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Fifty-four halopyridines were classified into six series based on halogen substituent positions at ortho, meta, and para to the pyridinic nitrogen. Complexation of these halopyridines with CuCl₂ and CuBr₂ from acetonitrile and ethanol resulted in 158 X-ray structures, including five mixed-ligand-Cu(II) complexes. The dataset provides generalizable insights into coordination structures governed by the halogen atom and position. Bonding and structural analysis across the six halopyridine series, considering bond lengths, angles, and coordination geometries, reveals no more than 19 distinct structural motifs. Across this diverse structural landscape, each halopyridine series adopts a maximum of six coordination structure motifs. The halogen position determines whether crystallization yields single crystals or non-crystalline solids. The ortho-halogens display unique dual properties. Their σ-hole participates in the CX···Cl/BrCu (X = F, Cl, Br, I) halogen bonding, while their electron-belt simultaneously participates in intramolecular CX···Cu interactions, influencing whether ortho-halogens adopt cis- or trans-arrangements in Cu(II) complexes. The density functional theory-computed energies of C–X···Cu interactions vary from 1 to 4 kcal mol⁻¹, depending on the halogen atom identity. Docking studies with human serum albumin reveal stabilizing protein-halopyridine-Cu(II) interactions. These findings provide a framework for the rational design of halopyridine-Cu(II) complexes for applications in materials and bioinorganic chemistry.

Lanthanide(III) complexes are invaluable tools for probing protein structure and dynamics, enabling precise distance measurements and site-specific labeling across electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), and luminescence-based techniques. Designing an optimal lanthanide tag requires high thermodynamic and kinetic stability, minimal linker flexibility, and rapid, quantitative reactivity under mild conditions. Herein, a short series of Ln(III) complexes developed as efficient protein tags is reported, each showing high chemoselectivity for cysteine and enabling labeling in aqueous solution under mild conditions (pH 8, 37 °C). Subtle modifications to the reactive arm of the parent Ln.L1 complex has a pronounced effect on tagging kinetics, with Tb.QuNO achieving >95% labeling of the free amino acid cysteine within 10 min. The more compact and readily synthesized Gd.PyNO also labels efficiently and exhibits a narrow EPR linewidth (3.1 mT average at Q-band across three protein-labeled samples), making it an optimal choice for many EPR applications. These findings highlight the critical role of linker design in lanthanide-based probes for EPR spectroscopy and biological imaging.

The one-step syntheses of highly luminescent Cu(I) dimetallic complexes are reported using Cu(I) salts and the commercially available dppm ligand. Three crystalline phases A–C, obtained either with PF₆⁻ (A and B: [Cu₂(μ₂-dppm)₃](PF₆)₂) or TEF⁻ (C: [Cu₂(μ₂-dppm)₃](TEF)₂) anions, display distinct conformations and crystal packings that strongly influence photophysical properties. All phases show intense solid-state thermally activated delayed fluorescence with room temperature quantum yields of nearly 100%. Emission energies and decay times are modulated by packing effects. Phases A and B exhibit pronounced mechanochromic luminescence upon gentle grinding, while phase C is mechanically insensitive, presumably due to its bulky and flexible counter-anions. Density functional calculation/time-dependent density functional calculations suggest that crystal packing impacts the structural molecular relaxation, in agreement with mechanochromic behaviors. In aerated CH₂Cl₂, these complexes generate singlet oxygen with quantum yield of up to 30%, highlighting their potential as photosensitizers.

