Laws, meta-laws, and hydrogenic symmetries: Adapting Lange's account.

Heat shock protein 90 (Hsp90) is a molecular chaperone that facilitates the folding and maturation of client proteins and is implicated in diseases such as cancer. Of its three domains-N-terminal, middle, and C-terminal-the N-terminal domain (NTD) plays a role in ATP hydrolysis, which is required for the chaperone function of Hsp90 in vivo. Precise information about ATP (and ADP) recognition is useful for designing drugs that target the ATP-binding site. X-ray crystal structures of human Hsp90α-NTD have revealed hydrogen bonds around the ADP-binding site, but the exact hydrogen-bond patterns are unclear, mainly because their structures lack the hydrogen atoms essential for identifying donor and acceptor pairs. Here, we performed neutron structural analyses of human Hsp90α-NTD in both its apo and ADP-bound forms. These structures clarify the hydrogen bonds, including the orientations of water molecules. The neutron structures show that ADP and magnesium binding do not perturb the apo state hydrogen-bond network. The orientation of a water molecule and the position of the Met98 side chain indicate that lone pair-π and CH-π interactions stabilize the binding of the adenine ring. A Hsp90-specific intramolecular hydrogen bond between the ribose moiety and the phosphate implies its contribution to the ATP hydrolysis catalyzed by Hsp90. The precise view of the ADP-binding site indicates that the unperturbed hydration structure plays an important role in ADP recognition.

Distribution of acetyl groups alters the properties of acetylated starch.

Dietary isothiocyanates as redox-active bioactives: A comprehensive review of chemistry.

Photoenzymatic radical hydrocyanoalkylation for the synthesis of γ-stereogenic nitriles.

Integrated quantum chemical and in vitro investigation of Capsanthin antioxidant activity: Mechanism (HAT), cultivar variability, enhanced bioavailability, and key gene expression in peppers.

Efficient removal of N-nitrosodimethylamine and triclosan by nFe@Fe3O4 nanocomposites: Enhanced generation of active hydrogen atoms

Effect of high humidity environment on the time-resolved spectrum of laser-induced air plasma.

Pd/γ-MnO2/Ni foam cathode for efficient electrocatalytic hydrodechlorination of chlorophenols in aqueous solution and wastewater.

Efficient removal of bromate from contaminated water using electrochemical ruthenium/MXene membrane via indirect atomic H* reduction.

The atomic-scale structure of interfacial water plays a central role in electrochemistry, catalysis, friction, and biological engineering. Although atomic force microscopy (AFM) provides high spatial resolution, direct determination of atomic water structures remains challenging due to weak hydrogen contrast and the complex relationship between AFM images and underlying atomic configurations. Here, we develop a closed-loop, physics-informed structural inversion framework for interfacial water from multi-height AFM images. This framework combines conditional generative adversarial learning with an explicit and interpretable structural descriptor that explicitly encodes atomic positions and hydrogen orientations, establishing a direct link between AFM contrast and atomic configuration. Trained on simulated AFM data, the method achieves high accuracy in localizing atomic positions and determining hydrogen orientation. For experimental AFM images, automated preprocessing and structure-aware postprocessing procedures yield physically plausible atomic structures that reproduce the observed AFM contrast after relaxation, despite experimental noise and limited height sampling. Rather than targeting a unique solution, this approach provides a robust initialization for AFM inverse problems, substantially reducing the configurational search space and offering a general strategy applicable to other hydrogen-rich and weakly bonded interfacial systems.

This study demonstrates that catalytic amounts of functionalized pyridines, in the presence of B2nep2 as a diboron reagent, can react with imines to form α-amino radicals. These α-amino radicals can be intramolecularly trapped by alkenyl sulfones through a 6-endo-trig process. According to our experiments and DFT calculations, the sulfonyl moiety plays a crucial role in the cyclization and aromatization processes, which occur in two steps: elimination of the sulfonyl radical and hydrogen atom abstraction, facilitating both aromatization and regeneration of the pyridine–boryl radical. The approach represents a useful application of radical-based methodologies for heterocycle synthesis under mild and catalytic conditions.

