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This study explored the interplay between the ligand–surface chemistry of colloidal CsPbBr3 nanowires (NWs) and their optical properties. The ligand equilibrium was probed using nuclear magnetic resonance spectroscopy, and by perturbing the equilibrium via dilution, the gradual removal of ligands from the CsPbBr3 surface was observed. This removal was correlated with an increase in the surface defect density, as suggested by a broadening of the photoluminescence (PL) spectrum, a decrease in the PL quantum yield (PLQY), and quenching of the PL decay. These results highlight similar surface binding between the traditional CsPbBr3 quantum dots and our NWs, thereby expanding the scope of well-established ligand chemistry to a relatively unexplored nanocrystal morphology. By controlling the dilution factor, it was revealed that CsPbBr3 NWs achieve a PLQY of 72% ± 2% and a relatively long average PL lifetime of 400 ± 10 ns, without relying on additional surface passivation techniques, such as ligand exchange. [ABSTRACT FROM AUTHOR]

A new algorithm has been developed to simulate two-dimensional (2D) spectra with correlated anisotropic frequencies faster and more accurately than previous methods. The technique uses finite-element numerical integration on the sphere and an interpolation scheme based on the Alderman–Solum–Grant algorithm. This method is particularly useful for numerical calculations of joint probability distribution functions involving quantities with a parametric orientation dependence. The technique's efficiency also allows for practical least-squares fitting of experimental 2D solid-state nuclear magnetic resonance (NMR) datasets. The simulation method is illustrated for select 2D NMR methods, and a least-squares analysis is demonstrated in the extraction of paramagnetic shift and quadrupolar coupling tensors and their relative orientation from the experimental shifting-d echo 2H NMR spectrum of a NiCl2 · 2D2O salt. [ABSTRACT FROM AUTHOR]

The effect of replacing magnesia by alumina on the pressure-dependent structure of amorphous enstatite was investigated by applying in situ high-pressure neutron diffraction with magnesium isotope substitution to glassy (MgO)0.375(Al2O3)0.125(SiO2)0.5. The replacement leads to a factor of 2.4 increase in the rate-of-change of the Mg–O coordination number with pressure, which increases from 4.76(4) at ambient pressure to 6.51(4) at 8.2 GPa, and accompanies a larger probability of magnesium finding bridging oxygen atoms as nearest-neighbors. The Al–O coordination number increases from 4.17(7) to 5.24(8) over the same pressure interval at a rate that increases when the pressure is above ∼3.5 GPa. On recovering the glass to ambient conditions, the Mg–O and Al–O coordination numbers reduce to 5.32(4) and 4.42(6), respectively. The Al–O value is in accordance with the results from solid-state 27Al nuclear magnetic resonance spectroscopy, which show the presence of six-coordinated aluminum species that are absent in the uncompressed material. These findings explain the appearance of distinct pressure-dependent structural transformation regimes in the preparation of permanently densified magnesium aluminosilicate glasses. They also indicate an anomalous minimum in the pressure dependence of the bulk modulus with an onset that suggests a pressure-dependent threshold for transitioning between scratch-resistant and crack-resistant material properties. [ABSTRACT FROM AUTHOR]

Traditional theories of the nuclear magnetic resonance (NMR) autocorrelation function for intra-molecular dipole pairs assume a single-exponential decay, yet the calculated autocorrelation of realistic systems displays a rich, multi-exponential behavior, resulting in anomalous NMR relaxation dispersion (i.e., frequency dependence). We develop an approach to model and interpret the multi-exponential intra-molecular autocorrelation using simple, physical models within a rigorous statistical mechanical development that encompasses both rotational diffusion and translational diffusion in the same framework. We recast the problem of evaluating the autocorrelation in terms of averaging over a diffusion propagator whose evolution is described by a Fokker–Planck equation. The time-independent part admits an eigenfunction expansion, allowing us to write the propagator as a sum over modes. Each mode has a spatial part that depends on the specified eigenfunction and a temporal part that depends on the corresponding eigenvalue (i.e., correlation time) with a simple, exponential decay. The spatial part is a probability distribution of the dipole pair, analogous to the stationary states of a quantum harmonic oscillator. Drawing inspiration from the idea of inherent structures in liquids, we interpret each of the spatial contributions as a specific molecular mode. These modes can be used to model and predict the NMR dipole–dipole relaxation dispersion of fluids by incorporating phenomena on the molecular level. We validate our statistical mechanical description of the distribution in molecular modes with molecular dynamics simulations interpreted without any relaxation models or adjustable parameters: the most important poles in the Padé–Laplace transform of the simulated autocorrelation agree with the eigenvalues predicted by the theory. [ABSTRACT FROM AUTHOR]

Despite the importance of rhodium complexes in catalysis, and the favorable 100% natural abundance of the spin-1/2 103Rh nucleus, there are few reports of 103Rh nuclear magnetic resonance (NMR) parameters in the literature. In part, this is the consequence of the very low gyromagnetic ratio of 103Rh and its dismal NMR sensitivity. In a previous paper [Harbor-Collins et al., J. Chem. Phys. 159, 104 307 (2023)], we demonstrated an NMR methodology for 1H-enhanced 103Rh NMR and demonstrated an application to the 103Rh NMR of the dirhodium formate paddlewheel complex. In this paper, we employ selective 18O labeling to break the magnetic equivalence of the 103Rh spin pair of dirhodium formate. This allows the estimation of the 103Rh–103Rh spin–spin coupling and provides access to the 103Rh singlet state. We present the first measurement of a 18O-induced 103Rh secondary isotope shift as well as the first instance of singlet order generated in a 103Rh spin pair. The field-dependence of 103Rh singlet relaxation is measured by field-cycling NMR experiments. [ABSTRACT FROM AUTHOR]

Nuclear spin hyperpolarization derived from parahydrogen is a technique for enhancing nuclear magnetic resonance (NMR) sensitivity. The key to hyperpolarization experiments is to achieve rapid transfer and detection to minimize relaxation losses, while also avoiding bubbles or turbulence to guarantee high spectral resolution. In this article, we describe an experimental approach for the interleaved joint modulation of parahydrogen-induced polarization and NMR. We provide schematic diagrams of parahydrogen-based polarizer with in situ high-pressure detection capability and low-field polarization transfer. This approach can help to control the experimental process and acquire experimental information, one example of which is the attainment of the highest hyperpolarization signal intensity at 3.6 s after closing the valve. The polarizer demonstrates in situ detection capability, allowing sample to be restabilized within 0.3 ± 0.1 s and high-resolution NMR sampling under a pressure of 3 bars. Moreover, it can transfer polarized samples from the polarization transfer field to the detection region of NMR within 1 ± 0.3 s for completing signal amplification by reversible exchange experiments. [ABSTRACT FROM AUTHOR]