Schizochytrium sp., a eukaryotic microalga, biosynthesizes docosahexaenoic acid (DHA; C22:6 ω3) by DHA synthase, which is composed of three subunits (OrfA to C) possessing multiple catalytic domains. The enzyme has three dehydratase (DH) domains, DH_PKS in OrfA and tandem DH_FabA (DH1_FabA and DH2_FabA) domains in OrfC. In this study, the function of each of the DH domains was investigated by in vivo heterologous expression experiments in Escherichia coli and in vitro studies with recombinant truncated OrfA containing DH_PKS and full-length OrfC, in which one of the tandem DH_FabA domains was inactivated by site-directed mutagenesis, and acyl–acyl carrier protein (ACP) intermediates. Following heterologous expression, the DH1_FabA- or DH2_FabA-inactivated enzyme produced no DHA, revealing that both domains are essential, while the DH_PKS-inactivated enzyme showed significantly reduced DHA productivity, confirming that DH_PKS is required for full production of DHA. Moreover, in vitro experiments showed that the C4-ACP substrate was accepted by all of the DHs, but DH_PKS and DH2_FabA showed higher activities than DH1_FabA. DH1_FabA catalyzed two types of reactions: (de)hydrations of C10-, C16-, and C22-ACP substrates and (de)hydrations/2-trans to 2-cis isomerization of C8-, C14-, and C20-ACP substrates. By contrast, DH2_FabA catalyzed (de)hydrations/2-trans to 3-cis isomerization of C6-, C12-, and C18-ACP substrates.

The Front Cover shows a porosity-controlled carbon fiber paper, constructed by electrospinning polyacrylonitrile (PAN) and poly(methyl 2-methacrylate) (PMMA) and carbonization, as a dual-functional electrode substrate for high-sulfur-loading cathodes (6.1 mg cm⁻²) and stabilized lean-lithium anodes (10 mA h cm⁻²). The fabricated lithium–sulfur full cell achieves stable 400 cycles with a low negative-to-positive capacity ratio under lean electrolyte conditions (electrolyte-to-sulfur ratio of 7 μL mg⁻¹). For more information, see the Research Article by C.-C. Wu and S.-H. Chung (DOI: 10.1002/ceur.202500070).

The kinetically controlled supramolecular homo- and heteropolymerization of BDTs and BODIPYs, which feature amido-ester flexible ethylene linkers capable of forming seven-membered intramolecularly hydrogen-bonded pseudocycles that hinder supramolecular polymerization, has been experimentally investigated, revealing a complex assembly behavior. The Cover Feature depicts the energetic scenario in which the monomers are assembled into the corresponding aggregated species. More information can be found in the Research Article by L. Sánchez and co-workers (DOI: 10.1002/ceur.202500231).

The Cover Feature illustrates the propagation of periodic concentration perturbations in chemical reactions. As suggested by the design, these perturbations propagate with distinct phase delays, influenced by reaction rates and the connectivity of reaction pathways. In their Research Article (DOI: 10.1002/ceur.202500266), C. Lefebvre and Q. Duez explain how they harnessed electrospray ionization–mass spectrometry for real-time monitoring of these perturbations in the organocatalytic addition of cyclopentadiene to α,β-unsaturated aldehydes, thereby revealing insights into the kinetics of individual reaction steps.

The Cover Feature illustrates rotary molecular systems (RMSs) activated by visible, near-infrared (NIR), or two-photon (TPA) light. The Review by L. Hortigüela and S. P. Morcillo (DOI: 10.1002/ceur.202500370) analyses how molecular architecture, chiral organization, and excited-state design govern the efficiency, directionality, and thermal behavior of light-driven rotation. It highlights bioinspired designs based on natural chromophores that expand RMS operation toward longer-wavelength activation, enhanced quantum efficiency, and biocompatible functionality.

The Cover Feature perfectly embodies the meaning of the Research Article by A. Leyva-Pérez and co-workers (DOI: 10.1002/ceur.202500217). In the centre is a zeolite with an oasis inside it. In this oasis, a benzyl cation lies in a hammock, relaxing and sunbathing, since even such an unstable cation is stable inside the zeolite. Outside the zeolite, several tropilium ions are ready to enter and become stable as the benzyl cations on the inside.

The Cover Feature shows how the reaction path of CO₂ radical anion addition to N-Ac-enamide was explored by using automated reaction path search methods. Analysis revealed that β-position addition is both kinetically and thermodynamically favored over α-position addition, leading to the selective formation of β-amino acids. This computational prediction was further supported by experimental validation. More information can be found in the Research Article by S. Maeda, T. Mita and co-workers (DOI: 10.1002/ceur.202500184).