H₁₁NO₂, (I), 2,4,6-triaminopyrimidinium 2-(indol-3-yl)acetate, C₄H₈N₅⁺·C₁₀H₈NO₂⁻, (II), 2,4,6-triaminopyrimidinium 5-bromothiophene-2-carboxylate, C₄H₈N₅⁺·C₅H₂BrO₂S⁻, (III), and 2,4,6-triaminopyrimidinium 5-chlorothiophene-2-carboxylate, C₄H₈N₅⁺·C₅H₂ClO₂S⁻, (IV). All four salts exhibit robust homomeric and heteromericR₂²(8) ring motifs. Salts (I) and (II) develop sextuple [in (I)] and quadruple [in (I) and (II)] hydrogen-bonded arrays through fused-ring motifs. Salt (II) exhibits a rosette-like architecture. Salt (IV) is isostructural and isomorphous with salt (III), exhibiting an identical crystal structure with a different composition and an identical supramolecular architecture. In salts (III) and (IV), a linear hetero-tetrameric motif is formed and, in addition, both salts exhibit halogen–π interactions which enhance the crystal stability. All four salts develop a supramolecular hydrogen-bonded pattern facilitated by several N—H...O and N—H...N hydrogen bonds with multiple furcated donors and acceptors. 

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3. 2-Chloro-4-hydroxyanilinium chloride

   https://doi.org/10.1107/S2414314625008934  

   Bai, Sindhu V; Mensah, Patrick F; Li, Guoqiang; Fronczek, Frank R; Uppu, Rao M (October 2025, IUCrData)

   The title compound, C₆H₇ClNO⁺·Cl⁻, crystallizes in orthorhombic space groupPnmawith both cations and anions lying on a mirror plane in the crystal. The C—Cl distance is 1.7289 (6) Å, the C—N distance is 1.4590 (8) Å, and the C—O distance is 1.3617 (8) Å. Parallel molecules form stacks with interplanar spacing 3.1473 (2) Å, but slipped by 1.97 Å. The NH₃⁺substituent donates three intermolecular hydrogen bonds to chloride ions having N...Cl distances in the range 3.1514 (6)–3.3019 (2) Å, and the OH group donates an intermolecular hydrogen bond to chloride with O...Cl distance 3.0671 (6) Å. The chloro substituent and OH group do not accept hydrogen bonds from NH or OH. 

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4. Tailorable Multi‐Modular Pore‐Space‐Partitioned Vanadium Metal‐Organic Frameworks for Gas Separation

   https://doi.org/10.1002/adma.202403834  

   Wang, Wei; Chen, Yichong; Feng, Pingyun; Bu, Xianhui (July 2024, Advanced Materials)

   Abstract Currently, few porous vanadium metal‐organic frameworks (V‐MOFs) are known and even fewer are obtainable as single crystals, resulting in limited information on their structures and properties. Here this work demonstrates remarkable promise of V‐MOFs by presenting an extensible family of V‐MOFs with tailorable pore geometry and properties. The synthesis leverages inter‐modular synergy on a tri‐modular pore‐partitioned platform. New V‐MOFs show a broad range of structural features and sorption properties suitable for gas storage and separation applications for C₂H₂/CO₂, C₂H₆/C₂H₄, and C₃H₈/C₃H₆. Thec/aratio of the hexagonal cell, a measure of pore shape, is tunable from 0.612 to 1.258. Other tunable properties include pore size from 5.0 to 10.9 Å and surface area from 820 to 2964 m²g⁻¹. With C₂H₂/CO₂selectivity from 3.3 to 11 and high uptake capacity for C₂H₂from 65.2 to 182 cm³g⁻¹(298K, 1 bar), an efficient separation is confirmed by breakthrough experiments. The near‐record high uptake for C₂H₆(166.8 cm³g⁻¹) contributes to the promise for C₂H₆‐selective separation of C₂H₆/C₂H₄. The multi‐module pore expansion enables transition from C₃H₆‐selective to more desirable C₃H₈‐selective separation with extraordinarily high C₃H₈uptake (254.9 cm³g⁻¹) and high separation potential (1.25 mmol g⁻¹) for C₃H₈/C₃H₆(50:50 v/v) mixture. 

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5. Physical and Chemical Properties of Galactic Molecular Gas toward QSO J1851+0035

   https://doi.org/10.3847/1538-4357/ad3d5b  

   Narita, Kanako; Sakamoto, Seiichi; Koda, Jin; Yoshimura, Yuki; Kohno, Kotaro (July 2024, The Astrophysical Journal)

   Abstract Atacama Large Millimeter/submillimeter Array (ALMA) data toward QSO J1851+0035 (l= 33.°498,b= +0.°194) were used to study absorption lines by Galactic molecular gas. We detected 17 species (CO,¹³CO, C¹⁸O, HCO⁺, H¹³CO⁺, HCO, H₂CO, C₂H,c-C₃H,c-C₃H₂, CN, HCN, HNC, CS, SO, SiO, and C) and set upper limits to 18 species as reference values for chemical models. About 20 independent velocity components at 4.7–10.9 kpc from the Galactic center were identified. Their column density and excitation temperature estimated from the absorption study, as well as the CO intensity distributions obtained from the FUGIN survey, indicate that the components withτ≲1 correspond to diffuse clouds or cloud outer edges. Simultaneous multiple-Gaussian fitting of COJ= 1–0 andJ= 2–1 absorption lines shows that these are composed of narrow- and broad-line components. The kinetic temperature empirically expected from the high HCN/HNC isomer ratio (≳4) reaches ≳40 K and the corresponding thermal width accounts for the line widths of the narrow-line components. CN-bearing molecules and hydrocarbons have tight and linear correlations within the groups. The CO/HCO⁺abundance ratio showed a dispersion as large as 3 orders of magnitude with a smaller ratio in a smallerN(HCO⁺) (or lowerA_V) range. Some of the velocity components are detected in single-dish CO emission and ALMA HCO⁺absorption but without corresponding ALMA CO absorption. This may be explained by the mixture of clumpy CO emitters not resolved with the ∼1 pc single-dish beam surrounded by extended components with a very low CO/HCO⁺abundance ratio (i.e., CO-poor gas). 

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