We present a gauge-origin invariant exact two-component (X2C) approach within a modern density functional framework, supporting meta-generalized gradient approximations such as TPSS and range-separated hybrid functionals such as CAM-B3LYP. The complete exchange-correlation kernel is applied, including the direct contribution of the field-dependent basis functions and the reorthonormalization contribution from the perturbed overlap matrix. Additionally, the finite nucleus model is available for the electron-nucleus potential and the vector potential throughout. Efficiency is ensured by the diagonal local approximation to the unitary decoupling transformation in X2C as well as the (multipole-accelerated) resolution of the identity approximation for the Coulomb term (MARI-J, RI-J) and the seminumerical exchange approximation. Errors introduced by these approximations are assessed and found to be clearly negligible. The applicability of our implementation to large-scale calculations is demonstrated for a tin pincer-type system as well as low-valent tin and lead complexes. Here, the calculation of the Sn nuclear magnetic resonance shifts for the pincer-type ligand with about 2400 basis functions requires less than 1 h for hybrid density functionals. Further, the impact of spin–orbit coupling on the nucleus-independent chemical shifts and the corresponding ring currents of all-metal aromatic systems is studied. [ABSTRACT FROM AUTHOR]

We report measurements of the Meissner screening profile in a Nb (300 nm)/ Al 2 O 3 thin film using 8 Li β -detected nuclear magnetic resonance (β -NMR). The NMR probe 8 Li was ion-implanted into the Nb film at energies ≤ 20 keV, corresponding to mean stopping depths comparable to Nb 's magnetic penetration depth λ. 8 Li 's strong dipole–dipole coupling with the host 93 Nb nuclei provided a "cross-relaxation" channel that dominated in low magnetic fields, which conferred indirect sensitivity to the local magnetic field via the spin-lattice relaxation (SLR) rate 1 / T 1. From a fit of the 1 / T 1 data to a model accounting for its dependence on temperature, magnetic field, and 8 Li + implantation energy, we obtained a magnetic penetration depth λ 0 = 51.5(22) nm, consistent with a relatively short carrier mean-free-path ℓ = 18.7(29) nm typical of similarly prepared Nb films. The results presented here constitute an important step toward using 8 Li β -NMR to characterize bulk Nb samples with engineered surfaces, which are often used in the fabrication of particle accelerators. [ABSTRACT FROM AUTHOR]

In hyperpolarization experiments using parahydrogen, a partially negative line (PNL) of o-H2 is occasionally spotted in the nuclear magnetic resonance (NMR) spectra. This is a manifestation of the two-spin order (TSO) of the proton spins, appearing transiently in o-H2 molecules freshly derived from p-H2. For the TSO to be observable, the o-H2 NMR signal must be split into a doublet. In the literature, the splitting is believed to originate from a slow exchange of the dissolved dihydrogen with the dihydride moiety bound to a catalyst present in the reaction mixture. Because this hypothesis may be debatable, in this work a different splitting mechanism is proposed. It employs a residual dipolar coupling (RDC) between the hydrogen protons, originating from a partial orientation of the H2 molecules by the external magnetic field. The orientation effect is due to the anisotropic magnetic polarizability of H2. In a magnetic field of 11.74 T at room temperature, the currently predicted value of the RDC is −0.0024 Hz. Even such small RDC values are sufficient for the PNL effect to be clearly visible in NMR spectra for physically reasonable levels of the TSO in the o-H2 molecules. For RDC values much smaller than the natural linewidth of o-H2, the theoretical frequency distance between the minimum and maximum of PNL proves to be practically independent of the RDC and is of the order of the linewidth. The calculated amplitudes of the PNLs are proportional to the RDC values used in the calculations. [ABSTRACT FROM AUTHOR]

The nuclear magnetic resonance (NMR) spectroscopy of spin-1/2 nuclei with low gyromagnetic ratio is challenging due to the low NMR signal strength. Methodology for the rapid acquisition of 103Rh NMR parameters is demonstrated for the case of the rhodium formate "paddlewheel" complex R h 2 (H C O 2 ) 4 . A scheme is described for enhancing the 103Rh signal strength by polarization transfer from 1H nuclei, which also greatly reduces the interference from ringing artifacts, a common hurdle for the direct observation of low-γ nuclei. The 103Rh relaxation time constants T1 and T2 are measured within 20 min by using 1H-detected experiments. The field dependence of the 103Rh T1 is measured. The high-field relaxation is dominated by the chemical shift anisotropy mechanism. The 103Rh shielding anisotropy is found to be very large: |Δσ| = 9900 ± 540 ppm. This estimate is compared with density functional theory calculations. [ABSTRACT FROM AUTHOR]

Pandit[1] provides a review on the application of magic angle spinning nuclear magnetic resonance (NMR) spectroscopy and related techniques, with which it is possible to access the motion of proteins, pigments, and lipids on sub-nanoseconds to millisecond timescales on very different length scales ranging from solubilized complexes to whole cells. Remarkably, the spectral density includes 50 high-frequency vibrational modes per pigment, besides a low-frequency part characterizing the pigment-protein coupling. Using this technique, excitation energy transfer between the bacteriochlorophyll a pigments of the LH2 complex of purple bacteria is studied. Two important points dealt with in the present Special Topic issue on "Photosynthetic Light-Harvesting and Energy Conversion" are the following: (i) Pigment-protein complexes undergo conformational transitions on many different timescales that include transitions between functionally relevant modes of light harvesting and photoprotection. [Extracted from the article]

The structure of zinc aluminosilicate glasses with the composition (ZnO)x(Al2O3)y(SiO2)1−x−y, where 0 ≤ x < 1, 0 ≤ y < 1, and x + y < 1, was investigated over a wide composition range by combining neutron and high-energy x-ray diffraction with 27Al magic angle spinning nuclear magnetic resonance spectroscopy. The results were interpreted using an analytical model for the composition-dependent structure in which the zinc ions do not act as network formers. Four-coordinated aluminum atoms were found to be in the majority for all the investigated glasses, with five-coordinated aluminum atoms as the main minority species. Mean Al–O bond distances of 1.764(5) and 1.855(5) Å were obtained for the four- and five-coordinated aluminum atoms, respectively. The coordination environment of zinc was not observed to be invariant. Instead, it is dependent on whether zinc plays a predominantly network-modifying or charge-compensating role and, therefore, varies systematically with the glass composition. The Zn–O coordination number and bond distance were found to be 4.36(9) and 2.00(1) Å, respectively, for the network-modifying role vs 5.96(10) and 2.08(1) Å, respectively, for the charge-compensating role. The more open coordination environment of the charge-compensator is related to an enhanced probability of zinc finding bridging oxygen atoms as nearest-neighbors, reflecting a change in the connectivity of the glass network comprising four-coordinated silicon and aluminum atoms as the alumina content is increased. [ABSTRACT FROM AUTHOR]

Stretching or compressing hydrogels creates anisotropic environments that lead to motionally averaged alignment of embedded guest quadrupolar nuclear spins such as 23Na+. These distorted hydrogels can elicit a residual quadrupolar coupling that gives an oscillation in the trajectories of single quantum coherences (SQCs) as a function of the evolution time during a spin-echo experiment. We present solutions to equations of motion derived with a Liouvillian superoperator approach, which encompass the coherent quadrupolar interaction in conjunction with relaxation, to give a full analytical description of the evolution trajectories of rank-1 ( T ^ 1 ± 1 ), rank-2 ( T ^ 2 ± 1 ), and rank-3 ( T ^ 3 ± 1 ) SQCs. We performed simultaneous numerical fitting of the experimental 23Na nuclear magnetic resonance (NMR) spectra and rank-2 ( T ^ 2 ± 1 ) and rank-3 ( T ^ 3 ± 1 ) SQC evolution trajectories measured in double and triple quantum filtered experiments, respectively. We estimated values of the quadrupolar coupling constant CQ, rotational correlation time τC, and 3 × 3 Saupe order matrix. We performed simultaneous fitting of the analytical expressions to the experimental data to estimate values of the quadrupolar coupling frequency ωQ/2π, residual quadrupolar coupling ω Q / 2 π , and corresponding spherical order parameter S 0 * , which showed a linear dependence on the extent of uniform hydrogel stretching and compression. The analytical expressions were completely concordant with the numerical approach. The insights gained here can be extended to more complicated (biological) systems such as 23Na+ bound to proteins or located inside and outside living cells in high-field NMR experiments and, by extension, to the anisotropic environments found in vivo with 23Na magnetic resonance imaging. [ABSTRACT FROM AUTHOR]

