Naphthalene (Nap) is widely distributed in the environment and has attracted concern due to its recalcitrance to biodegradation and acute toxic effects. Although several laccases can degrade naphthalene, it remains unclear whether laccase is involved in dioxygenation or ring fission of polycyclic aromatic hydrocarbons (PAHs). We demonstrated that laccase has a naphthalene dioxygenase function with a distinct joint approach to oxygen and the alternative regioselective ring-fission process. These results supplement the family of dioxygenase with laccase, a mild method for the ring opening of aromatics, and an operable scale-up application for remediation from PAH pollution and for regioselective oxygenation and ring opening.

The α-diimine-ligated Mg-Mg-bonded compound [K(THF)3]2[LMg-MgL] (1, L = [(2,6-iPr2C6H3)NC(CH3)]22-) can effectively promote the reduction of pyrazine (Pyz) and derivatives under ambient conditions. Reaction of 1 with 1 equiv of pyrazines (Pyz, 2-MePyz, and 2,5-Me2Pyz) caused two-electron reduction of pyrazines to the dianion (RnPyz2-), which bridges two [LMg(II)] fragments to yield dinuclear complexes [K(THF)2]2[L2-(THF)MgII(μ-RnPyz2-)MgII(THF)L2-] (2-4). When 2 equiv of pyrazine substrates were used, the tetranuclear square complexes, featuring pyrazine radical anions (2,3-Me2Pyz)•- (5) or reductive C-C coupling of Pyz (6), were isolated. Moreover, in the dinuclear complex [L•-MgII(μ-Phz2-)MgIIL•-] (8), the original dianion of α-diimine, L2-, was oxidized to a monoanion (L•-), and phenazine (Phz) was reduced to a dianion.

The oxygen-evolving center (OEC) of photosystem II (PSII) is characterized by a unique Mn4CaO5- or Mn4SrO5-cluster. Understanding the structure-function relationship and the catalytic mechanism of the OEC has been hindered by the lack of a rational model that precisely mimics both the static and dynamic structures of this biological cluster. Herein, we report a series of synthetic Mn4SrO4-clusters that closely mimic the main metal-oxide core, peripheral coordination sphere, redox properties, and the oxidation states of the four Mn ions in the Sr2+-containing OEC. Crystal structural measurements demonstrate that the presence of additional neutral ligands on Sr2+ of the S1 state Mn4SrO4-cluster can significantly modify the geometric conformation of the cluster, whereas the oxidation states and the dominant antiferromagnetic interactions of four Mn ions are largely undisturbed. EPR investigations and DFT calculations on the S2 state Mn4SrO4-cluster demonstrate that the presence of additional neutral ligands can significantly affect the magnetic interactions of the cluster, converting the high-spin state giving rise to a g ≈ 4 EPR signal into a low-spin state with a g = 2 multiline EPR signal. Mass spectroscopic measurements show that a Mn4SrO5-cluster can be generated in solution from the synthetic Mn4SrO4-cluster. These observations provide chemical insights into the functional role of the redox-inactive metal ion (calcium or strontium), dynamic structural changes, and catalytic mechanism of its biological counterpart.

The existence of the magnetic isotope effect in chemical reactions has been recognized for decades. However, its critical significance in influencing chemical processes remains to be substantiated, primarily due to its seemingly minor thermodynamic contributions and its coexistence with mass-dependent isotope effects. In this study, we unequivocally demonstrate that the oxidation of Ni2+ to Ni3+ in a nickel complex can be entirely governed by the 61Ni isotope, despite its low natural abundance. Our findings reveal that such remarkable selectivity is achieved through a careful balance of the kinetics involved in the reaction processes; notably, a well-designed complex with appropriate confinement of the reaction center plays an essential role. These results challenge traditional paradigms in chemistry and pave the way for numerous significant applications.

Fluorescent nanodiamonds (FNDs) hosting nitrogen-vacancy (NV) centers have attracted considerable attention for quantum sensing applications, particularly owing to notable advancements achieved in the field of weak magnetic signal detection in recent years. Here, we report a practical quantum-sensing platform for the controlled production and real-time monitoring of ultra-short-lived reactive free radicals using a double-layered silica modification strategy. An inner dense silica layer preserves the intrinsic properties of NV centers, while an outer porous silica layer facilitates efficient adsorption and stabilization of hydroxyl radicals and their precursor reactants. By doping this mesoporous shell with gadolinium (III) catalysts, we achieve sustained, light-free generation of hydroxyl radicals via catalytic water splitting, eliminating reliance on external precursors. The mechanism underlying this efficient radical generation is discussed in detail. The radical production is monitored in real time and in situ through spin-dependent T1 relaxometry of the NV centers, demonstrating stable and tunable radical fluxes, with concentration tunable across a continuous range from approximately 100 mM to molar levels by adjusting the catalyst condition. This study extends the technical application of nanodiamonds from relaxation sensing to the controlled synthesis of reactive free radicals, thereby providing robust experimental evidence to support the advancement of quantum sensing systems in intelligent manufacturing.

