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The naturally occurring 3″- O -acylquercitrin family exhibits a range of biological activities with significant potential health and medical benefits. Herein, we present a unified strategy for concise total syntheses of all six known 3″- O -acylquercitrin natural products─namely, 3″- O -galloylquercitrin, 3″- O -( E )-cinnamoylquercitrin, 3″- O -( E )-coumaroylquercitrin, 3″- O -( E )-feruloylquercitrin, 3″- O -acetylquercitrin, and 3″- O -tigloylquercitrin─based on regioselective acylation of carbohydrates catalyzed by N -methylimidazole-containing boronic acid. The core advancement in this approach is a late-stage catalytic regioselective functionalization of a common synthetic intermediate, enabling efficient access to the natural products.

The title compound was synthesized, and ESR and magnetic analysis revealed diamagnetic properties below 400 K. The crystal structure analysis clarified that the molecule possesses an approximate C 2 symmetry with a head-to-tail (N-O) 2 four-membered ring. The N···O distances are 2.349(4) - 2.374(4) Å, belonging to the class found in diamagnetic phases of dimerized nitroxide materials. A zero-field splitting pattern appeared in the solid-state ESR around 440 K on heating. The density functional theory (DFT) calculations supported the formation of a biradical.

Although the reverse nonequilibrium molecular dynamics (RNEMD) simulation method has been widely employed, the range of applicability is yet to be discussed. In this study, for the first time, we systematically examine the method against an unentangled melt of the Kremer-Grest type chain. The simulation results indicate that as the shear rate increases, the temperature and density become inhomogeneous. However, the average viscosity remains consistent with the results obtained using the SLLOD method under homogeneous temperature and density. We also confirm that the temperature-density inhomogeneity does not significantly affect polymer conformation.

Crystalline silicotitanate (CST) with a sitinakite structure has attracted considerable attention as an ion exchanger because of its anionic surface owing to SiO 4 tetrahedral and TiO 6 octahedral linked structures. In particular, the anionic surface of CST is advantageous in immobilizing single Au atoms derived from a cationic precursor such as Au(en) 2 Cl 3 (en = ethylenediamine). In this study, a Au/CST catalyst was prepared and evaluated for CO oxidation. The transmission electron microscopy and X-ray photoelectron spectroscopy results suggest that Au single atoms and clusters (Au δ+ , 0 < δ < 1) were supported on Na + -CST particles. The 1.0 wt % Au/CST catalyst yielded high catalytic activity for CO oxidation, where 50% CO oxidation was achieved at a low temperature of -13 °C. In the low-temperature region (from -84 to 20 °C), CO oxidation over Au/CST may progress through the well-known Langmuir-Hinshelwood mechanism. Conversely, the experimental results of CO oxidation without O 2 confirmed that the reaction proceeded according to the Au-assisted Mars-van Krevelen mechanism using the lattice oxygens of the CST particles at temperatures above 20 °C. Therefore, this work contributes to the design of highly dispersed single-atom or cluster catalysts using the anionic surface of the microporous CST., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Nanostructured lead telluride PbTe is among the best-performing thermoelectric materials, for both p- and n-types, for intermediate temperature applications. However, the fabrication of power-generating modules based on nanostructured PbTe still faces challenges related to the stability of the materials, especially nanoprecipitates, and the bonding of electric contacts. In this study, in situ high-temperature transmission electron microscopy observation confirmed the stability of nanoprecipitates in p-type Pb 0.973 Na 0.02 Ge 0.007 Te up to at least ∼786 K. Then, a new architecture for a packaged module was developed for improving durability, preventing unwanted interaction between thermoelectric materials and electrodes, and for reducing thermal stress-induced crack formation. Finite element method simulations of thermal stresses and power generation characteristics were utilized to optimize the new module architecture. Legs of nanostructured p-type Pb 0.973 Na 0.02 Ge 0.007 Te (maximum zT ∼ 2.2 at 795 K) and nanostructured n-type Pb 0.98 Ga 0.02 Te (maximum zT ∼ 1.5 at 748 K) were stacked with flexible Fe-foil diffusion barrier layers and Ag-foil-interconnecting electrodes forming stable interfaces between electrodes and PbTe in the packaged module. For the bare module, a maximum conversion efficiency of ∼6.8% was obtained for a temperature difference of ∼480 K. Only ∼3% reduction in output power and efficiency was found after long-term operation of the bare module for ∼740 h (∼31 days) at a hot-side temperature of ∼673 K, demonstrating good long-term stability.

Facilitating the selective electrochemical oxidation of methanol into value-added formate is essential for electrochemical refining. Here we propose a high-dimensional Nb 2 O 5 on Ni foam (Nb 2 O 5 -HD@NF) composite as anode for methanol oxidation reaction (MOR) for efficient production of formate. In an electrolyte containing 3 M methanol aqueous solution, the Nb 2 O 5 -HD@NF anode requires only 240 mV overpotential to deliver an industrial-level current density of 100 mA cm -2 with a formate Faraday efficiency of 100%. In situ Raman and electrochemical kinetic analyses reveal that the origin of the excellent activity in 3 M methanol electrolyte can be ascribed to the NbO 6 octahedra as active sites and the Lewis acid sites on the surface of Nb 2 O 5 -HD. This work may pave a way for the design of non-noble metal electrocatalysts with surface acidity engineering for the effective electrocatalytic upgrading of biomass molecules.

In this study, we investigated the water concentration dependence of the intermolecular vibrations of two hydrated ionic liquids (ILs), cholinium dihydrogen phosphate ([ch][dhp]) and cholinium bromide ([ch]Br), using femtosecond Raman-induced Kerr effect spectroscopy (fs-RIKES). The anions of the former and latter hydrated ILs are kosmotropic and chaotropic, respectively. We found that the spectral peak of ∼50 cm -1 shifted to the low-frequency side in hydrated [ch][dhp], indicating the weakening of its intermolecular interactions. In contrast, no change in the peak frequency of the low-frequency band at ∼50 cm -1 was observed with increasing water concentration in hydrated [ch]Br. The vibrational density of states (VDOS) spectra generated from molecular dynamics (MD) simulations were in qualitative agreement with the experimental results. Decomposition analysis of the VDOS spectra for each component revealed that the red shift of the low-frequency band in the hydrated [ch][dhp] upon water addition was essentially due to the contributions of anions and water rather than that of the cholinium cation. We also found from the low-frequency spectra of the two hydrated ILs that they differed in the concentration dependence of the 180 cm -1 band, which is assigned as a hindered translational motion of water molecules combined to form O···O stretching motions. From the relationship between the peak frequency of the low-frequency band and the bulk parameter, which is the square root of the surface tension divided by the density, we found that the peak frequency in the hydrated IL with kosmotropic [dhp] - depends on the bulk parameter, similar to the case for an aqueous solution of the typical deep eutectic solvent reline. However, the peak frequency of the hydrated IL with chaotropic Br - is constant with the bulk parameter.