The quantum adiabatic method, which maintains populations in their instantaneous eigenstates throughout the state evolution, is an established and often a preferred choice for state preparation and manipulation. Although it minimizes the driving cost significantly, its slow speed is a severe limitation in noisy intermediate-scale quantum era technologies. Since adiabatic paths are extensive in many physical processes, it is of broader interest to achieve adiabaticity at a much faster rate. Shortcuts to adiabaticity techniques, which overcome the slow adiabatic process by driving the system faster through non-adiabatic paths, have seen increased attention recently. The extraordinarily long lifetime of the long-lived singlet states (LLS) in nuclear magnetic resonance (NMR), established over the past decade, has opened several important applications ranging from spectroscopy to biomedical imaging. Various methods, including adiabatic methods, are already being used to prepare LLS. In this article, we report the use of counterdiabatic driving (CD) to speed up LLS preparation with faster drives. Using NMR experiments, we show that CD can give stronger LLS order in shorter durations than conventional adiabatic driving. [ABSTRACT FROM AUTHOR]

The coherent transfer of electron spin polarization to nuclei by means of a microwave pulse sequence is a promising new approach to enhancing the sensitivity of solid-state nuclear magnetic resonance (NMR). The development of pulse sequences for dynamic nuclear polarization (DNP) of bulk nuclei is far from complete, as is the understanding of what makes a good DNP sequence. In this context, we introduce a new sequence, termed Two-Pulse Phase Modulation (TPPM) DNP. We provide a general theoretical description for electron–proton polarization transfer by periodic DNP pulse sequences and find it in excellent agreement with numerical simulations. In experiments at 1.2 T, TPPM DNP generates a higher gain in sensitivity than existing sequences XiX (X-inverse-X) and TOP (Time-Optimized Pulsed) DNP but does so at relatively high nutation frequencies. In contrast, we find that the XiX sequence performs very well at nutation frequencies as low as 7 MHz. A combination of theoretical analysis and experimental investigation makes clear that fast electron–proton polarization transfer, due to a well-preserved dipolar coupling in the effective Hamiltonian, correlates with a short build-up time of the dynamic nuclear polarization of the bulk. Experiments further show that the performances of XiX and TOP DNP are affected differently by the concentration of the polarizing agent. These results constitute important reference points for the development of new and better DNP sequences. [ABSTRACT FROM AUTHOR]

To investigate the novel quantum dynamic behaviors of magnetic materials that arise from complex spin–spin interactions, it is necessary to probe the magnetic response at a speed greater than the spin-relaxation and dephasing processes. Recently developed two-dimensional (2D) terahertz magnetic resonance (THz-MR) spectroscopy techniques use the magnetic components of laser pulses, and this allows investigation of the details of the ultrafast dynamics of spin systems. For such investigations, quantum treatment—not only of the spin system itself but also of the environment surrounding the spin system—is important. In our method, based on the theory of multidimensional optical spectroscopy, we formulate nonlinear THz-MR spectra using an approach based on the numerically rigorous hierarchical equations of motion. We conduct numerical calculations of both linear (1D) and 2D THz-MR spectra for a linear chiral spin chain. The pitch and direction of chirality (clockwise or anticlockwise) are determined by the strength and sign of the Dzyaloshinskii–Moriya interaction (DMI). We show that not only the strength but also the sign of the DMI can be evaluated through the use of 2D THz-MR spectroscopic measurements, while 1D measurements allow us to determine only the strength. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) photolysis of nitrite ions (NO2−) in aqueous solutions produces a suite of radicals, viz., NO·, O−, ·OH, and ·NO2. The O− and NO· radicals are initially formed from the dissociation of photoexcited NO2−. The O− radical undergoes reversible proton transfer with water to generate ·OH. Both ·OH and O− oxidize the NO2− to ·NO2 radicals. The reactions of ·OH occur at solution diffusion limits, which are influenced by the nature of the dissolved cations and anions. Here, we systematically varied the alkali metal cation, spanning the range from strongly to weakly hydrating ions, and measured the production of NO·, ·OH, and ·NO2 radicals during UV photolysis of alkaline nitrite solutions using electron paramagnetic resonance spectroscopy with nitromethane spin trapping. Comparing the data for the different alkali cations revealed that the nature of the cation had a significant effect on production of all three radical species. Radical production was inhibited in solutions with high charge density cations, e.g., lithium, and promoted in solutions containing low charge density cations, e.g., cesium. Through complementary investigations with multinuclear single pulse direct excitation nuclear magnetic resonance (NMR) spectroscopy and pulsed field gradient NMR diffusometry, cation-controlled solution structures and extent of NO2− solvation were determined to alter the initial yields of ·NO and ·OH radicals as well as alter the reactivity of NO2− toward ·OH, impacting the production of ·NO2. The implications of these results for the retrieval and processing of low-water, highly alkaline solutions that comprise legacy radioactive waste are discussed. [ABSTRACT FROM AUTHOR]

In hyperpolarization experiments using parahydrogen, a partially negative line (PNL) of o-H2 is occasionally spotted in the nuclear magnetic resonance (NMR) spectra. This is a manifestation of the two-spin order (TSO) of the proton spins, appearing transiently in o-H2 molecules freshly derived from p-H2. For the TSO to be observable, the o-H2 NMR signal must be split into a doublet. In the literature, the splitting is believed to originate from a slow exchange of the dissolved dihydrogen with the dihydride moiety bound to a catalyst present in the reaction mixture. Because this hypothesis may be debatable, in this work a different splitting mechanism is proposed. It employs a residual dipolar coupling (RDC) between the hydrogen protons, originating from a partial orientation of the H2 molecules by the external magnetic field. The orientation effect is due to the anisotropic magnetic polarizability of H2. In a magnetic field of 11.74 T at room temperature, the currently predicted value of the RDC is −0.0024 Hz. Even such small RDC values are sufficient for the PNL effect to be clearly visible in NMR spectra for physically reasonable levels of the TSO in the o-H2 molecules. For RDC values much smaller than the natural linewidth of o-H2, the theoretical frequency distance between the minimum and maximum of PNL proves to be practically independent of the RDC and is of the order of the linewidth. The calculated amplitudes of the PNLs are proportional to the RDC values used in the calculations. [ABSTRACT FROM AUTHOR]