High-efficiency near-infrared (NIR) emitting materials play a crucial role in biomedicine, agriculture, spectroscopy, etc., and the stannates emerge due to their broadband and millisecond-lifetime NIR luminescence. However, their origin has confused the community for 20 years. In this work, we combine first-principles calculations with experiments to explicitly unveil that the unique NIR emission originates from the electronic transitions of trace impurities rather than the previously proposed Sn2+-related self-trapping excitons (STEs) transition in the Sn4+-based compounds, such as AESnO(3) (AE = Ba, Sr, and Ca) perovskites, Ca2RESn2M3O12 (RE = Lu, Y, and Gd; M = Al; RE = La; and M = Ga) and Na2CaSn2Ge3O12 garnets, Mg2SnO4 inverse spinel, and La2Sn2O7 pyrochlore. First-principles calculations provide detailed insights, ruling out the contribution of Sn-related activators to the NIR emission due to their high formation energy and strong electron-phonon coupling but confirming the contribution of Fe3+ or Cr3+ centers by analyses of site occupancies and 3d-3d optical transitions, which effectively explain the experimental emissions and their shift trends in various hosts, as well as the characteristics of luminescence decays. Furthermore, Fe3+-activated BaSnO3 perovskite exhibits decent NIR radioluminescence (similar to 905 nm) and thus demonstrates it has potential as a new type of NIR scintillator. The fresh physical picture in our work thoroughly resolves the origin of stannates' NIR luminescence and extends the radioluminescence to the broadband NIR wavelengths with millisecond-scale lifetimes for time-resolved bioimaging and biosensing.

The low-valent Ni-Ni-bonded compound [((NiL-)-L-I)(2)] (1, L = [(2,6-(Pr2C6H3)-Pr-i)NC(Me)](2)) reacts with a series of multicyclic polyenes through different redox processes, affording seven heteroleptic complexes (2-8) containing nickel, alpha-diimine L, and polyene (or polyenyl) ligands, where all three components exhibit variable oxidation states. The reaction of 1 with 6-(dimethylamino)fulvene or 6,6-dimethylfulvene led to the reductive dimerization of two fulvene molecules, yielding the dinuclear complexes 2 and 3 with a bridging bis-Cp ligand. In contrast, similar reactions with 6,6-diphenylfulvene or pentamethylcyclopentadiene (C5Me5H) only gave the adducts [LNi(eta(4)-6,6-diphenylfulvene)] (4) or [(L-(-))Ni(eta(4)-C5Me5H)] (5) with a neutral polyene molecule. However, the two complexes have different oxidation levels of the nickel center and ligand L, depending on the electronic property of the substrate. By using biphenylene, oxidative addition of a strained C-C bond to nickel occurred to form the biphenyl metallacycle [LNi(mu(2)-Ph-2)] (6). Furthermore, the reaction of 1 with acenaphthylene or C-60 afforded complexes [LNi(eta(2)-acenaphthylene)] (7) and [LNi(eta(2)-C-60)] (8) featuring an eta(2)-bonded neutral polyene. The results provide evidence of the facile electron transfer between the metal and ligands so that the nickel center can adjust its basicity to coordinate effectively with polyene substrates of different pi-acidity.

Odd-electron bonds, i.e., the two-center, three-electron (2c/3e), or one-electron (2c/1e) bonds, have attracted tremendous interest owing to their novel bonding nature and radical properties. Herein, complex [K-(THF)(6)]-[LSn center dot center dot Sn:L] (1), featuring the first and unsupported 2c/1e Sn center dot center dot center dot Sn sigma-bond with a long distance (3.2155(9) angstrom), was synthesized by reduction of stannylene [LSn:] (L = N,N-dpp-o-phenylene diamide) with KC8. The one-electron Sn-Sn bond in 1 was confirmed by the crystal structure, DFT calculations, EPR spectroscopy, and reactivity studies. This compound can be viewed as a stabilized radical by delocalizing to two metal centers and can readily mediate radical reactions such as C-C coupling of benzaldehyde.

