High-Resolution NMR of the Hydrogenation Reaction with Parahydrogen in an Inhomogeneous Magnetic Field.

Nuclear magnetic resonance is extremely attractive for operando studies of chemical reactors. However, the heterogeneous catalyst particles placed inside an NMR probe greatly affect the uniformity of the magnetic field. This problem is especially acute when studying heterogeneous hydrogenation processes using parahydrogen.

Novel Anthraquinone Derivatives and Their Complexes with Metal Ions with Anticancer Activity: Structure/Redox and Chelation Activity Correlations.

Some specific anthraquinone derivatives (AQs) are known to be used widely as effective chemotherapeutic agents in the treatment of cancer. However, their fundamental shortcoming is the high rate of cardiotoxicity observed in treated patients, which is thought to be caused by the increase in production of reactive oxygen species (ROS) catalyzed by iron and copper. The development of improved AQs and other anticancer drugs with enhanced efficacy but reduced toxicity remains a high priority.

Copper doped magnetic vortex nanoring based nanotherapeutics for bacterial infection tri-therapy: interplay of magnetic hyperthermia, chemodynamic therapy and photothermal therapy.

Infectious bacteria pose an increasing threat to public health, and hospital-acquired bacterial infections remain a significant challenge for wound healing. In this study, we developed an advanced nanoplatform utilizing copper doped magnetic vortex nanoring coated with polydopamine (Cu-MVNp) based nanotherapeutics for bacterial infection tri-therapy. This multifunctional nanoplatform exhibits remarkable dual-stimulus thermogenic capabilities and Fenton-like peroxidase activity.

Dinuclear Rare-Earth β-Diketiminates with Bridging 3,5-Di-butyl-catecholates: Synthesis, Structure, and Single-Molecule Magnet Properties.

The dinuclear β-diketiminato complex [LClDy(μ-Cl)DyL(THF)] () (L = {2,6-PrCH-NC(Me)CHC(Me)N-2,6-PrCH}) was obtained by reaction of DyCl with KL in a molar ratio of 1:1 and used for the preparation of the mixed-ligand complex [LDy(μ-3,5-Cat)] () by salt metathesis reaction with 3,5-CatK (3,5-Cat -3,5-di--butyl-catecholate). Reactions of 3,5-CatNa with [LLnCl(THF)] (Ln = Dy, Y) ligated with the less bulky ligand L = {2,4,6-MeCH-NC(Me)CHC(Me)N-2,4,6-MeCH} afforded the mixed-ligand THF-containing complexes [LLn(μ-3,5-Cat)(THF)] (Ln = Dy (), Y ()). All new complexes were fully characterized, and the solid-state structures were determined by single-crystal X-ray diffraction.

Unveiling Charge Carrier Dynamics at Organic-Inorganic S-Scheme Heterojunction Interfaces: Insights From Advanced EPR.

Understanding charge carrier transfer at heterojunction interfaces is critical for advancing solar energy conversion technologies. This study utilizes continuous wave (CW), pulse, and time-resolved (TR) electron paramagnetic resonance (EPR) spectroscopy to explore the radical species formed at the TAPA (tris(4-aminophenyl)amine)-PDA (Terephthaldicarboxaldehyde)/ZnInS (TP/ZIS) heterojunction interface. CW and pulse EPR identify stable radical defects localized near the interface, accessible to water molecules.

Consistent theoretical description of nuclear spin long-lived states decay under conditions of reversible ligand-protein binding.

Determining the stability constant of the complex formed by an organic ligand with a protein is the first stage in the screening of new drugs. Nuclear spin long-lived states, in particular the singlet state, can be used to study the reversible binding of ligands to proteins. In a complex with a protein, the spins of the ligand interact with the spins of the protein, the system of protein and ligand nuclei can relax by a dipole-dipole mechanism, and the lifetime of the singlet state is strongly reduced.

Analysis of chemical exchange in iridium N-heterocyclic carbene complexes using heteronuclear parahydrogen-enhanced NMR.

The signal amplification by reversible exchange process (SABRE) enhances NMR signals by unlocking hidden polarization in parahydrogen through interactions with to-be-hyperpolarized substrate molecules when both are transiently bound to an Ir-based organometallic catalyst. Recent efforts focus on optimizing polarization transfer from parahydrogen-derived hydride ligands to the substrate in SABRE. However, this requires quantitative information on ligand exchange rates, which common NMR techniques struggle to provide.

High-field SABRE pulse sequence design for chemically non-equivalent spin systems.