Nuclear magnetic resonance (NMR) spectroscopy is one of the indispensable techniques in chemistry because it enables us to obtain accurate information on the chemical, electronic, and dynamic properties of molecules. Computational simulation of the NMR spectra requires time-consuming density functional theory (DFT) calculations for an ensemble of molecular conformations. For large flexible molecules, it is considered too high-cost since it requires time-averaging of the instantaneous chemical shifts of each nuclear spin across the conformational space of molecules for NMR timescales. Here, we present a Gaussian process/deep kernel learning-based machine learning (ML) method for enabling us to predict, average in time, and analyze the instantaneous chemical shifts of conformations in the molecular dynamics trajectory. We demonstrate the use of the method by computing the averaged 1H and 13C chemical shifts of each nuclear spin of a trefoil knot molecule consisting of 24 para-connected benzene rings (240 atoms). By training ML model with the chemical shift data obtained from DFT calculations, we predicted chemical shifts for each conformation during dynamics. We were able to observe the merging of the time-averaged chemical shifts of each nuclear spin in a singlet 1H NMR peak and two 13C NMR peaks for the knot molecule, in agreement with experimental measurements. The unique feature of the presented method is the use of the learned low-dimensional deep kernel representation of local spin environments for comparing and analyzing the local chemical environment histories of spins during dynamics. It allowed us to identify two groups of protons in the knot molecule, which implies that the observed singlet 1H NMR peak could be composed of the contributions from protons with two distinct local chemical environments. [ABSTRACT FROM AUTHOR]

Summary: Iron (Fe) is crucial for metabolic functions of living organisms. Plants access occluded Fe through interactions with rhizosphere microorganisms and symbionts. Yet, the interplay between Fe addition and plant–mycorrhizal interactions, especially the molecular mechanisms underlying mycorrhiza‐assisted Fe processing in plants, remains largely unexplored.We conducted mesocosms in Pinus plants inoculated with different ectomycorrhizal fungi (EMF) Suillus species under conditions with and without Fe coatings. Meta‐transcriptomic, biogeochemical, and X‐ray fluorescence imaging analyses were applied to investigate early‐stage mycorrhizal roots.While Fe addition promoted Pinus growth, it concurrently reduced mycorrhiza formation rate, symbiosis‐related metabolites in plant roots, and aboveground plant carbon and macronutrient content. This suggested potential trade‐offs between Fe‐enhanced plant growth and symbiotic performance. However, the extent of this trade‐off may depend on interactions between host plants and EMF species. Interestingly, dual EMF species were more effective at facilitating plant Fe uptake by inducing diverse Fe‐related functions than single‐EMF species. This subsequently triggered various Fe‐dependent physiological and biochemical processes in Pinus roots, significantly contributing to Pinus growth. However, this resulted in a greater carbon allocation to roots, relatively reducing the aboveground plant carbon content.Our study offers critical insights into how EMF communities rebalance benefits of Fe‐induced effects on symbiotic partners. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Eight new guaiane‐type sesquiterpenoid trimers, artemsieverolactones A—H, possessing unprecedented scaffolds via biocatalyzed [4+2] Diels−Alder cycloaddition reactions were identified from Artemisia sieversiana. Their structures were determined by comprehensive spectroscopic data, single‐crystal X‐ray diffraction analyses, and ECD calculations. In terms of structure, artemsieverolactones A—H are first examples of sesquiterpenoid trimers from guaiane‐type sesquiterpenoid through four different [4+2] Diels−Alder cycloaddition models. Antihepatic fibrosis assay suggested that five compounds exhibited activity against HSC‐LX2 with IC50 values ranging from 37.8 to 117.1 μmol/L. The most active artemsieverolactone B (2) displayed significant inhibitory activity against HSC‐LX2 with IC50 value of 37.8 μmol/L, which was 3 times more active than the positive drug silybin (IC50, 139.7 μmol/L). Preliminary mechanism study revealed that artemsieverolactone B could inhibit the deposition of human collagen type I (Col I), human hyaluronic acid (HA), and human laminin (HL) with IC50 values of 40.4 μmol/L (Col I), 55.1 μmol/L (HL), 47.3 μmol/L (HA), which was 2 to 3‐fold more potent than silybin. [ABSTRACT FROM AUTHOR]

Three new examples of covalently linked bis(3-pyrrolyl BODIPY)s were prepared as key precursors for the synthesis of rare hexapyrrolic ligands by treating readily available 3-pyrrolyl BODIPY with different ketones under acid-catalyzed conditions. The new bis(3-pyrrolyl BODIPY) complexes were thoroughly characterized using HR-MS, NMR spectroscopy, absorption, fluorescence, electrochemistry, and theoretical methods. The bis(3-pyrrolyl BODIPY) complexes were treated with AlCl3 in CH3OH at reflux for 2 h to demask BF2 units to afford novel hexapyrrolic ligands. The hexapyrrolic ligands without isolating were treated with Zn(CH3COO)2 in CH3CN at room temperature for 2 h followed by repeated recrystallization to afford crystalline bis-Zn(II) complexes. The X-ray crystallographic structure obtained for one of the bis-Zn(II) complexes revealed that it was a double-stranded bimetallic helicate containing two non-superimposable M and P enantiomers in equal amounts, which were nonseparable. Each Zn(II) ion in the bis-Zn helicate complexes was coordinated to four nitrogen atoms of two dipyrrin units from two hexapyrrolic ligands in a distorted tetrahedral geometry. The distance between two Zn(II) ions (Zn1–Zn2) in bis-Zn(II) helicate was 8.211 Å, which was longer than the distance between two Cu(II) ions (Cu1–Cu2) in our previously reported bis-Cu(II) helicate complex (7.330 Å). NMR studies indicated that the bis-Zn(II) complexes were highly symmetric. The bis-Zn(II) helicates showed broad absorption bands in the region of 400–700 nm and were nonfluorescent. DFT/TD-DFT studies were in agreement with the experimental observations. [ABSTRACT FROM AUTHOR]

Existing modelling tools, developed to aid the design of efficient molecular wires and to better understand their charge‐transport behaviour and mechanism, have limitations in accuracy and computational cost. Further research is required to develop faster and more precise methods that can yield information on how charge transport properties are impacted by changes in the chemical structure of a molecular wire. In this study, we report a clear semilogarithmic correlation between charge transport efficiency and nuclear magnetic resonance chemical shifts in multiple series of molecular wires, also accounting for the presence of chemical substituents. The NMR data was used to inform a simple tight‐binding model that accurately captures the experimental single‐molecule conductance values, especially useful in this case as more sophisticated density functional theory calculations fail due to inherent limitations. Our study demonstrates the potential of NMR spectroscopy as a valuable tool for characterising, rationalising, and gaining additional insights on the charge transport properties of single‐molecule junctions. [ABSTRACT FROM AUTHOR]

A phytochemical investigation on the 80% EtOH extract of the fruiting bodies of Ganoderma tsugae resulted into the isolation of two previously undescribed lanostane triterpenoids, 7,11-dioxo-3β-acetyloxy-26,27-dihydroxy-lanosta-8,24-diene (1) and 7,20-dioxo-3β-acetyloxy-11β,15α-dihydroxy-22,23,24,25,26,27-hexanorlanosta-8-ene (2), togeher with one known lanostane triterpenoid ganodermanontriol (3). Structural elucidation of all the compounds were performed by spectral methods such as 1D and 2D (1H-1H COSY, HMQC, and HMBC) NMR spectroscopy. All the triterpenoids were in vitro evaluated for their antibacterial activities against six pathogenic microorganisms. Compound 3 exhibited some activities against three Gram positive bacteria with MIC values less than 30 μg/ml. [ABSTRACT FROM AUTHOR]