The catalytic performance of supported metal catalysts is closely related to their structure. While Pt-based catalysts are widely used in many catalytic reactions because of their exceptional intrinsic activity, they tend to deactivate in high-temperature reactions, requiring a tedious and expensive regeneration process. The strong metal-support interaction (SMSI) is a promising strategy to improve the stability of supported metal nanoparticles, but often at the price of the activity due to either the coverage of the active sites by support overlay and/or the too-strong metal-support bonding. Herein, we newly constructed a supported Pt cluster catalyst by introducing FeO x into hydroxyapatite (HAP) support to fine-tune the SMSIs. The catalyst exhibited not only high catalytic activity but also sintering resistance, without deactivation in a 100 h test for catalytic CO oxidation. Detailed characterizations reveal that FeO x introduced into HAP weaken the strong covalent metal-support interaction (CMSI) between Pt and FeO x while simultaneously inhibiting the oxidative strong metal-support interaction (OMSI) between Pt and HAP, giving rise to both high activity and thermal stability of the supported Pt clusters.

Supported particulate noble-metal catalysts are widely used in industrial catalytic reactions. However, these metal species, whether in the form of nanoparticles or highly dispersed entities, tend to aggregate during reactions, leading to a reduced activity or selectivity. Addressing the frequent necessity for the replacement of industrial catalysts remains a significant challenge. Herein, we demonstrate the feasibility of the 'regenerable catalytic system' exemplified by selective catalytic oxidation of ammonia (NH 3 -SCO) employing Ag/Al 2 O 3 catalysts. Results demonstrate that our highly dispersed Ag catalyst (Ag HD) maintains >90% N 2 selectivity at 80% NH 3 conversion and >80% N 2 selectivity at 100% NH 3 conversion after enduring 5 cycles of reducible aggregation and oxidative dispersion. Moreover, it consistently upholds over 98% N 2 selectivity at 100% NH 3 conversion after 10 cycles of Ar treatment. During the aggregation-dispersion process, the Ag HD catalyst intentionally aggregated into Ag nanoparticles (Ag NP) after H 2 reduction and exhibited remarkable regenerable capabilities, returning to the Ag HD state after calcination in the air. This structural evolution was characterized through in situ transmission electron microscopy, atomically resolved high-angle annular dark-field scanning transmission electron microscopy, and X-ray absorption spectroscopy, revealing the on-site oxidative dispersion of Ag NP. Additionally, in situ diffuse reflectance infrared Fourier transform spectroscopy provided insights into the exceptional N 2 selectivity on Ag HD catalysts, elucidating the critical role of NO + intermediates. Our findings suggest a sustainable and cost-effective solution for various industry applications.

E7130 is a novel drug candidate with an exceedingly complex chemical structure of the halichondrin class, discovered by a total synthesis approach through joint research between the Kishi group at Harvard University and Eisai. Only 18 months after completion of the initial milligram-scale synthesis, ten-gram-scale synthesis of E7130 was achieved, providing the first good manufacturing practice (GMP) batch to supply clinical trials. This paper highlights the challenges in developing ten-gram-scale synthesis from the milligram-scale synthesis.

Long-term phosphorus (P) fertilization results in P accumulation in agricultural soil and increases the risk of P leaching into water bodies. However, evaluating P leaching into groundwater is challenging, especially in clay soil with a high P sorption capacity. This study examined whether the combination of PO 4 oxygen isotope (δ 18 O PO4 ) analysis and the P saturation ratio (PSR) was useful to identify P enrichment mechanisms in groundwater. We investigated the groundwater and possible P sources in Kubi, western Japan, with intensive citrus cultivation. Shallow groundwater had oxic conditions with high PO 4 concentrations, and orchard soil P accumulation was high compared with forest soil. Although the soil had a high P sorption capacity, the PSR was above the threshold, indicating a high risk of P leaching from the surface orchard soil. The shallow groundwater δ 18 O PO4 values were higher than the expected isotopic equilibrium with pyrophosphatase. The high PSR and δ 18 O PO4 orchard soil values indicated that P leaching from orchard soil was the major P enrichment mechanism. The Bayesian mixing model estimated that 76.6% of the P supplied from the orchard soil was recycled by microorganisms. This demonstrates the utility of δ 18 O PO4 and the PSR to evaluate the P source and biological recycling in groundwater.

In thermoelectric and other inorganic materials research, the significance of half-Heusler (HH) compositions following the 18-electron rule has drawn interest in developing and exploiting the potential of intermetallic compounds. For the fabrication of thermoelectric modules, in addition to high-performance materials, having both p- and n-type materials with compatible thermal expansion coefficients is a prerequisite for module development. In this work, the p-type to n-type transition of valence balanced/unbalanced HH composition of Mg 1- x V x NiSb was demonstrated by changing the Mg:V chemical ratio. The Seebeck coefficient and power factor of Ti-doped Mg 0.57 V 0.33 Ti 0.1 NiSb are -130 μV K -1 and 0.4 mW m -1 K -2 at 400 K, respectively. In addition, the reduced lattice thermal conductivity (κ L < 2.5 W m -1 K -1 at 300 K) of n-type compositions was reported to be much smaller than κ L of conventional HH materials. As high thermal conductivity has long been an issue for HH materials, the synthesis of p- and n-type Mg 1- x V x NiSb compositions with low lattice thermal conductivity is a promising strategy for producing high-performance HH compounds. Achieving both p- and n-type materials from similar parent composition enabled us to fabricate a thermoelectric module with maximum output power P max ∼ 63 mW with a temperature difference of 390 K. This finding supports the benefit of exploring the huge compositional space of valence balanced/unbalanced quaternary HH compositions for further development of thermoelectric devices.

In an attempt to generalize "on surface synthesis", which has unique potential in the area of organic synthesis, the focus was placed on layered silicates having a highly flat surface. The photoreaction of (±)-13-bromo-6a-azonia[5]helicene (AHHBr) and (±)-2-bromo-13-methyl-6a-azonia[5]helicene (AHBrMe) in solution and within the layers was examined. In the case of AHBrMe, the photoproduct was different from that in solution. 1 H nuclear magnetic resonance (NMR), Fourier transform-infrared spectroscopy (FT-IR), and electrospray ionization-mass spectrometry (ESI-MS) measurements revealed that the photoproduct obtained within the layers was a benzo-perylene molecule with a completely flat lactone structure (AL). This study is the first example of the successful conversion of a chemical reaction path due to the steric effect of the flat surface of layered silicate.

Poly(ethylene glycol) (PEG) is used in many common products, such as cosmetics. PEG, however, is also used to covalently conjugate drug molecules, proteins, or nanocarriers, which is termed PEGylation, to serve as a shield against the natural immune system of the human body. Repeated administration of some PEGylated products, however, is known to induce anti-PEG antibodies. In addition, preexisting anti-PEG antibodies are now being detected in healthy individuals who have never received PEGylated therapeutics. Both treatment-induced and preexisting anti-PEG antibodies alter the pharmacokinetic properties, which can result in a subsequent reduction in the therapeutic efficacy of administered PEGylated therapeutics through the so-called accelerated blood clearance (ABC) phenomenon. Moreover, these anti-PEG antibodies are widely reported to be related to severe hypersensitivity reactions following the administration of PEGylated therapeutics, including COVID-19 vaccines. We recently reported that the topical application of a cosmetic product containing PEG derivatives induced anti-PEG immunoglobulin M (IgM) in a mouse model. Our finding indicates that the PEG derivatives in cosmetic products could be a major cause of the preexistence of anti-PEG antibodies in healthy individuals. In this study, therefore, the pharmacokinetics and therapeutic effects of Doxil (doxorubicin hydrochloride-loaded PEGylated liposomes) and oxaliplatin-loaded PEGylated liposomes (Liposomal l-OHP) were studied in mice. The anti-PEG IgM antibodies induced by the topical application of cosmetic products obviously accelerated the blood clearance of both PEGylated liposomal formulations. Moreover, in C26 tumor-bearing mice, the tumor growth suppressive effects of both Doxil and Liposomal l-OHP were significantly attenuated in the presence of anti-PEG IgM antibodies induced by the topical application of cosmetic products. These results confirm that the topical application of a cosmetic product containing PEG derivatives could produce preexisting anti-PEG antibodies that then affect the therapeutic efficacy of subsequent doses of PEGylated therapeutics.