Signal amplification by reversible exchange (SABRE) employs the non-equilibrium spin order of parahydrogen as a source of strong nuclear magnetic resonance (NMR) signal enhancement, with the objective of increasing NMR sensitivity. In SABRE, a parahydrogen molecule and a substrate form a transient polarization transfer complex. Performed within the high magnetic field of an NMR spectrometer, SABRE enables the hyperpolarization of nuclear spins without additional polarizers.

Activation of tert-Butyl Hydroperoxide by Zr(IV) Stabilized by Polyoxotungstate Scaffolds.

Zr-monosubstituted polyoxometalates (Zr-POMs) of the Keggin (BuN)[{PWOZr(μ-OH)}] (Zr-K), Lindqvist (BuN)[{WOZr(μ-OH)}] (Zr-L), and Wells-Dawson (BuN)H[{PWOZr(μ-OH)}] (Zr-WD) structures are capable of heterolytic activation of the environmentally benign oxidant tert-butyl hydroperoxide (TBHP) and catalyze epoxidation of alkenes and oxidation of alcohols to carbonyl compounds. Catalytic activity of corresponding Ti-POMs is much lower. Among Zr-POMs, Zr-K revealed higher epoxide yields.

Expression of concern: Valence tautomeric interconversion of bis-dioxolene cobalt complex with imino-pyridine functionalized by TEMPO moiety in solid solutions with isostructural nickel analogue: phase transitions and monocrystal destruction.

Expression of concern for 'Valence tautomeric interconversion of bis-dioxolene cobalt complex with imino-pyridine functionalized by TEMPO moiety in solid solutions with isostructural nickel analogue: phase transitions and monocrystal destruction' by Michael P. Bubnov , , 2024, , 9151-9160, https://doi.org/10.

Rapid lung ventilation MRI using parahydrogen-induced polarization of propane gas.

Proton-hyperpolarized contrast agents are attractive because they can be imaged on virtually any clinical MRI scanner, which is typically equipped to scan only protons rather than heteronuclei (, anything besides protons, , C, N, Xe, Na, .). Even though the lifetime of the proton spin hyperpolarization is only a few seconds, it is sufficient for inhalation and scanning of proton-hyperpolarized gas media.

Developing Hyperpolarized Butane Gas for Ventilation Lung Imaging.

NMR hyperpolarization dramatically improves the detection sensitivity of magnetic resonance through the increase in nuclear spin polarization. Because of the sensitivity increase by several orders of magnitude, additional applications have been unlocked, including imaging of gases in physiologically relevant conditions. Hyperpolarized Xe gas recently received FDA approval as the first inhalable gaseous MRI contrast agent for clinical functional lung imaging of a wide range of pulmonary diseases.

Mechanism of UV photodegradation of fluoroquinolone antibiotic ciprofloxacin in aqueous solutions.

Mechanism of direct UV photolysis of the zwitterionic and anionic forms of the quinolone antibiotic ciprofloxacin (CIP) was revealed by combination of nanosecond laser flash photolysis, steady-state photolysis coupled with high resolution LC-MS and DFT quantum-chemical calculations. For both forms, the main intermediate is a dissociative triplet state, which loses a fluorine ion to form a triplet carbocation; subsequent solvent attack of the latter leads to the formation of products of hydroxylation both the aromatic ring and the piperazyl substituent. Correspondingly, the quantum yield of photolysis of both CIP forms does not depend on the excitation wavelength, but depends on the concentration of dissolved oxygen.

Investigation of slow magnetic relaxation in a series of 1D polymeric cyclobutane-1,1-dicarboxylates based on LnVIV2 units (Ln = Tb, Dy, Ho, Er, Tm, Yb): rare examples of V-4f single-molecule magnets.

The reactions of VOSO·3HO with Na(cbdc) (cbdc - dianion of cyclobutane-1,1-dicarboxylic acid) and lanthanide(III) nitrates taken in a molar ratio of 1 : 2 : 1 were found to yield a series of isostructural heterometallic compounds [NaLn(VO)(cbdc)(HO)] (1Ln, Ln = Tb, Dy, Ho, Er, Tm, Yb). These compounds are constructed from trinuclear anionic units [Ln(VO)(cbdc)(HO)] ({LnV}) linked by Na ions into 1D polymeric chains. The crystal structures of 1Dy and 1Er were determined by single-crystal X-ray diffraction (XRD), and their isostructurality with 1Tb, 1Ho, 1Tm, and 1Yb was proved by powder X-ray diffraction (PXRD).