Two oxygenated ergostane-type steroids including one new compound, 3β-hydroxy-5α,6β-methoxyergosta-7,22-dien-15-one (1) along with a known analogue ergosta-6,22-dien-3β,5α,8α-triol (2) were isolated from the crude extracts of the marine sponge-derived fungus Aspergillus sp. Their structures were elucidated on the basis of combined NMR and MS spectroscopic methods. Compound 1 was a marine ergostane-type steroid with two methoxy groups at C-5 and C-6, respectively. These oxygenated ergostane-type steroids were evaluated for their antibacterial activities against human or aquatic pathogens. Among them, compound 1 exhibited antibacterial activity against Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

New dammarane-type triterpenoid saponin, named 22(R)-notoginsenoside Ab1 (1), together with thirteen known dammarane-type triterpenoid saponins (2-14) was isolated from the EtOH extract of black ginseng and their structures were elucidated on the basis of one- and two-dimensional NMR (including 1H-NMR, 13C-NMR, HSQC, HMBC, ROESY) and calculated ECD. Among them, compounds 1-2 and 6-8 were isolated for the first time from ginseng and black ginseng. Besides, the absolute structure of 22(R)- and 22(S)- notoginsenoside Ab1 were distinguished by ECD for the first time. [ABSTRACT FROM AUTHOR]

Background Dysregulated energy metabolism is a recently discovered key feature of autosomal dominant polycystic kidney disease (ADPKD). Cystic cells depend on glucose and are poorly able to use other energy sources such as ketone bodies. Raising ketone body concentration reduced disease progression in animal models of polycystic kidney diseases. Therefore, we hypothesized that higher endogenous plasma beta-hydroxybutyrate (BHB) concentrations are associated with reduced disease progression in patients with ADPKD. Methods We analyzed data from 670 patients with ADPKD participating in the Developing Intervention Strategies to Halt Progression of ADPKD (DIPAK) cohort, a multi-center prospective observational cohort study. BHB was measured at baseline using nuclear magnetic resonance spectroscopy. Participants were excluded if they had type 2 diabetes, were using disease-modifying drugs (e.g. tolvaptan, somatostatin analogs), were not fasting or had missing BHB levels, leaving 521 participants for the analyses. Linear regression analyses were used to study cross-sectional associations and linear mixed-effect modeling for longitudinal associations. Results Of the participants, 61% were female, with an age of 47.3 ± 11.8 years, a height-adjusted total kidney volume (htTKV) of 834 [interquartile range (IQR) 495–1327] mL/m and an estimated glomerular filtration rate (eGFR) of 63.3 ± 28.9 mL/min/1.73 m2. The median concentration of BHB was 94 (IQR 68–147) µmol/L. Cross-sectionally, BHB was associated neither with eGFR nor with htTKV. Longitudinally, BHB was positively associated with eGFR slope {B = 0.35 mL/min/1.73 m2 [95% confidence interval (CI) 0.09 to 0.61], P  = .007}, but not with kidney growth. After adjustment for potential confounders, every doubling in BHB concentration was associated with an improvement in the annual rate of eGFR by 0.33 mL/min/1.73 m2 (95% CI 0.09 to 0.57, P  = .008). Conclusion These observational analyses support the hypothesis that interventions that raise BHB concentration could reduce the rate of kidney function decline in patients with ADPKD. [ABSTRACT FROM AUTHOR]

This research introduces an eco‐friendly and innovative technique for efficiently producing p‐tolylmethanol derivatives 4(a–k) using electro‐organic synthesis based on the Grignard reaction. By employing electrochemical methods, this approach offers several advantages, including enhanced reaction efficiency and reduced environmental impact. The process involves the electrochemical generation of the Grignard reagent, followed by its reaction with appropriate substrates to yield the desired p‐tolylmethanol derivatives. Our team optimized various reaction parameters like choice of solvent, electrode material, and reaction conditions to achieve high yields and selectivity. The developed electro‐organic method demonstrated outstanding efficiency and presents a fresh and environmentally conscious approach to synthesizing p‐tolylmethanol derivatives from benzaldehyde 1(a–e) and bromobenzene 2(a–h) via the Grignard reaction, yielding excellent results (85–93%). The resulting compounds were comprehensively characterized using melting point, 1H NMR spectroscopy, and CHN analysis to verify their structures. This electro‐organic approach holds significant potential as a sustainable strategy for synthesizing valuable organic compounds. [ABSTRACT FROM AUTHOR]

Background: Stroke is a significant global cause of mortality and morbidity, and post-stroke cognitive impairment (PSCI) affects up to half of stroke patients. Despite the availability of pharmacological and non-pharmacological interventions, there is a lack of definitive effective treatments for PSCI. Non-invasive brain stimulation, particularly intermittent theta burst stimulation (iTBS), has emerged as a promising therapy for the treatment of PSCI. Objective: This systematic review and meta-analysis aimed to evaluate the efficacy and safety of iTBS in enhancing cognitive function among patients with PSCI. Methods: A comprehensive search was conducted across multiple databases, including PubMed, Web of Science, Scopus, Cochrane Library, and CNKI, to identify relevant randomized controlled trials published before April 2023. The primary outcome measured changes in global cognitive scales, while the secondary outcomes focused on improvements in attention, orientation, visual-spatial perception, and activities of daily living. Results: The meta-analysis encompassed six studies involving 325 patients. The results demonstrated that iTBS led to a significant improvement in global cognitive scales (SMD = 1.12, 95% CI = [0.59 to 1.65], P < 0.0001), attention (SMD = 0.48, 95% CI [0.13 to 0.82], P = 0.007), visual perception (SMD = 0.99, 95% CI [0.13 to 1.86], P = 0.02), and activities of daily living (SMD = 0.82, 95% CI [0.55 to 1.08], P < 0.00001). However, there was no significant effect on orientation (SMD = 0.36, 95% CI [− 0.04 to 0.76], P = 0.07). Subgroup analysis based on the number of sessions was conducted, revealing a significant improvement in global cognition among patients with PSCI across the three categories (10 sessions, 20 sessions, and 30 sessions) with no between-group difference (P = 0.28). None of the included studies reported any serious adverse effects. Conclusion: In conclusion, iTBS appears to be a safe and effective non-invasive treatment that can enhance the cognitive abilities and daily living skills of patients with post-stroke cognitive impairment. However, our conclusion is constrained by the limited number of studies. Further high-quality, large-sample RCTs with extended follow-up periods are necessary to validate these findings. Integrating iTBS with brain imaging techniques, such as functional near-infrared spectroscopy and functional magnetic resonance, could aid in understanding the mechanism of iTBS action. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the differences between resting and active thalamic neurometabolite levels and inhibitory function in obsessive compulsive disorder (OCD) patients with poor sleep quality (PSQ was defined as Pittsburgh Sleep Quality Index >5 and sleep efficiency ≤85%) compared to OCD patients with good sleep quality (GSQ) and healthy controls (HCs), as well as the relationship of these indices to obsessive compulsive symptoms. Functional magnetic resonance spectroscopy (fMRS) was used to measure resting and active thalamic neurometabolite levels in 72 subjects (20 HCs and 38 OCD patients included in study analysis). Response inhibition function was measured by the Go-Nogo task before and during MRS recording. Subjective sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). The symptoms of OCD, anxiety and depression were evaluated using relevant clinical scales. OCD patients exhibited significantly reduced Glx/Cr levels in the resting thalamus. The levels of resting thalamic Glu/Cr and Glx/Cr in OCD patients with PSQ were significantly lowest. OCD patients had significantly lower correct rates on Go tasks, higher error rates on Nogo tasks, and longer error average response times (EART) to the Nogo task. OCD patients with PSQ demonstrated the highest Nogo task error rate and the longest EART to Nogo task. Furthermore, PSQI scores exhibited negative correlations with Glu/Cr and Glx/Cr in the resting thalamus. OCD patients with PSQ demonstrated reduced levels of thalamic resting Glx and more pronounced response inhibitory function impairment. Aberrant neurometabolite levels in critical brain regions, coupled with heightened response inhibition function deficits, may be a neurobiological basis for the PSQ that OCD patients generally exhibit. [ABSTRACT FROM AUTHOR]