An efficient N-H and C(sp3)-H functionalization of aryl ketones with benzylamines/amino acids was developed under mild conditions by virtue of anodic oxidation. A variety of functionalized 2,5-diaryloxazoles were obtained with good to excellent yields. Moreover, some important natural products can be prepared by this method. The reaction features a broad substrate scope, scalability, metal-free and chemical oxidant-free.

Tailoring the host–guest interactions of fluorescent metal–organic frameworks to control UV detection is successful for uranyl phosphonates. Their excellent sensitivity and reliability are analysed, and their mechanism is finely studied.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

>Recently, a study reported on the use of in situ electron paramagnetic resonance(EPR) spectroscopy to investigate two consecutive single-electron processes in polyimide and directly diagnose typical electrochemical reactions of carbonyl-based organic electrode in Li-ion batteries(LIBs). This research offers the important experimental clue for studying speci fic electron conversion routes of multi-electron transfer reactions in LIB materials [1].

Degradation of lignin, a natural macromolecule, by laccase via substrate radicals has been intensively studied. However, the interactions between laccase and DNA have not been thoroughly elucidated to date. In this report, we demonstrate that laccase has the endonuclease-mimetic activity with the sequence preference. The decay of plasmid and cDNA was observed with atomic force microscopy (AFM), electron paramagnetic resonance (EPR) and DNA sequencing. Concomitantly, Image 1 appeared, which produced the DNA lesion. The sequencing results showed that A and AA were the preferred nucleotides flanking the cleaved sites. The hydrogen bonds between complementary base pairs and the base redox potential were responsible for the long-lived charge transfer state within the A-repetitive sequence governing the sequence preference. This discovery implies alternative strategies of surviving the phosphorus stress and resistance to alien DNA in certain species, in which laccase is abundant. These results enrich our understanding of the mechanisms of DNA damage and are important for the interpretation of disease treatment.

The development of functionally distinct catalysts for enantioselective synthesis is a prominent yet challenging goal of synthetic chemistry. In this work, we report a family of chiral N-heterocyclic carbene (NHC)-ligated boryl radicals as catalysts that enable catalytic asymmetric radical cycloisomerization reactions. The radical catalysts can be generated from easily prepared NHC-borane complexes, and the broad availability of the chiral NHC component provides substantial benefits for stereochemical control. Mechanistic studies support a catalytic cycle comprising a sequence of boryl radical addition, hydrogen atom transfer, cyclization, and elimination of the boryl radical catalyst, wherein the chiral NHC subunit determines the enantioselectivity of the radical cyclization. This catalysis allows asymmetric construction of valuable chiral heterocyclic products from simple starting materials.

The catalytic transformation of N2 to NH3 by transition metal complexes is of great interest and importance but has remained a challenge to date. Despite the essential role of vanadium in biological N2 fixation, well-defined vanadium complexes that can catalyze the conversion of N2 to NH3 are scarce. In particular, a V(NxHy) intermediate derived from proton/electron transfer reactions of coordinated N2 remains unknown. Here, we report a dinitrogen-bridged divanadium complex bearing POCOP (2,6-(tBu2PO)2-C6H3) pincer and aryloxy ligands, which can serve as a catalyst for the reduction of N2 to NH3 and N2H4. Low-temperature protonation and reduction of the dinitrogen complex afforded the first structurally characterized neutral metal hydrazido(2-) species ([V]═NNH2), which mediated 15N2 conversion to 15NH3, indicating that it is a plausible intermediate of the catalysis. DFT calculations showed that the vanadium hydrazido complex [V]═NNH2 possessed a N-H bond dissociation free energy (BDFEN-H) of as high as 59.1 kcal/mol. The protonation of a vanadium amide complex ([V]-NH2) with [Ph2NH2][OTf] resulted in the release of NH3 and the formation of a vanadium triflate complex, which upon reduction under N2 afforded the vanadium dinitrogen complex. These transformations model the final steps of a vanadium-catalyzed N2 reduction cycle. Both experimental and theoretical studies suggest that the catalytic reaction may proceed via a distal pathway to liberate NH3. These findings provide unprecedented insights into the mechanism of N2 reduction related to FeV nitrogenase.