Through-bond and through-space radiofrequency amplification by stimulated emission of radiation.

Radio Amplification by Stimulated Emission of Radiation (RASER) is a phenomenon observed during nuclear magnetic resonance (NMR) experiments with strongly negatively polarized systems. This phenomenon may be utilized for the production of very narrow NMR lines, background-free NMR spectroscopy, and excitation-free sensing of chemical transformations. Recently, novel methods of producing RASER by ParaHydrogen-Induced Polarization (PHIP) were introduced.

Origin of Intersystem Crossing in Red-Light Absorbing Bodipy Derivatives: Time-Resolved Transient Optical and Electron Paramagnetic Resonance Spectral Studies with Twisted and Planar Compounds.

We studied the intersystem crossing (ISC) property of red-light absorbing heavy atom-free dihydronaphtho[]-fused Bodipy derivatives (with phenyl group attached at the lower rim via ethylene bridge, taking constrained geometry, i.e., and the half-oxidized product ) and dispiroflourene[]-fused Bodipy () that have a twisted π-conjugated framework.

Control of electronic and exchange coupling by bridge substituents in donor acceptor triads with triptycene bridges.

A series of triads, consisting of a triarylamine electron donor and a perylene diimide electron acceptor which were attached to two different wings of a triptycene bridging unit, was investigated concerning the dynamics of photoinduced charge separation and charge recombination processes with a particular focus on the involved spin-chemical aspects. Attaching electron-donating or electron-withdrawing substituents to the third wing of the triptycene bridge allowed tuning the electron transfer processes. These processes were investigated fs-transient absorption spectroscopy and ns-transient absorption spectroscopy in an external magnetic field.

Effect of the Polyanion Structure on the Mechanism of Alcohol Oxidation with HO Catalyzed by Zr-Substituted Polyoxotungstates.

Zr-monosubstituted polyoxometalates (Zr-POMs) of the Lindqvist (BuN)[{WOZr(μ-OH)}] (), Keggin (BuN)[{PWOZr(μ-OH)}] (), and Wells-Dawson (BuN)KH[{PWOZr}(μ-OH)] () structures catalyze oxidation of alcohols using aqueous hydrogen peroxide as an oxidant. With 1 equiv of HO and 1 mol % of Zr-POM, selectivity toward aldehydes and ketones varied from good to excellent, depending on the alcohol nature. Catalytic activity and attainable substrate conversions strongly depended on the Zr-POM structure and most often decreased in the order > ≫ .

Metabolic stability of the Pallas' spadefoot Pelobates vespertinus under extreme hypoxia.

The Pallas' spadefoot Pelobates vespertinus is a frog species native to eastern Europe and west Siberia. This species resists harsh winter conditions by moving up to 2 m underground. This amphibian is the first species known to withstand extreme air hypoxia.

Temperature Dependence of the Sensitivity of PVDF Pyroelectric Sensors to THz Radiation: Towards Cryogenic Applications.

The application of terahertz (THz) science in industrial technology and scientific research requires efficient THz detectors. Such detectors should be able to operate under various external conditions and conform to existing geometric constraints in the required application. Pyroelectric THz detectors are among the best candidates.

The venom of Habrobracon hebetor induces alterations in host metabolism.

The ability of parasitic wasps to manipulate a host's metabolism is under active investigation. Components of venom play a major role in this process. In the present work, we studied the effect of the venom of the ectoparasitic wasp Habrobracon hebetor on the metabolism of the greater wax moth host (Galleria mellonella).

Contrasting Metallic (Rh) and Carbidic (2D-MoC MXene) Surfaces in Olefin Hydrogenation Provides Insights on the Origin of the Pairwise Hydrogen Addition.

Kinetic studies are vital for gathering mechanistic insights into heterogeneously catalyzed hydrogenation of unsaturated organic compounds (olefins), where the Horiuti-Polanyi mechanism is ubiquitous on metal catalysts. While this mechanism envisions nonpairwise H addition due to the rapid scrambling of surface hydride (H*) species, a pairwise H addition is experimentally encountered, rationalized here based on density functional theory (DFT) simulations for the ethene (CH) hydrogenation catalyzed by two-dimensional (2D) MXene MoC(0001) surface and compared to Rh(111) surface. Results show that ethyl (CH*) hydrogenation is the rate-determining step (RDS) on MoC(0001), yet CH* formation is the RDS on Rh(111), which features a higher reaction rate and contribution from pairwise H addition compared to 2D-MoC(0001).