Rapidly dissolving polymer thin films, or oral thin films (OTFs), have recently emerged as an improved oral drug delivery vehicle with its ability to bypass liver first pass metabolism, longer shelf-life, and simpler transport and distribution requirements, compared to traditional tablets and liquid formulations. Loratadine (LOR), an antihistamine commonly used to treat allergic rhinitis, undergoes liver first pass metabolism and is a prime candidate for incorporation within an OTF. However, loratadine is a BCS II drug with low aqueous solubility. Herein, the solubility of loratadine was improved by complexation with methyl β-cyclodextrin (MBCD) by co-evaporation of 2:1, 1:1, and 1:2 LOR:MBCD ratios and incorporation into a pullulan-based OTF at 4 wt% by solvent casting at 50 °C for 30 – 35 min. A therapeutically relevant 10 mg LOR dose could be prepared in a 3 cm by 3 cm OTF. The feasibility of complexation was observed with a B s -type phase solubility diagram, and complexation itself was confirmed via differential scanning calorimetry (DSC) by disappearance of the LOR melting peak, Fourier-transform infrared spectroscopy (FTIR) by shifting of the C=O peak, via 1H NMR spectroscopy by downfield shifting and change in peak multiplicity of the LOR aromatic protons, and via diffusion-ordered spectroscopy by a decrease in the diffusion coefficient of LOR:MBCD complex. LOR:MBCD could be incorporated homogeneously throughout an OTF, and LOR:MBCD OTFs exhibited reasonable mechanical strength and endured 12 ± 3 folds before breaking. LOR:MBCD OTFs disintegrated within 38 ± 10 s. The cumulative in vitro release of LOR:MBCD OTFs peaked at 80 % within 3–4 min of dissolution, and LOR in LOR:MBCD OTFs exhibited permeability across a 0.22 μm nitrocellulose membrane, demonstrating its applicability as a rapid drug delivery vehicle. [Display omitted] [ABSTRACT FROM AUTHOR]

Understanding environmental change is challenging and requires molecular‐level tools to explain the physicochemical phenomena behind complex processes. Nuclear magnetic resonance (NMR) spectroscopy is a key tool that provides information on both molecular structures and interactions but is underutilized in environmental research because standard "high‐field" NMR is financially and physically inaccessible for many and can be overwhelming to those outside of disciplines that routinely use NMR. "Low‐field" NMR is an accessible alternative but has reduced sensitivity and increased spectral overlap, which is especially problematic for natural, heterogeneous samples. Therefore, the goal of this study is to investigate and apply innovative experiments that could minimize these challenges and improve low‐field NMR analysis of environmental and biological samples. Spectral simplification (JRES, PSYCHE, singlet‐only, multiple quantum filters), selective detection (GEMSTONE, DREAMTIME), and heteronuclear (reverse and CH3/CH2/CH‐only HSQCs) NMR experiments are tested on samples of increasing complexity (amino acids, spruce resin, and intact water fleas) at‐high field (500 MHz) and at low‐field (80 MHz). A novel experiment called Doubly Selective HSQC is also introduced, wherein 1H signals are selectively detected based on the 1H and 13C chemical shifts of 1H–13C J‐coupled pairs. The most promising approaches identified are the selective techniques (namely for monitoring), and the reverse and CH3‐only HSQCs. Findings ultimately demonstrate that low‐field NMR holds great potential for biological and environmental research. The multitude of NMR experiments available makes NMR tailorable to nearly any research need, and low‐field NMR is therefore anticipated to become a valuable and widely used analytical tool moving forward. [ABSTRACT FROM AUTHOR]

Virus‐glycan interactions play a crucial role in the infection process of many viruses. NMR spectroscopy has emerged as a powerful tool for studying these interactions at the molecular level. In this article, we review several published papers and reports that have highlighted the application of NMR spectroscopy in understanding the complex questions of how viruses engage with and bind to receptor glycans. The use of saturation transfer difference (STD) NMR spectroscopy has demonstrated itself as highly advantageous in investigating the interaction between glycans and intact virions or virus‐like particles (VLPs). The broad NMR signal linewidth of virions and VLPs allows efficient saturation without affecting the glycan signals. The advantage of this approach is that the viral capsid environment in protein organization and function is not ignored and therefore provides a more biologically relevant model for exploring the interactions between the virus and the host cell glycans. We will review some examples of using NMR spectroscopy to study influenza cell tropism, rotaviruses, and noroviruses. [ABSTRACT FROM AUTHOR]

Efficient and robust analytical methods are needed to improve the identification and subsequent regulation of new psychoactive substances (NPS). NMR spectroscopy is a unique method able to determine the structure of small molecules such as NPS even in mixtures. However, high‐field NMR analysis is associated with expensive purchase and maintenance costs. For more than a decade, compact NMR spectrometers have changed this paradigm. It was recently shown that a dedicated analytical workflow combining compact NMR and databases could identify the molecular structure of NPS, in spite of the lower spectral dispersion and sensitivity of compact spectrometers. This approach relies on 1H‐13C HSQC to both recognize NPS and elucidate the structure of unknown substances. Still, its performance is limited by the need to compromise between resolution and experiment time. Here, we show that this strategy can be significantly improved by implementing non‐uniform sampling (NUS) to improve spectral resolution in the 13C dimension of HSQC at no cost in terms of experiment time. Gains in the range of 3 to 4 in resolution are achieved for pure NPS and for a mixture. Finally, 2D HSQC with NUS was applied to improve the identification of NPS with the assistance of databases. The resulting method appears as a useful tool for the characterization of NPS in mixtures, which is essential for forensic laboratories. [ABSTRACT FROM AUTHOR]