Exfoliated M-Al layered double hydroxide (M-Al LDH; M = Mg, Co, Ni, and Zn) nanosheets were adsorbed on Au/SiO 2 and calcined to transform LDH into mixed metal oxides (MMOs) and yield Au/SiO 2 coated with a thin MMO overlayer. These catalysts showed a higher catalytic activity than pristine Au/SiO 2 . In particular, the 50% CO conversion temperature decreased by more than 250 °C for Co-Al MMO-coated Au/SiO 2 . In contrast, the deposition of CoAlO x on Au/SiO 2 by impregnation or the deposition of Au on Co-Al MMO-coated SiO 2 resulted in a worse catalytic activity. Moreover, the presence of a thick MMO overlayer decreased the catalytic activity, suggesting that the control of the overlayer thickness to less than 1 nm is a requisite for obtaining a high catalytic activity. Moreover, the thin Co-Al MMO overlayer on Au/SiO 2 possessed abundant oxygen vacancies, which would play an important role in O 2 activation, resulting in a highly active interface between Au and the defect-rich MMO on the Au NP surface. Finally, this can be applied to Pt/SiO 2 , and the obtained Co-Al MMO-coated Pt/SiO 2 also exhibited a much improved catalytic activity for CO oxidation.

The safety and efficacy of hemoglobin vesicles (HbVs) as artificial oxygen carriers encapsulating a purified and concentrated Hb solution in liposomes have been studied extensively. The HbV surface, modified with PEG by incorporating a PEG-conjugated phospholipid, is beneficial for storage and biocompatibility. However, it might be possible that interaction of PEG and the pre-existing anti-PEG antibody in the bloodstream causes acute adverse reaction. This study used two sets of experiments with rats and guinea pigs to ascertain whether the anti-PEG antibody generated by the PEG-modified HbV injection can induce anaphylactic reactions. SD rats received repeated intravenous injection of HbV at a dose rate of 16 or 32 mL/kg three times. Not anti-PEG IgG but anti-PEG IgM was detected. Nevertheless, no anaphylactic reaction occurred. Guinea pigs were used to study the presence of active systemic anaphylaxis further after injections of the PEG-modified liposomes used for HbV. The animals were sensitized by three repeated subcutaneous injections of PEG-modified liposomes (PEG-liposome) along with adjuvant at 1 week intervals. For comparison, unmodified liposomes (liposome) and 10 times excessively PEG-modified liposomes with ionizable lipid (10PEG-DODAP-liposome) were used. Inclusion of PEG modification induced not only anti-PEG IgM but also anti-PEG IgG. Three weeks after the final injection, intravenous injection of both PEG-liposome and liposome (1 mL/kg) induced no anaphylactic reaction. However, the injection of 10PEG-DODAP-liposome showed one lethal anaphylaxis case and one mild anaphylaxis case. Antisera obtained from the animal sensitized as described above were inoculated (0.05 mL) intradermally into fresh guinea pigs. The presence of passive cutaneous anaphylaxis was evaluated after intravenous injections (1 mL/kg) of three liposomes with Evans blue. No dye leakage was detected at any inoculated skin point for PEG-liposome or liposome, but a slight leakage was detected in one inoculated skin point for 10PEG-DODAP-liposome. These results indicate the absence of acute allergic reactions at repeated injections of HbVs despite the anti-PEG antibody induction. Not all the PEG-modified liposomes show anaphylaxis, and it may depend on the amount of PEGylated phospholipid and lipid composition of PEG-modified liposomes., Competing Interests: The authors declare the following competing financial interest(s): Of the authors, H.S. is an inventor of patents related to the production and utilization of Hb vesicles., (© 2023 The Authors. Published by American Chemical Society.)

Accurate prediction of protein stability upon a point mutation has important applications in drug discovery and personalized medicine. It remains a challenging issue in computational biology. Existing computational prediction methods, which range from mechanistic to supervised learning approaches, have experienced limited progress over the last few decades. This stagnation is largely due to their heavy reliance on both the quantity and quality of the training data. This is evident in recent state-of-the-art methods that continue to yield substantial errors on two challenging blind test sets: frataxin and p53, with average root-mean-square errors exceeding 3 and 1.5 kcal/mol, respectively, which is still above the theoretical 1 kcal/mol prediction barrier. Rigorous approaches, on the other hand, offer greater potential for accuracy without relying on training data but are computationally demanding and require both wild-type and mutant structure information. Although they showed high accuracy for conserving mutations, their performance is still limited for charge-changing mutation cases. This might be due to the lack of an available mutant structure, often represented by a simplified capped peptide. The recent advances in protein structure prediction methods now make it possible to obtain structures comparable to experimental ones, including complete mutant structure information. In this work, we compare the performance of supervised learning-based methods and rigorous approaches for predicting protein stability on point mutations in difficult targets: frataxin and p53. The rigorous alchemical method significantly surpasses state-of-the-art techniques in terms of both the root-mean-squared error and Pearson correlation coefficient in these two challenging blind test sets. Additionally, we propose an improved alchemical method that employs the pmx double-system/single-box approach to accurately predict the folding free energy change upon both conserving and charge-changing mutations. The enhanced protocol can accurately predict both types of mutations, thereby outperforming existing state-of-the-art methods in overall performance.

Hepatitis is an inflammation of the liver caused by the inadequate elimination of reactive oxygen species (ROS) derived from Kupffer cells. Edaravone is clinically used as an antioxidant but shows poor liver distribution. Herein, we report on the design of a Kupffer cell-oriented nanoantioxidant based on a disulfide cross-linked albumin nanoparticle containing encapsulated edaravone (EeNA) as a therapeutic for the treatment of hepatitis. Since the edaravone is bound to albumin, this results in a soluble and stable form of edaravone in water. Exchanging the intramolecular disulfide bonds to intermolecular disulfide bridges of albumin molecules allowed the preparation of a redox responsive albumin nanoparticle that is stable in the blood circulation but can release drugs into cells. Consequently, EeNA was fabricated by the nanoscale self-assembly of edaravone and albumin nanoparticles without the additives that are contained in commercially available edaravone preparations. EeNA retained its nanostructure under serum conditions, but the encapsulated edaravone was released efficiently under intracellular reducing conditions in macrophages. The EeNA was largely distributed in the liver and subsequently internalized into Kupffer cells within 60 min after injection in a concanavalin-A-induced hepatitis mouse. The survival rate of the hepatitis mice was significantly improved by EeNA due to the suppression of liver necrosis and oxidative stress by scavenging excessive ROS. Moreover, even through the postadministration, EeNA showed an excellent hepatoprotective action as well. In conclusion, EeNA has the potential for use as a nanotherapeutic against various types of hepatitis because of its Kupffer cell targeting ability and redox characteristics.