Metal-mono(imido) linkages have been known for seven decades, and they are found in transition metal, main group, lanthanide, thorium, and uranium complexes. However, transuranium-mono(imido) complexes remain unknown in any scenario. Here, we present evidence for transient neptunium(V)-mono(imido) complexes. Treatment of [NpIII(TrenTIPS)] (1, TrenTIPS = {N(CH2CH2NSiPri3)3}3-) with N3R (R = SiMe3; 1-adamantyl, Ad) results in N2 evolution and dark purple solutions consistent with the formation of [NpV(TrenTIPS)(NR)] (3NpNR). However, solutions of 3NpNR rapidly turn orange, where for R = SiMe3 the isolated 1:1 products are [NpIV(TrenTIPS){N(H)SiMe3}] (4a) and [NpIV(TrenTIPS-2H){N(H)SiMe3}] (4b, TrenTIPS-2H = {N(CH2CH2NSiPri3)2(NCH2CH2NSiPri2C[Me]=CH2)}3-). The latter contains a dehydrogenated-Pri vinyl functionality accounting for the source of the two amido H atoms. The reaction for R = Ad proceeds similarly, but only [NpIV(TrenTIPS){N(H)Ad}] (5a) could be unequivocally confirmed, though its isolation suggests generality of the imido-to-amido functional group transformation. Complexes 4a/4b exhibit slow relaxation of their magnetization, adding to the small number of transuranium single ion magnets. Experimental and computational analysis suggests that the amido products are formed by C-H activation and two sequential hydrogen atom transfer reactions involving a three-step proton-coupled electron-transfer sequence of H• radical abstraction, electron transfer, then another H• radical abstraction step. In contrast to transient 3NpNR, the 5f2 uranium(IV)-imido complex [K(2.2.2-cryptand)][UIV(TrenTIPS)(NSiMe3)] (8UNSiMe3) is robust, even in boiling THF, suggesting the transience of 5f2 3NpNR is not due to the 5fn-count but the increased effective nuclear charge of neptunium vs uranium. This work highlights divergence of uranium- and neptunium-imido stabilities, emphasizing that the latter is an inherently challenging synthetic target.

Magnetic interactions between localized spins-½ play a central role in quantum magnetism, spin-based quantum computing, and quantum simulation. The range and strength of these interactions are key figures of merit. Here, we probe exchange interactions in pairs of spins-½ introduced by chemisorption of individual hydrogen atoms on graphene. Using scanning tunneling microscopy and inelastic electron tunneling spectroscopy, supported by large-scale mean-field Hubbard calculations, we demonstrate 3 meV exchange couplings at separations beyond 10 nm, surpassing all prior systems. The couplings can be ferro- or antiferromagnetic depending on the relative sublattice arrangement. Real-space mapping of spin excitation amplitudes enables characterization with atomic-resolution. Through atomic manipulation we extend this control to spin trimers, revealing collective spin excitations when pairwise exchange couplings are comparable.

Realizing efficient and selective photocatalytic CO2 reduction (PCO2R) using metal-free organic systems under visible light remains a significant challenge. Here, we report the first metal-free, self-sensitized molecular photocatalyst capable of driving visible-light-induced CO2-to-HCOO- conversion via a consecutive photoinduced electron transfer (ConPET) mechanism. The rationally designed BPI-OMe, featuring an electron-donating group, demonstrates exceptional performance under visible light irradiation, achieving a formate production rate of 27.51mmol g-1h-1 with > 99% selectivity. This outstanding activity stems from its optimized electronic properties: a low excitation energy (2.98eV), a long-lived charge-separated anion radical state (τ = 806.94ns), a high-energy SOMO level (-3.47eV), and strong CO2 binding affinity (-0.147eV). In situ ESR and ultrafast spectroscopic analyses reveal the ConPET process: sequential photon absorption enables electron transfer from ascorbic acid to BPI-OMe, generating BPI-OMe, followed by electron delivery to CO2 to form CO2 -, which is subsequently converted to formate through a hydrogen atom transfer. This work not only represents a breakthrough in metal-free PCO2R but also provides a general molecular design strategy based on multi-photon charge accumulation for enabling challenging solar-to-chemical transformations.