Accurate electronic structure calculations might be one of the most anticipated applications of quantum computing.The recent landscape of quantum simulations within the Hartree-Fock approximation raises the prospect of substantial theory and hardware developments in this context.Here we propose a general quantum circuit for M{\o}ller-Plesset perturbation theory (MPPT) calculations, which is a popular and powerful post-Hartree-Fock method widly harnessed in solving electronic structure problems. MPPT improves on the Hartree-Fock method by including electron correlation effects wherewith Rayleigh-Schrodinger perturbation theory. Given the Hartree-Fock results, the proposed circuit is designed to estimate the second order energy corrections with MPPT methods. In addition to demonstration of the theoretical scheme, the proposed circuit is further employed to calculate the second order energy correction for the ground state of Helium atom, and the total error rate is around 2.3%. Experiments on IBM 27-qubit quantum computers express the feasibility on near term quantum devices, and the capability to estimate the second order energy correction accurately. In imitation of the classical MPPT, our approach is non-heuristic, guaranteeing that all parameters in the circuit are directly determined by the given Hartree-Fock results. Moreover, the proposed circuit shows a potential quantum speedup comparing to the traditional MPPT calculations. Our work paves the way forward the implementation of more intricate post-Hartree-Fock methods on quantum hardware, enriching the toolkit solving electronic structure problems on quantum computing platforms.

A metal-freeelectrophotochemical C(sp(3))-H arylationwas developed under mild conditions. This method enables a switchablesynthesis of diaryl alcohols and diaryl alkanes from inactive benzyliccarbons. More importantly, a cheap and safe mediator N-chlorosuccinimide (NCS) was developed, which was employed for thehydrogen atom transfer (HAT) process of the benzylic C-H bond.In addition, this active radical was captured and identified by electronparamagnetic resonance (EPR).

The Nid site coordination microenvironment of a truncated acetyl-coenzyme A synthase has been designed systematically for functional conversion to a Ni-SOD-like enzyme. To this end, the first strategy is to introduce an axial histidine ligand, using mutations F598H, S594H and S594H-GP individually. The resulting three mutants obtained Ni-SOD-like activity successfully, although the catalytic activity was about 10-fold lower than in native Ni-SOD. The second strategy is to mimic the H-bond network in the second sphere coordination microenvironment of the native Ni-SOD. Two mutations based on F598H (EFG-F598H and YGP-F598H) were designed. The successful EFG-F598H exhibited ~3-fold Ni-SOD-like activity of F598H. These designed Ni-SOD-like metalloproteins were characterized by UV/Vis, EPR and Cyclic voltammetry while F598H was also characterized by X-ray protein crystallography. The pH titrations were performed to reveal the source of the two protons required for forming H2O2 in the SOD catalytic reaction. Based on all of the results, a proposed catalytic mechanism for the Ni-SOD-like metalloproteins is presented.

Developing highly efficient catalytic protocols for C-sp(3)-H bond aerobic oxidation under mild conditions is a long-desired goal of chemists. Inspired by nature, a biomimetic approach for the aerobic oxidation of C-sp(3)-H by galactose oxidase model compound CuIIL and NHPI (N-hydroxyphthalimide) was developed. The CuIIL-NHPI system exhibited excellent performance in the oxidation of C-sp(3)-H bonds to ketones, especially for light alkanes. The biomimetic catalytic protocol had a broad substrate scope. Mechanistic studies revealed that the CuI-radical intermediate species generated from the intramolecular redox process of CuIILH2 was critical for O2 activation. Kinetic experiments showed that the activation of NHPI was the rate-determining step. Furthermore, activation of NHPI in the CuIIL-NHPI system was demonstrated by time-resolved EPR results. The persistent PINO (phthalimide-N-oxyl) radical mechanism for the aerobic oxidation of C-sp(3)-H bond was demonstrated.

A new multifunction X-band electron paramagnetic resonance (EPR) spectrometer is designed and produced, which is equipped with a new operation system based on the EPR control and readout system (CRS). The new continuous-wave (cw) dual-mode resonator and the dielectric resonators for respectively the pulsed EPR and transient EPR (trEPR) are designed purposely. The adoption of CRS system improves significantly the integration and expandability. The spectrometer is equipped with cryogen-free EPR variable temperature system with a range of 6~300 K. Thereafter, three typical samples are used to demonstrate the elegant design of the spectrometer by the cw dual-mode EPR, pulsed EPR and trEPR experiments. Perspectively, this design herein will be a criterion or option of the new generation of EPR spectrometer.