Au nanoparticles are efficient catalysts for selective oxidations. The interaction between Au nanoparticles and supports is critical for achieving high catalytic activity. Herein, Au nanoparticles are supported on a zeolitic octahedral metal oxide based on Mo and V. The charge of Au is controlled by the surface oxygen vacancies of the supports, and the redox property of the zeolitic vanadomolybdate is highly dependent on Au loading. The Au-supported zeolitic vanadomolybdate is used as a heterogeneous catalyst for alcohol oxidation under mild conditions with molecular oxygen as an oxidant. The supported Au catalyst can be recovered and reused without the loss of activity.

Gold nanoparticles (Au NPs) deposited on various cation- and anion-substituted hydroxyapatites (Au/sHAPs) show oxidative strong metal-support interaction (SMSI), wherein a thin layer of the sHAP covered the surface of the Au NPs by heat treatment in an oxidative atmosphere. Calcination of Au/sHAPs at 300 °C caused a partial SMSI and that at 500 °C gave fully encapsulated Au NPs. We investigated the influence of the substituted ions in sHAP and the degree of the oxidative SMSI on the catalytic performance of Au/sHAPs for oxidative esterification of octanal or 1-octanol with ethanol to obtain ethyl octanoate. The catalytic activity depends on the size of the Au NPs but not on the support used, owing to the similarity of the acid and base properties of sHAPs except for Au/CaFAP. The presence of a large number of acidic sites on CaFAP lowered the product selectivity, but all other sHAPs exhibited similar activity when the Au particle size was almost the same, owing to the similarity of the acid and base properties. Au/sHAPs&#95;O 2 with SMSI exhibited higher catalytic activity than Au/sHAPs&#95;H 2 without SMSI despite the fact that the number of exposed surface Au atoms was decreased by the SMSI. In addition, the oxidative esterification reaction proceeded even though the Au NPs were fully covered by the sHAP layer when the thickness of the layer was controlled to be less than 1 nm. The substrate can access the surfaces of the Au NPs covered by the thin sHAP layer (<1 nm), and the presence of the sHAP structure in close contact with the Au NPs resulted in significantly higher catalytic activity compared with that for fully exposed Au NPs deposited on the sHAPs. This result suggests that maximizing the contact area between the Au NPs and the sHAP support based on the SMSI enhances the catalytic activity of Au.

In drug discovery research, the selection of promising binding sites and understanding the binding mode of compounds are crucial fundamental studies. The current understanding of the proteins-ligand binding model extends beyond the simple lock and key model to include the induced-fit model, which alters the conformation to match the shape of the ligand, and the pre-existing equilibrium model, selectively binding structures with high binding affinity from a diverse ensemble of proteins. Although methods for detecting target protein binding sites and virtual screening techniques using docking simulation are well-established, with numerous studies reported, they only consider a very limited number of structures in the diverse ensemble of proteins, as these methods are applied to a single structure. Molecular dynamics (MD) simulation is a method for predicting protein dynamics and can detect potential ensembles of protein binding sites and hidden sites unobservable in a single-point structure. In this study, to demonstrate the utility of virtual screening with protein dynamics, MD simulations were performed on Trypanosoma cruzi spermidine synthase to obtain an ensemble of dominant binding sites with a high probability of existence. The structure of the binding site obtained through MD simulation revealed pockets in addition to the active site that was present in the initial structure. Using the obtained binding site structures, virtual screening of 4.8 million compounds by docking simulation, in vitro assays, and X-ray analysis was conducted, successfully identifying two hit compounds., Competing Interests: The authors declare the following competing financial interest(s): Y.H., Y.A., Y.T., K.O., I.N., T.N., and M.O. were employees of Astellas Pharma Inc. at the time this study was being conducted. The company had no role in the design of the study, namely in the collection, analysis, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results. R.Y., N.Y., T.I., D.K.I., K.K., Y.A., and M.S. declare that they have no conflict of interest., (© 2023 The Authors. Published by American Chemical Society.)

Molybdenum carbides (MoC and Mo 2 C) are being reported for various applications, for example, catalysts for sustainable energies, nonlinear materials for laser applications, protective coatings for improving tribological performance, and so on. A one-step method for simultaneously fabricating molybdenum monocarbide (MoC) nanoparticles (NPs) and MoC surfaces with a laser-induced periodic surface structure (LIPSS) was developed by using pulsed laser ablation of a molybdenum (Mo) substrate in hexane. Spherical NPs with an average diameter of 61 nm were observed by scanning electron microscopy. The X-ray diffraction pattern and electron diffraction (ED) pattern results indicate that a face-centered cubic MoC was successfully synthesized for the NPs and on the laser-irradiated area. Notably, the ED pattern suggests that the observed NPs are nanosized single crystals, and a carbon shell was observed on the surface of MoC NPs. The X-ray diffraction pattern of both MoC NPs and LIPSS surface indicates the formation of FCC MoC, agreeing with the results of ED. The results of X-ray photoelectron spectroscopy also showed the bonding energy attributed to Mo-C, and the sp 2 -sp 3 transition was confirmed on the LIPSS surface. The results of Raman spectroscopy have also supported the formation of MoC and amorphous carbon structures. This simple synthesis method for MoC may provide new possibilities for preparing Mo x C-based devices and nanomaterials, which may contribute to the development of catalytic, photonic, and tribological fields., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

This study compared the physical properties, e.g., glass transition temperature, melting point, viscosity, density, surface tension, and electrical conductivity, and the low-frequency spectra under 200 cm -1 of three synthesized ionic liquids (ILs), triethylpentylphosphonium bis(fluorosulfonyl)amide ([P 2225 ][NF 2 ]), ethoxyethyltriethylphosphonium bis(fluorosulfonyl)amide ([P 222(2O2) ][NF 2 ]), and triethyl[2-(ethylthio)ethyl]phosphonium bis(fluorosulfonyl)amide ([P 222(2S2) ][NF 2 ]), at various temperatures using femtosecond Raman-induced Kerr effect spectroscopy (fs-RIKES) and terahertz time-domain spectroscopy (THz-TDS). The [P 222(2S2) ][NF 2 ] had the highest viscosity and glass transition temperature, whereas the [P 222(2O2) ][NF 2 ] had the lowest. Among the three ILs, the [P 222(2S2) ][NF 2 ] had the highest density and surface tension, and the [P 222(2O2) ][NF 2 ] had the highest electrical conductivity. The RIKES and THz-TDS spectral line shapes for the three ILs varied significantly. For the [P 2225 ][NF 2 ], molecular dynamics simulations successfully reproduced the line shapes of the experimental spectra and indicated that the RIKES spectrum was mainly due to the cation and cross-term and their rotational motions, whereas the THz-TDS spectrum was mainly due to the anion and its translational motion. This shows that it is desirable to utilize both fs-RIKES and THz-TDS methods to reveal molecular motions at the low-frequency domain. The [P 222(2S2) ][NF 2 ] had higher frequency peaks and broader bands in the low-frequency spectra via fs-RIKES and THz-TDS than those for the [P 2225 ][NF 2 ] and [P 222(2O2) ][NF 2 ].