Benchtop NMR spectroscopy is attractive for process monitoring; however, there are still drawbacks that often hamper its use, namely, the comparatively low spectral resolution in 1H NMR, as well as the low signal intensities and problems with the premagnetization of flowing samples in 13C NMR. We show here that all these problems can be overcome by using 1H‐13C polarization transfer methods. Two ternary test mixtures (one with overlapping peaks in the 1H NMR spectrum and one with well‐separated peaks, which was used as a reference) were studied with a 1 T benchtop NMR spectrometer using the polarization transfer sequence PENDANT (polarization enhancement that is nurtured during attached nucleus testing). The mixtures were analyzed quantitatively in stationary as well as in flow experiments by PENDANT enhanced 13C NMR experiments, and the results were compared with those from the gravimetric sample preparation and from standard 1H and 13C NMR spectroscopy. Furthermore, as a proxy for a process monitoring application, continuous dilution experiments were carried out, and the composition of the mixture was monitored in a flow setup by 13C NMR benchtop spectroscopy with PENDANT. The results demonstrate the high potential of polarization transfer methods for applications in quantitative process analysis with benchtop NMR instruments, in particular with flowing samples. [ABSTRACT FROM AUTHOR]

Nuclear magnetic resonance (NMR) is an established method to determine self‐diffusion coefficients in liquids with high precision. The development of benchtop NMR spectrometers makes the method accessible to a wider community. In most cases, 1H NMR spectroscopy is used to determine self‐diffusion coefficients due to its high sensitivity. However, especially when using benchtop NMR spectrometers for the investigation of complex mixtures, the signals in 1H NMR spectra can overlap, hindering the precise determination of self‐diffusion coefficients. In 13C NMR spectroscopy, the signals of different compounds are generally well resolved. However, the sensitivity of 13C NMR is significantly lower than that of 1H NMR spectroscopy leading to very long measurement times, which makes diffusion coefficient measurements based on 13C NMR practically infeasible with benchtop NMR spectrometers. To circumvent this problem, we have combined two known pulse sequences, one for polarization transfer from 1H to the 13C nuclei (PENDANT) and one for the measurement of diffusion coefficients (PFG). The new method (PENPFG) was used to measure the self‐diffusion coefficients of three pure solvents (acetonitrile, ethanol and 1‐propanol) as well as in all their binary mixtures and the ternary mixture at various compositions. For comparison, also measurements of the same systems were carried out with a standard PFG‐NMR routine on a high‐field NMR instrument. The results are in good agreement and show that PENPFG is a useful tool for the measurement of the absolute value of the self‐diffusion coefficients in complex liquid mixtures with benchtop NMR spectrometers. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to prepare a new donor–π–acceptor (D–π–A) and acceptor–π– D–π–A (A–π–D–π–A) phenothiazine (PTZ) in conjugation with vinyl isophorone (PTZ-1 and PTZ-2) were designed and their molecular shape, electrical structures and characteristics have been explored using the density functional theory (DFT). The results satisfactorily explain that the higher conjugative effect resulted in a smaller high occupied molecular orbital–lowest unoccupied molecular orbital gap (Eg). Both compounds show intramolecular charge transfer (ICT) transitions in the ultraviolet (UV)–visible range, with a bathochromic shift and higher absorption oscillator strength, as determined by DFT calculations. Design/methodology/approach: The produced PTZ-1 and PTZ-2 sensors were characterized using various spectroscopic methods, including Fourier-transform infrared spectroscopy and nuclear magnetic resonance spectroscopy (1H/13CNMR). UV–visible absorbance spectra of the generated D–π–A PTZ-1 and A–π–D–π–A PTZ-2 dyes were explored in different solvents of changeable polarities to illustrate positive solvatochromism correlated to intramolecular charge transfer. Findings: The emission spectra of PTZ-1 and PTZ-2 showed strong solvent-dependent band intensity and wavelength. Stokes shifts were monitored to increase with the increase of the solvent polarity up to 4122 cm−1 for the most polar solvent. Linear energy-solvation relationship was applied to inspect solvent-dependent Stokes shifting. Quantum yield (ф) of PTZ-1 and PTZ-2 was also explored. The maximum UV–visible absorbance wavelengths were detected at 417 and 419 nm, whereas the fluorescence intensity was monitored at 586 and 588 nm. Originality/value: The PTZ-1 and PTZ-2 dyes leading to colorimetric and emission spectral changes together with a color shift from yellow to red. [ABSTRACT FROM AUTHOR]

Smart materials represent an emerging and highly exploited category, particularly in the creation of textiles that can sense and respond to various external stimuli, such as temperature or humidity. This study introduces for the first time the hygroscopic elongation and drying shrinkage properties of stimulus-responsive single-component polyamide (PA) fibers copolymerized with polyetherdiamine and diethylenetriamine (DETA). PA copolymers containing 5-15% polyetherdiamine were comprehensively characterized, including nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FT-IR), relative viscosity, and differential scanning calorimetry (DSC) analyses. Subsequently, these PA copolymers were successfully melt-spun into fibers and knitted into double-layered fabrics. PA fibers containing 15% polyetherdiamine showed significant results, with a moisture-absorbing elongation of 15.6% and a drying shrinkage of 94.9%. The Qmax and moisture regain of the PA fabric are 0.206 W·cm-2 and 4.4%, respectively. These moisture-driven, fiber-based smart textiles exhibit changes in breathability and shape retention at different humidity levels, thereby maintaining a more comfortable microclimate. Such textiles have great potential for widespread use in clothing, helping to improve comfort and adaptability. [ABSTRACT FROM AUTHOR]

Background: Glucocorticoids and sclerostin act as inhibitors of the Wnt signaling pathway, thereby hindering bone formation. Given the pathway's intricate association with mesenchymal stem cells, the hypothesis suggests that heightened sclerostin levels may be intricately linked to an augmentation in marrow adiposity induced by glucocorticoids. This study endeavored to delve into the nuanced relationship between circulating sclerostin and bone marrow adipose tissue in postmenopausal women grappling with glucocorticoid-induced osteoporosis (GIO). Methods: In this cross-sectional study, 103 patients with autoimmune-associated diseases underwent glucocorticoid treatment, boasting an average age of 61.3 years (standard deviation 7.1 years). The investigation encompassed a thorough assessment, incorporating medical history, anthropometric data, biochemical analysis, and dual-energy X-ray absorptiometry measurements of lumbar and femoral bone mineral density (BMD). Osteoporosis criteria were established at a T-score of -2.5 or lower. Additionally, MR spectroscopy quantified the vertebral marrow fat fraction. Results: BMD at the femoral neck, total hip, and lumbar spine showcased an inverse correlation with marrow fat fraction (r = –0.511 to – 0.647, P < 0.001). Serum sclerostin levels exhibited a positive correlation with BMD at various skeletal sites (r = 0.476 to 0.589, P < 0.001). A noteworthy correlation emerged between circulating sclerostin and marrow fat fraction at the lumbar spine (r = –0.731, 95% CI, –0.810 to –0.627, P < 0.001). Multivariate analysis brought to light that vertebral marrow fat fraction significantly contributed to sclerostin serum concentrations (standardized regression coefficient ß = 0.462, P < 0.001). Even after adjusting for age, body mass index, physical activity, renal function, BMD, and the duration and doses of glucocorticoid treatment, serum sclerostin levels maintained a significant correlation with marrow fat fraction. Conclusions: Circulating sclerostin levels exhibited a noteworthy association with marrow adiposity in postmenopausal women grappling with GIO. [ABSTRACT FROM AUTHOR]