Today a significant number of Gram-negative bacteria have evolved to inactivate traditional antibiotics like penicillin and continue to develop resistance against next-generation antimicrobial drugs at a shocking rate. Taking inspiration from actinobacteria (order Actinomycetales) that make reactive enediynes with a (Z)-1,5-diyn-3-ene core to arm themselves, we report the photoactivation of the enediyne precursor octa-4-en-2,6-diyne-1,8-diamine (EDDA) to kill DH5α cells. To trigger Bergman cyclization of EDDA to make diradicals, we used gold nanorods (AuNRs) of chosen dimensions to act as a light-responsive, heat-generating platform. We put EDDA on AuNRs but also left room for polymyxin B nonapeptide (PMBN) to direct the PMBN/EDDA-loaded AuNRs to the surface of DH5α. PMBN interacts specifically with the lipopolysaccharide (LPS) component of the bacterial outer membrane. Importantly, LPS is highly conserved in the family of Gram-negative bacteria. After binding, we use low-power laser light (λ = 785 nm, 69 mW) to activate heat production at the gold metal surface. This heat triggers formation of a reactive 1,4-didehydrobenzene diradical intermediate that can abstract hydrogen atoms from proteins, lipids, and DNA to destroy their function. Transmission electron microscopy (TEM) shows that bifunctional PMBN/EDDA AuNRs are bound to the bacteria and that this interaction is dependent on the rod-to-cell ratio. Upon exposure to light, >85% of DH5α cells are killed according to LIVE/DEAD cell viability assays. The extent of cell death depends on the cell coverage density of bifunctional rods and the duration of exposure to light. Cell viability experiments were also performed in HEPES buffer. HEPES quenched diradical activity, resulting in unharmed cells. Together, our combined approach of photoactivation and EDDA-mediated radical formation demonstrates the potential of using activable enediynes to eliminate Gram-negative bacteria. In future work, it will be important to assess the effectiveness of this approach against other pathogenic organisms.

Polydopamine (PDA) exhibits unique advantages in the treatment of oxidative damage owing to its melanin-mimetic structure, abundant redox-active functional groups, and excellent biocompatibility. Distinct from conventional antioxidant molecules, PDA-based nanoplatforms can efficiently eliminate reactive oxygen species (ROS) via hydrogen atom transfer and electron transfer mechanisms, while relying on the dynamic redox cycling of catechol/quinone moieties to achieve sustained antioxidant activity. However, systematic summaries of PDA-based antioxidant nanoplatforms remain relatively limited. Therefore, this review provides a comprehensive overview of the antioxidant mechanisms of PDA and its associated physicochemical properties, with particular emphasis on the design strategies of diverse PDA-based nanoplatforms, including solid, mesoporous, hollow, doped, and coated architectures, as well as the effects of structural features, particle size, composition, and surface charge on their antioxidant performance. In addition, recent research progress is systematically categorized around core pathological challenges, including breaking ROS-inflammation feedback loops, overcoming biological delivery barriers, remodeling regenerative microenvironments, and regulating programmed cell death.

A central challenge in polymer development lies in the dilemma between the inherent limitations of each polymer and the diverse requirements for material properties and functionalities in practical applications. Developing new methods to introduce functional groups into polymer backbones could innovatively evolve the way of endowing commodity polymers with new properties. Herein, inspired by the new generation of click chemistry, sulfur(VI) fluoride exchange (SuFEx), we found that SuFEx click chemistry can be effectively bridged with photocatalytic hydrogen atom transfer post-modification of polymers to introduce clickable sulfonyl fluoride groups, thus forging a facile and useful platform for the functionalization, transformation, and diversification of commodity polymers.

The uranyl dication ([UO2]2+) is a highly active photocatalyst for the functionalization of inert Csp3-H bonds by direct hydrogen atom abstraction (HAA). However, photocatalysis by the uranyl ion remains underexplored. Most reports are limited to reactions catalyzed by simple uranyl salts, such as uranyl nitrate [UO2(NO3)2·6H2O] (UNO3). We report a set of uranyl tris(benzoate) complexes 1-R containing strongly coordinating and tunable equatorial ligands that resist photodamage and control access to the oxo groups. These catalyst variants with appropriate aryl substituents undergo catalytic reactions at C-H bonds by HAA. The selectivity and reactivity of this step depend on the ligand framework and are distinct from that of UNO3 or other photoactive oxo complexes, such as decatungstate, that lack ancillary ligands. Finally, consistent with the strong, stable axial U-O bond, reaction with exogenous radical acceptors outcompetes radical rebound, enabling C-C and C-N bond formation from the alkyl radical intermediate. Regioselective alkylation and functionalization of a broad range of substrates results, and this photocatalysis shows that modulation of equatorial ligands on [UO2]2+ can influence the reactivity and selectivity of photocatalytic C-H bond functionalization.

ABSTRACT A central challenge in polymer development lies in the dilemma between the inherent limitations of each polymer and the diverse requirements for material properties and functionalities in practical applications. Developing new methods to introduce functional groups into polymer backbones could innovatively evolve the way of endowing commodity polymers with new properties. Herein, inspired by the new generation of click chemistry, sulfur(VI) fluoride exchange (SuFEx), we found that SuFEx click chemistry can be effectively bridged with photocatalytic hydrogen atom transfer post‐modification of polymers to introduce clickable sulfonyl fluoride groups, thus forging a facile and useful platform for the functionalization, transformation, and diversification of commodity polymers.