Biocontainment is a key methodology to reduce environmental risk through the deliberate release of genetically modified microorganisms. Previously, we developed a phosphite (HPO 3 2- )-dependent biocontainment strategy, by expressing a phosphite-specific transporter HtxBCDE and phosphite dehydrogenase in bacteria devoid of their indigenous phosphate (HPO 4 2- ) transporters. This strategy did not allow Escherichia coli to generate escape mutants (EMs) in growth media containing phosphate as a phosphorus source using an assay with a detection limit of 1.9 × 10 -13 . In this study, we found that the coexistence of a high dose of phosphate (>0.5 mM) with phosphite in the growth medium allows the phosphite-dependent E. coli strain to generate EMs at a frequency of approximately 5.4 × 10 -10 . In all EMs, the mutation was a single amino acid substitution of phenylalanine to cysteine or serine at position 210 of HtxC, the transmembrane domain protein of the phosphorus compound transporter HtxBCDE. Replacement of the HtxC F210 residue with the other 17 amino acids revealed that HtxC F210 is crucial in determining substrate specificity of HtxBCDE. Based on the finding of the role of HtxC F210 as a "gatekeeper" residue for this transporter, we demonstrate that the replacement of HtxC F210 with amino acids resulting from codons that require two simultaneous point mutations to generate phosphate permissive HtxC mutants can reduce the rate of EM generation to an undetectable level. These findings also provide novel insights into the functional classification of HtxBCDE as a noncanonical ATP-binding cassette transporter in which the transmembrane domain protein participates in substrate recognition.

Complex formation of 5- tert -butyl-1,3-phenylene bis( tert -butyl nitroxide) and rare-earth (RE) metal ions gave a linear chain where each nitroxide O atom is directly bonded to the RE ion. The bridge was proven to be a ground triplet molecule in the complexes. A hysteresis loop was recorded below 2.8 K as a single-chain magnet for the RE = Tb derivative.

The estimation of protein model quality remains a challenging task and is important for protein structural model utilization. In the last decade, existing methods that rely on machine learning to deep learning have been developed and shown progressive improvement. Despite utilizing more sophisticated techniques and introducing new features, none of these methods employ explicit protein structure stability information. Hypothetically, protein model quality might be indicated by its structural stability in an in silico system disclosed by the structural difference from its initial structure. One of the possible methods to exploit such information is by implementing molecular dynamics simulations that have shown successful applications in many research fields. We present a novel approach by introducing explicit protein structure stability information using molecular dynamics simulation. Despite using only simple features, small data with no training process required, and a short molecular dynamics simulation time, our method shows comparable performance to the state-of-the-art deep learning-based method., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

We report the synthesis and characterization of seven new tetranuclear 3d-4f complexes derived from the 3:3:1 reaction of 1,4-diformylnaphthalene-2,3-diol (H 2 L ) with copper(II) nitrate and a lanthanide salt, Ln = Tb [ L 3 Cu 3 TbCl 2 (NO 3 ) 2 (H 2 O) 2 ] ( C1 ), Ho [ L 3 Cu 3 HoCl 3 (H 2 O) 3 (MeOH)](H 2 O) ( C2 ), Er [ L 3 Cu 3 ErCl 3 (H 2 O) 3.5 (MeOH) 0.5 ](H 2 O) ( C3 ), Gd [ L 3 Cu 3 Gd(NO 3 ) 2 (H 2 O) 2 (MeOH)](NO 3 ) ( C4 ), Dy [ L 3 Cu 3 Dy(NO 3 ) 2 (H 2 O) 2 (MeOH)](NO 3 ) ( C5 ), Yb [ L 3 Cu 3 Yb(NO 3 ) 2 (H 2 O) 2 (MeOH)](NO 3 ) ( C6 ), and La [ L 3 Cu 3 La(NO 3 ) 2 (H 2 O) 2 (MeOH)](NO 3 ) ( C7 ). Structural elucidation showed that the self-assembly using the acyclic ligand system was successful for all seven complexes, which exhibit the same near-planar Cu 3 LnO 12 core. Five complexes ( C1 , C2 , and C4 - C6 ) were magnetically characterized at 300 K and 1.8 K. Complexes C1 , C4 , and C5 were observed to have ferromagnetic ground states and showed appreciable frequency dependence in their AC magnetic measurements, which yielded effective barriers between 7.82(4) and 13.2(3) K, confirming the presence of single-molecule magnet properties., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

The effect of a synthetic saponite surface on the "in-water" dehydration reaction of diol was examined using 4-formyl-1-methylquinolinium salt (MQu + ) as a substrate. The equilibrium between aldehyde (MQu + -Aldehyde) and diol (MQu + -Diol) was affected by the surrounding environment. The equilibrium behavior was observed by 1 H nuclear magnetic resonance (NMR) and UV-vis absorption measurements. Although MQu + was completely in the form of MQu + -Diol in water, the equilibrium almost shifted to the MQu + -Aldehyde side when MQu + was adsorbed on the saponite surface in water. In addition, the MQu + -Aldehyde ratio depended on the negative charge density of saponite. The factors that determine MQu + -Aldehyde: MQu + -Diol ratio were discussed from the thermodynamic analysis of the system. These data indicate that the electrostatic interaction between the charged saponite surface and MQu + stabilized the aldehyde side enthalpically and destabilized it entropically. The major reason for these results is considered to be the difference in adsorption stabilization between MQu + -Aldehyde and MQu + -Diol on saponite surfaces.

Surface-fixation induced emission is a fluorescence enhancement phenomenon, which is expressed when dye molecules satisfy a specific adsorption condition on the anionic clay surface. The photophysical behaviors of two types of cationic acridinium derivatives [10-methylacridinium perchlorate (Acr + ) and 10-methyl-9-phenylacridinium perchlorate (PhAcr + )] on the synthetic saponites with different anionic charge densities were investigated. Under the suitable conditions, the fluorescence quantum yield (Φ f ) of PhAcr + was enhanced 22.3 times by the complex formation with saponite compared to that in water without saponite. As the inter-negative charge distance of saponite increased from 1.04 to 1.54 nm, the Φ f of PhAcr + increased 1.25 times. In addition, the increase in the negative charge distance caused the increase in the integral value of the extinction coefficient and the radiative deactivation rate constant ( k f ) and the decrease in the nonradiative deactivation rate constant. It should be noted that the 2.3 times increase in k f is the highest among the reported values for the effect of clay. From these results, it was concluded that the photophysical properties of dyes can be modulated by changing the charge density of clay minerals., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

Gangliosides (glycosphingolipids) reduce antibody production by inhibiting B-cell receptor (BCR) signaling. We have shown that a copresentation of gangliosides and polyethylene glycol (PEG) on the same liposomes suppresses anti-PEG IgM production in mice. In addition, we recently observed that pDNA incorporated in PEGylated cationic liposomes (PCLs) induces anti-DNA IgM, which could be a hurdle to the development of efficient gene delivery systems. Therefore, the focus of this study was to determine if the copresentation of gangliosides and DNA on the same PCL would suppress antibody production against DNA. PCLs including DNA induced both anti-PEG IgM production and anti-DNA IgM production. The extent of anti-PEG and anti-DNA IgM production was likely dependent on the immunogenicity of the complexed DNA. Treatment of clodronate-containing liposomes, which causes a depletion of phagocytic cells, suppressed anti-PEG IgM production from PCLs that did not include DNA but failed to suppress anti-PEG IgM production from PCLs that complexed DNA (PCLD). Both anti-PEG IgM and anti-DNA IgM was induced in T-cell-deficient nude mice as well as in normal mice following treatment with PCLs and PCLD, respectively. These results indicate that phagocytic cells contribute to anti-PEG IgM production but not to anti-DNA IgM production, while T-cells do not contribute to any form of antibody production. The copresentation of gangliosides and DNA significantly reduced anti-PEG IgM production but unfortunately did not reduce anti-DNA IgM production. It appears that the immunosuppressive effect of gangliosides, presumably via the CD22 signaling pathway, is limited only to anti-PEG immunity.