The attempted synthesis of [{Carb}BaPPh2] (1) showed this barium-phosphide and its thf adducts, 1·thf and 1·(thf)2, to be unstable in solution. Our strategy to circumvent the fragility of these compounds involved the use of phosphinoboranes HPPh2·BH3 and HPPh2·B(C6F5)3 instead of HPPh2. This allowed for the synthesis of [{Carb}Ae{PPh2·BH3}] (Ae = Ba, 2; Ca, 3), [{Carb}Ca{(H3B)2PPh2}·(thf)] (4), [{Carb}Ba{PPh2·B(C6F5)3}] (5), [{Carb}Ba{O(B(C6F5)3)CH2CH2CH2CH2PPh2}·thf] (6), [Ba{O(B(C6F5)3)CH2CH2CH2CH2PPh2}2·(thf)1.5] (7) and [Ba{PPh2·B(C6F5)3}2·(thp)2] (8) that were characterised by multinuclear NMR spectroscopy (thp = tetrahydropyran). The molecular structures of 4, 6 and 8 were validated by X-ray diffraction crystallography, which revealed the presence of Ba⋯F stabilizing interactions (ca. 9 kcal mol−1) in the fluorine-containing compounds. Compounds 6 and 7 were obtained upon ring-opening of thf by their respective precursors, 5 and the in situ prepared [Ba{PPh2·B(C6F5)3}2]n. By contrast, thp does not undergo ring-opening under the same conditions but affords clean formation of 8. DFT analysis did not highlight any specific weakness of the Ba–P bond in 1·(thf)2. The instability of this compound is instead thought to stem from the high energy of its HOMO, which contains the non-conjugated P lone pair and features significant nucleophilic reactivity. [ABSTRACT FROM AUTHOR]

One or two phenylacetylide (PA) ligand(s) were successfully removed from the IrAu12 superatomic core of [IrAu12(dppe)5(PA)2]+ (dppe=1,2‐bis(diphenylphosphino)ethane) by reaction with controlled amounts of tetrafluoroboric acid. Optical and nuclear magnetic resonance spectroscopies and density functional theory calculations revealed the formation of open Au site(s) on the IrAu12 core of [IrAu12(dppe)5(PA)1]2+ and [IrAu12(dppe)5]3+ with the remaining structure intact. Isocyanide was efficiently trapped at the open electrophilic site on [IrAu12(dppe)5(PA)1]2+, whereas a dimer or trimer of the IrAu12 superatoms was formed using diisocyanide as a linker. These results open the door to designed assembly of chemically modified metal superatoms. [ABSTRACT FROM AUTHOR]

Cytisine (CTS) is a useful medicine for treating nervous disorders and smoking addiction, and exploring a convenient method to detect CTS is of great significance for long‐term/home medication to avoid the risk of poisoning, but it is full of challenges. Here, a modified metal–organic framework sensor Tb@Zn‐TDA‐80 with dual emission centers was prepared using a post‐modified luminescence center strategy. The obtained Tb@Zn‐TDA‐80 can serve as a CTS sensor with high sensitivity and selectivity. To achieve portable detection, Tb@Zn‐TDA‐80 was further fabricated as a membrane sensor, M−Tb@Zn‐TDA‐80, which displayed an obvious CTS‐responsive color change by simply dropping a CTS solution onto its surface. Benefiting from this unique functionality, M−Tb@Zn‐TDA‐80 successfully realized the visual detection and quantitative monitoring of CTS in the range of 5.26–52.6 mM by simply scanning the color with a smartphone. The results of nuclear magnetic resonance spectroscopy and theoretical computation illustrated that the high sensing efficiency of Tb@Zn‐TDA‐80 for CTS was attributed to the N−H⋅⋅⋅π and π⋅⋅⋅π interactions between the ligand and CTS. And luminescence quenching may result from the intramolecular charge transfer. This study provides a convenient method for ensuring long‐term medication safety at home. [ABSTRACT FROM AUTHOR]

A series of terminal mono‐ and disubstituted beryllium azides of the form [(CAAC)Be(N3)R] (R=CAACH, Dur; CAACH/CAAC=1‐(2,6‐diisopropylphenyl)‐3,3,5,5‐tetramethylpyrrolidin‐2‐yl/idene, Dur=2,3,5,6‐tetramethylphenyl) and [L2Be(N3)2] (L=CAACNH=1‐(2,6‐diisopropylphenyl)‐3,3,5,5‐tetramethylpyrrolidin‐2‐imine, IiPrMe=1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene), respectively, were synthesized and characterized by NMR spectroscopy and X‐ray crystallography. Thermolysis and photolysis products of these first examples of tricoordinate azidoberyllium complexes evidence extensive ligand scrambling and the formal insertion of nitrenes into the CAAC−Be bond, generating cyclic alkyl(amino)imine (CAAI) ligands. Furthermore, the reaction with a small N‐heterocyclic carbene (NHC) leads to unexpected CAAC‐NHC ligand exchange, while the reaction with pentaphenylborole yields the first γ‐azide adduct of a borole, long postulated to be the first step in the synthesis of 1,2‐azaborinines from boroles and azides. [ABSTRACT FROM AUTHOR]

The investigation of reaction mechanisms is a complex task that usually requires the use of several techniques. To obtain as much information as possible on the reaction and any intermediates – possibly invisible to one technique – the combination of techniques is a solution. In this work we present a new setup for combined UV/Vis and NMR spectroscopy and compare it to an established alternative. The presented approach allows a versatile usage of different commercially‐available components like mirrors and fiber bundles as well as different fixed pathlengths according to double transmission or single transmission measurements. While a previous approach is based on a dip‐probe setup for conventional NMR probes, the new one is based on a micro‐Helmholtz coil array (LiquidVoxel™). This makes the use of rectangular cuvettes possible, which ensure well‐defined pathlengths allowing for quantification of species. Additionally, very low quantities of compound can be analyzed due to the microfabrication and small cuvette size used. As proof‐of‐principle this new setup for combined UV/Vis and NMR spectroscopy is used to examine a well‐studied photochromic system of the dithienylethene compound class. A thorough comparison of the pros and cons of the two setups for combined UV/Vis and NMR measurements is performed. [ABSTRACT FROM AUTHOR]

Lewis superacids (LSA) are defined by a fluoride ion affinity (FIA) that exceeds that of SbF5, and are thus characterized as hard according to the HSAB concept. Soft superacidity was defined for compounds exceeding the hydride ion affinity (HIA) of B(C6F5)3. Herein we report on the synthesis of a Lewis acid being superacidic only on the soft regime: tris(pentafluoroethyl)indane, In(C2F5)3. It is accessible in the form of its dihydrate [In(C2F5)3(OH2)2]. An improved synthesis for the gallium analogue [Ga(C2F5)3(OH2)2] is also reported. Tris(pentafluoroethyl)indane dihydrate, [In(C2F5)3(OH2)2], was fully characterized by IR and NMR spectroscopy, as well as by single crystal X‐ray diffraction. Due to their stability and convenient accessibility, the hydrates are ideal starting compounds for the chemistry of tris(pentafluoroethyl)gallium and ‐indium compounds, for example hydroxogallates and ‐indates. An attempt to determine its gas‐phase structure and that of the gallium analogue by electron diffraction demonstrates that they lose water ligands upon evaporation. The energetics of these processes were predicted by quantum‐chemical calculations as was the nature of bonding in the free Lewis acids and their mono‐ and dihydrates. Furthermore, the synthesis and structural diversity of hydroxido tris(pentafluoroethyl) gallates and one indate are presented. [ABSTRACT FROM AUTHOR]