Abraxane, an albumin-bound paclitaxel nanoparticle formulation, is superior to conventional paclitaxel preparations because it has better efficacy against unresectable pancreatic cancer. Previous reports suggest that this better efficacy of Abraxane than conventional paclitaxel preparation is probably due to its transport through Gp60, an albumin receptor on the surface of vascular endothelial cells. The increased tumor accumulation of Abraxane is also caused by the secreted protein acid and rich in cysteine in the tumor stroma. However, the uptake mechanism of Abraxane remains poorly understood. In this study, we demonstrated that the delivery of Abraxane occurred via different receptor pathways from that of endogenous albumin. Our results showed that the uptake of endogenous albumin was inhibited by a Gp60 pathway inhibitor in the process of endocytosis through endothelial cells or tumor cells. In contrast, the uptake of Abraxane-derived HSA was less affected by the Gp60 pathway inhibitor but significantly reduced by denatured albumin receptor inhibitors. In conclusion, these data indicate that Abraxane-derived HSA was taken up into endothelial cells or tumor cells by a mechanism different from normal endogenous albumin. These new data on distinct cellular transport pathways of denatured albumin via gp family proteins different from those of innate albumin shed light on the mechanisms of tumor delivery and antitumor activity of Abraxane and provide new scientific rationale for the development of a novel albumin drug delivery strategy via a denatured albumin receptor.

The proper application of retrosynthesis to identify possible transformations for a given target compound requires a lot of chemistry knowledge and experience. However, because the complexity of this technique scales together with the complexity of the target, efficient application on compounds with intricate molecular structures becomes almost impossible for human chemists. The idea of using computers in such situations has existed for a long time, but the accuracy was not sufficient for practical applications. Nevertheless, with the steady improvement of machine learning and artificial intelligence in recent years, computer-assisted retrosynthesis has been gaining research attention again. Because of the overall lack of chemical reaction data, the main challenge for the recent retrosynthesis methods is low exploration ability during the analysis of target and intermediate compounds. The main goal of this research is to develop a novel, template-free approach to address this issue. Only individual molecular substructures of the target are used to determine potential disconnection sites, without relying on additional information such as chemical reaction class. The model for the identification of potential disconnection sites is trained on novel molecular substructure fingerprint representations. For each of the disconnections suggested using the model, a simple structural similarity-based reactant retrieval and scoring method is applied, and the suggestions are completed. This method achieves 47.2% top-1 accuracy for the single-step retrosynthesis task on the processed United States Patent Office dataset. Furthermore, if the predicted reaction class is used to narrow down the reactant candidate search space, the performance is improved to 61.4% top-1 accuracy.

A new compound [Gd(hfac) 3 (MeOTEMPO)(MeOH)] (MeOTEMPO = 4-methoxy-2,2,6,6-tetramethylpiperidin-1-oxyl) was prepared. From the X-ray crystal structure analysis, the Gd-O-N angle is 170.9(3)°. The magnetic study clarified the Gd 3+ -radical interaction with 2 J / k B = -26.6(3) K (in the H = -2 JS 1 · S 2 convention), which corresponds to one of the strongest antiferromagnetic couplings in the Gd-nitroxide systems. Wider Gd-O-N angles seem to favor stronger antiferromagnetic couplings.

The reaction mechanism of biomass decomposition by xylanases remains the subject of debate. To clarify the mechanism we investigated the glycosylation step of GH11 xylanase, an enzyme that catalyzes the hydrolysis of lignocellulosic hemicellulose (xylan). Making use of a recent neutron crystal structure, which revealed the protonation states of relevant residues, we used ab initio quantum mechanics/molecular mechanics (QM/MM) calculations to determine the detailed reaction mechanism of the glycosylation step. In particular, our focus is on the controversial question of whether or not an oxocarbenium ion intermediate is formed on the reaction pathway. The calculations support the validity of a basic retaining mechanism within a double-displacement scheme. The estimated free energy barrier of this reaction is ∼18 kcal/mol with QM/MM-CCSD(T)/6-31(+)G**//MP2/6-31+G**/AMBER calculations, and the rate-determining step of the glycosylation is scission of the glycosidic bond after proton transfer from the acidic Glu177. The estimated lifetime of the oxocarbenium ion intermediate (on the order of tens of ps) and the secondary kinetic isotope effect suggest that there is no accumulation of this intermediate on the reaction path, although the intermediate can be transiently formed. In the enzyme-substrate (ES) complex, the carbohydrate structure of the xylose residue at the -1 subsite has a rather distorted (skewed) geometry, and this xylose unit at the active site has an apparent half-chair conformation when the oxocarbenium ion intermediate is formed. The major catalytic role of the protein environment is to orient residues that take part in the initial proton transfer. Because of a fine alignment of catalytic residues, the enzyme can accelerate the glycosylation reaction without paying a reorganization energy penalty.

The molecular catalyst sensitized system (MCSS), where an excited molecular catalyst adsorbed on a semiconductor such as TiO 2 injects electrons to the conduction band of the semiconductor leading to hydrogen evolution/CO 2 reduction coupled with an oxidation of water on the molecular catalyst, has been one of the most probable candidates in the approach to artificial photosynthesis. For a full utilization of visible light, however, a serious light scattering of the aqueous suspension of TiO 2 in the visible region, which is generally experienced, should be avoided. Here, we report a preparation of optically transparent colloidal dispersion of TiO 2 by the sol/gel reaction of TiCl 4 through progressive hydrolysis/condensation under the basic condition without any calcination processes. The TiO 2 nanoparticles (TiO 2 (NPs)) obtained were characterized as an amorphous particle (∼10-15 nm) having a microcrystal domain of anatase within several nm by XRD, Raman spectroscopies, XRF, XAFS, TG/DTA, and HRTEM, respectively. The energy-resolved distribution of carrier electron traps in TiO 2 (NPs) as a fingerprint of TiO 2 was characterized through reversed double-beam photo-acoustic spectroscopy to have a close similarity to that of TiO 2 (ST-01) as well as the observation of carrier traps by transient absorption spectroscopy. Though the powder TiO 2 (NP) itself was not dispersed well in aqueous solution, the wet TiO 2 (NPs) as prepared before being dried up provided a completely transparent aqueous dispersion under the acidic condition (1 M HCl). Addition of methanol enabled the colloidal dispersion (TiO 2 (NPs, MeOH/H 2 O, 0.1 M HCl)) to keep the optical transparency for longer than 1 year (550 days), which is the first example of TiO 2 dispersion storable for such a long period. TiO 2 (NPs, MeOH/H 2 O) exhibited a moderate photocatalytic reactivity of H 2 evolution with a quantum yield of ∼2.6% upon 365 nm light irradiation. An optically transparent thin film of TiO 2 (NPs, MeOH/H 2 O) was also successfully prepared on a glass plate to exhibit an enhanced hydrophilicity upon UV light irradiation.

Iron-catalyzed alkylative cyclization of alkenes bearing oxygen nucleophiles with secondary and tertiary alkyl bromides through carbon-carbon and carbon-oxygen bond formations has been developed. A broad substrate scope is an attractive feature of this synthetic method, providing a variety of potentially bioactive five- and six-membered oxygen-containing heterocycles. The reaction pathway is proposed to involve a radical addition of the in situ -formed alkyl radical to an alkene followed by carbon-oxygen bond-forming intramolecular cyclization.

PEGylation had been used successfully to improve the circulation half-lives and some physicochemical properties of protein therapeutics. However, anti-polyethylene glycol (anti-PEG) antibodies, either pre-existing or treatment-induced, can negatively affect the pharmacokinetics and pharmacological efficacy of PEGylated proteins. We have examined anti-PEG immune responses in mice for peginterferon alfa-2a (Pegasys), a clinically approved PEGylated protein therapeutic, at both the recommended dose (equivalent to 3 μg/kg in mice) and at higher doses (150 μg/kg) for single or repeated subcutaneous (s.c.) administrations. The effect of treatment-induced anti-PEG IgM on serum concentrations of Pegasys, following repeated administrations, was evaluated. In addition, the effect of pre-existing anti-PEG IgM elicited by a different PEGylated protein, PEG-OVA, on the systemic clearance of Pegasys, was investigated. At a s.c. dose of 3 μg/kg, single injections of Pegasys barely elicited anti-PEG immune responses. Four repeated doses of 150 μg/kg Pegasys elicited anti-PEG IgM production, depending on dose frequency, and triggered the rapid clearance of subsequent doses. In addition, anti-PEG-IgM produced in response to prior administration of PEG-OVA caused a rapid blood clearance of Pegasys. Our results, therefore, underscore the importance of screening for both pre-existing and treatment-induced anti-PEG antibodies in patients prior to and during treatment with PEGylated protein drugs.

The adsorption behavior and enzyme activity of horseradish peroxidase (HRP) was examined on a synthetic clay nanosheet, whose surface is flat at the atomic level and is negatively charged. The results showed that HRP is adsorbed effectively (adsorption equilibrium constant, K = 1.61 × 10 7 L mol -1 ) and that the structure of HRP was altered on the clay surface. The enzyme activity of HRP on the clay surface was evaluated by using H 2 O 2 and tert -BuOOH as a substrate. As a result, HRP on the clay surface was able to work for tert -BuOOH, while HRP in solution did not show any activity. In addition, HRP on SSA showed reactivity even under the high-temperature conditions. These results indicate that the clay nanosheet can be a unique modifier for enzyme activity of HRP.

In the context of magneto-structural study, a relatively short alkyl group was introduced to anionic spin-crossover (SCO) building blocks based on [Fe(py 3 CR)(NCS) 3 ] - , where py 3 CR stands for tris(2-pyridyl)methyl derivatives. The linear alkyl and acyloxyl derivatives of Me 4 N[Fe(py 3 CR)(NCS) 3 ] with R = C n H 2 n +1 ( n = 1-7) and C n H 2 n +1 CO 2 ( n = 1-6) were synthesized, and the magnetic study revealed that all the compounds investigated here exhibited SCO. The SCO temperature ( T 1/2 ) varied in 289-338 K for the alkylated compounds, and those of the acyloxylated ones were lower with a narrower variation width ( T 1/2 = 216-226 K). The crystal structures of the former with n = 3, 4, and 5 and the latter with n = 1, 4, 5, and 6 were determined, and various molecular arrangements were characterized. There is no structural evidence for a molecular fastener effect. The plots on T 1/2 against n displayed a pronounced odd-even effect; the SCO temperatures of the homologues with even n are relatively higher than those of the homologues with odd n . The odd-even effect on T 1/2 may be related with the entropy difference across the SCO, rather than crystal field modification or intermolecular interaction. The present work will help molecular design to fine-tune T 1/2 by means of simple chemical modification like alkylation and acyloxylation.

Acyl fluorides are subjected to methoxylation with tris(2,4,6-trimethoxyphenyl)phosphine (TMPP) to afford the corresponding methyl esters in good to excellent yields. This transformation is featured by C( sp 2 )-OMe bond cleavage under metal-free conditions. Unprecedented utilization of TMPP as a methoxylating agent realized the installation of an OMe group into the desired products.

We carry out detailed computational investigations of the decomposition and dissolution processes of a cellulose I β fiber in the ionic liquid (IL) solvent, [C 2 MIm][OAc]. First, we investigated the properties of the interactions between cellulose chains in the cellulose fiber, including interchain H-bonds and stacking interactions, with the quantum and molecular mechanics (QM/MM) methods, employing a microscopic solvent model. From the calculation results, it is indicated that interchain interaction energies are largely influenced in the axial direction by the solvent effects of the IL and that the degree of interactions depends on the site of the glucose unit, compared to that in the equatorial (parallel) direction. To further investigate the impact of the IL on intrachain H-bonds and its relation to interchain interaction, we perform molecular dynamics (MD) simulations. Our results indicate that it is difficult to disrupt a strong three-dimensional H-bond network in the cellulose fiber at room temperature, even with ILs. On the other hand, the total number of H-bonds in the cellulose fiber continues to decrease from the beginning of the dissolution and decomposition processes in the IL at 400 K. The results indicate that the number of inter- and intrachain H-bonds reduces sequentially and that intrachain H-bond breakage inside the cellulose fiber proceeds prior to interchain H-bond disruption. Also, it is shown that the breakage of interchain H-bonds starts playing an important role in enhancing the separation of cellulose chains from each other. On the role of anions in the dissolution and decomposition processes of the cellulose fiber in the IL, our results indicate that the formation of H-bonds between [OAc] - anions and a cellulose chain is facilitated by the intercalation of [OAc] - anions into the cellulose fiber and that, in particular, the breakage of intrachain H-bonds in cellulose chains due to [OAc] - anions proceeds prior to that of interchain H-bonds. On the role of cations, it is shown that [C 2 MIm] + cations could interact with the cellulose and stabilize detached cellulose chains due to the stacking effect through the van der Waals interaction, in particular, within the first solvation shell of a cellulose chain in ILs. Our results suggest that the enhancement of the flexibility of rigid cellulose chains triggered by the breakage of intrachain H-bonds due to anions starts decomposition processes accompanied by dissolution processes due to the intercalation of cations, synergistically, and, then, both dissolution and decomposition processes are executed simultaneously.

Chiral plasmonic nanodevices whose handedness can be switched reversibly between right and left by external stimulation have attracted much attention. However, they require delicate DNA nanostructures and/or continuous external stimulation. In this study, those issues are addressed by using metal-inorganic nanostructures and photoinduced reversible redox reactions at the nanostructures, namely, site-selective oxidation due to plasmon-induced charge separation under circularly polarized visible light (CPL) and reduction by UV-induced TiO 2 photocatalysis. We irradiate gold nanorods (AuNRs) supported on TiO 2 with right- or left-CPL to generate electric fields with chiral distribution around each AuNR and to deposit PbO 2 at the sites where the electric fields are localized, for fixing the chirality to the AuNR. The nanostructures thus prepared exhibit circular dichroism (CD) based on longitudinal and transverse plasmon modes of the AuNRs. Their chirality given by right-CPL (or left-CPL) is locked until PbO 2 is rereduced under UV light. After unlocking by UV, the chirality can be switched by left-CPL (or right-CPL) irradiation, resulting in reversed CD signals and locking the switch again. The handedness of the chiral plasmonic nanodevice can be switched reversibly and repeatedly.

Since the discovery of catalysis by Au nanoparticles (NPs), unique catalytic features of Au have appeared that are greatly different from those of Pd and Pt. In this Review, we aimed to disclose how the unique catalytic abilities of Au are generated with respect to (a) the contact structures between Au and its supports and (b) the size of the Au particles. For CO oxidation, the catalytic activity of Au on reducible metal oxides (MO x ) is strongly correlated with the amount of oxygen vacancies of the MO x surface, which play a key role in O 2 activation. Single atoms, bilayers of Au, sub-nm clusters, clusters (1-2 nm), and NPs (2-5 nm) have been proposed as the active sizes of the Au species, which may depend on the type of support. For propylene epoxidation, the presence of isolated TiO 4 units in SiO 2 supports is important for the production of propylene oxide (PO). Au NPs facilitate the formation of Ti-OOH species, which leads to PO in the presence of H 2 and O 2 , whereas Au clusters facilitate propylene hydrogenation. However, Au clusters can produce PO by using only O 2 and water, whereas Au NPs cannot. For alcohol oxidation, the reducibility of the MO x supports greatly influences the catalytic activity of Au, and single Au atoms more effectively activate the lattice oxygen of CeO 2 . The basic and acidic sites of the MO x surface also play an important role in the deprotonation of alcohols and the activation of aldehydes, respectively. For selective hydrogenation, heterolytic dissociation of H 2 takes place at the interface between Au and MO x , and the basic sites of MO x contribute to H 2 activation. Recent research into the reaction mechanisms and the development of well-designed Au catalysts has provided new insights into the preparation of high-performance Au catalysts.

The catalytic cycle of allylic arylation in water catalyzed by linear polystyrene-stabilized Pd or PdO nanoparticles (PS-PdNPs or PS-PdONPs) was investigated. Stoichiometric stepwise reactions indicated that the reaction did not proceed stepwise on the surface of the catalyst. In the case of the reaction with PS-PdNPs, the leached Pd species is the catalytically active species and the reaction takes place through a similar reaction pathway accepted in the case of a complex catalyst. In contrast, allylic arylation using PS-PdONPs as a catalyst occurs via a Pd (II) catalytic cycle., Competing Interests: The authors declare no competing financial interest., (Copyright © 2019 American Chemical Society.)

Complexation of nickel(II) bromide with tert -butyl 5-phenyl-2-pyridyl nitroxide (phpyNO) gave two morphs of doubly chelated [Ni(phpyNO) 2 Br 2 ] as a 2p-3d-2p heterospin triad. The α phase crystallizes in the orthorhombic space group Pbcn . An asymmetric unit involves a half-molecule. The torsion angle around Ni-O-N-C 2py is as small as 6.5(3)° at 100 K and 7.0(6)° at 400 K, guaranteeing an orthogonal arrangement between the magnetic radical π* and metal 3d x 2 - y 2 and 3d z 2 orbitals. Magnetic study revealed the high-spin ground state with the exchange coupling constant 2 J / k B = +288(5) K, on the basis of a symmetrical spin Hamiltonian. The β phase crystallizes in the monoclinic space group P 2 1 / n torsion angles are 24.2(6) and 37.2(5)° at 100 K and 10.4(7) and 25.9(6)° at 400 K. A magnetic study revealed a very gradual and nonhysteretic spin transition. An analysis based on the van't Hoff equation gave a successful fit with the spin-crossover temperature of 134(1) K, although the susceptibility did not reach the theoretical high-spin value at 400 K. Density functional theory calculation on the β phase showed ground 2py torsion angles are 24.2(6) and 37.2(5)° at 100 K and 10.4(7) and 25.9(6)° at 400 K. A magnetic study revealed a very gradual and nonhysteretic spin transition. An analysis based on the van't Hoff equation gave a successful fit with the spin-crossover temperature of 134(1) K, although the susceptibility did not reach the theoretical high-spin value at 400 K. Density functional theory calculation on the β phase showed ground S total = 0 in the low-temperature structure while S total = 2 in the high-temperature structure, supporting the synchronized exchange coupling switch on both sides. Consequently, the β phase can be recognized as an "incomplete spin crossover" material, as a result of conflicting thermal depopulation effects in a high-temperature region.

The title compound (Me 4 N)[Fe{(2-py) 3 C- n-C 18 H 37 }(NCS) 3 ] having a C 18 chain underwent spin-crossover (SCO). There are two crystallographically independent molecules in a triclinic cell at 100 K but only one in a monoclinic cell at 300 K. The complex showed a gradual one-step SCO in the same temperature region as that of the structural transition. The SCO is supported with the 57 Fe Mössbauer spectroscopy. The molecules are differentiated on cooling, but the SCO was synchronized.

A new spirobiradical, 2,2',7,7'-tetra( tert-butyl)-9,9'(10 H,10' H)-spirobiacridine-10,10'-dioxyl, was prepared. The crystallographic analysis clarified the D 2 d molecular structure, suggesting the degeneracy of SOMOs. The magnetic study revealed that intramolecular ferromagnetic coupling was operative with 2 J/ k B = +23(1) K. To the best of our knowledge, the ferromagnetic coupling parameter is the largest ever reported for a paramagnetic spiro compound.

Identifying nonpoint phosphorus (P) sources in a watershed is essential for addressing cultural eutrophication and for proposing best-management solutions. The oxygen isotope ratio of phosphate (δ 18 O PO 4 ) can shed light on P sources and P cycling in ecosystems. This is the first assessment of the δ 18 O PO 4 distribution in a whole catchment, namely, the Yasu River Watershed in Japan. The observed δ 18 O PO 4 values in the river water varied spatially from 10.3‰ to 17.6‰. To identify P sources in the watershed, we used an isoscape approach involving a multiple-linear-regression model based on land use and lithological types. We constructed two isoscape models, one using data only from the whole watershed and the other using data from the small tributaries. The model results explain 69% and 96% of the spatial variation in the river water δ 18 O PO 4 . The lower R 2 value for the whole watershed model is attributed to the relatively large travel time for P in the main stream of the lower catchment that can result in cumulative biological P recycling. Isoscape maps and a correlation analysis reveal the relative importance of P loading from paddy fields and bedrock. This work demonstrates the utility of δ 18 O PO 4 isoscape models for assessing nonpoint P sources in watershed ecosystems.