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Fungicides play a significant role in the integrated management of plant pathogens. However, the irrational application of the fungicides with similar structures have led to development of cross-resistance. Therefore, the need to seek novel fungicides with new structure is desired.Twenty-eight novel sulfoximine derivatives incorporating nitroguanidine moieties were designed, synthesized, and evaluated as antifungal agents. The bioassay results indicated that most of the synthesized compounds displayed excellent fungicidal activities against Sclerotinia sclerotiorum, Rhizoctonia solani, Fusarium graminearum, and Pyricularia grisea. Among them, compounds 6cNovel sulfoximine derivatives containing nitroguanidine possess the potential antifungal activity, and the unique structure may offer an alternative option for fungicide development in the future. This article is protected by copyright. All rights reserved.

The trace element boron (Boron, B) is an important factor in crops’ development, pollination, and fertilization. Available boron (AB) in soil is the main source of boron nutrient absorption for crops. Rapid detection of AB is of great significance for crop nutrition diagnosis, soil testing and fertilization, precision agriculture development, scientific production management, and guarantee of stable yield and high quality. In this study, we propose a new method to predict soil available boron content using handheld nonimaging hyperspectroscopy in the visible-near-infrared range (350–1655 nm). As boron content is one of the fewest soil chemical elements, a rapid and accurate method has yet to be developed to detect and quantify the soil available boron. Visible-near-infrared ray (VIS-NIR) spectroscopy is widely utilized in the detection and quantification of soil available nutrients. There is, however, scant research on the detection of soil boron based on NIR data, and the performance of current regression model is still far from satisfactory. Our soil samples were collected from southern Anhui, China, with their NIR spectroscopy examined and the NIR data pretreated by 29 transformations and modeled with 10 regression algorithms. Of all the tested methods, SVM_RBF, BPNN, and PLS_RBF algorithms demonstrated the best performance and gave 0.80∼0.82 coefficient of determination value. At the same time, Random Forest algorithm (RFA), Successive Projection Algorithm (SPA), and Variable Importance in Projection (VIP) were used to extract the spectral characteristic wavelength data of soil available boron, and then the characteristic wavelength data were modeled with three regression algorithms: SVM_RBF, PLS_RBF, and BPNN. A comparative analysis of the prediction performance ( R 2 , RPD, RMSE, and RPIQ) of the models established at the full band showed that the RFA-MSC/BPNN model achieved the best performance. Compared with the best full-wavelength model DT/SVM_RBF, the test set achieved a 3.06% increase in R 2 , a 7.12% drop in RMSE, a 7.71% gain in RPD, and a 7.78% increase in RPIQ. Our work sheds lights on how to achieve rapid quantification of the soil available boron concentration.

The proton affinities of sulfoxide ylides, carbonyl ylides, allyl ylides, benzenyl ylides and heterocyclic ylides with typical substituents were investigated using the SOGGA11-X functional.

Summary The first catalytic asymmetric synthesis of N–N axially chiral compounds has been accomplished via a quinidine catalyzed N-allylic alkylation reaction. These N–N axially chiral frameworks are a new addition to the families of axially chiral molecules and to the atropisomerism involving heteroatom(s), e.g., N, O, and S. The reaction takes place smoothly under mild conditions and displays excellent functional group tolerance, allowing facile access to a variety of N–N axially chiral 1-aminopyrroles and 3-aminoquinazolinones in high yields and excellent enantioselectivities. DFT calculations have been applied to understand the origin of enantioselectivity and provide guidance for the design of additional molecules of this type. The investigation of N–N axis atropisomerism holds promise for new discoveries in medicinal chemistry and asymmetric catalysis.

MYH9 is a gene that encodes for a subunit of the myosin heavy chain IIA protein. Mutations in MYH9 are associated with hematologic abnormalities, renal dysfunction, and hearing loss. Bony cochlear nerve canal stenosis (CNCS), which is diagnosed on computed tomography (CT) imaging, has been associated with congenital deafness, cochlear nerve aplasia/hypoplasia, and inner ear malformations. We report two cases of CNCS presenting with profound congenital hearing loss whom we diagnosed with mutations in MYH9 and discuss the genotype-phenotype association and implications for management.

We introduced a type of allenic ketone as a dielectrophilic C4 synthon in phosphine-mediated reactions. The high electrophilicity of the advanced intermediates created upon phosphine activation emp...

As nutrients, secondary metabolites, essential signal molecules and energy sources, fatty acids play a vital role in biomedicine, pharmacokinetics and human metabolism. The reduction of fatty acids is one of the main ways to control the synthesis of fatty aldehydes and fatty alcohols. The resulting fatty aldehydes and fatty alcohols play a key role in many fields. Therefore, the fatty acid reduction reaction is an important type of chemical reaction, and one of the thermodynamic properties of adiabatic electron affinity (AEA), which describes the ability of fatty acids to obtain electrons, has become particularly important. In our research, we first calculated the AEA of 26 carboxylic acid compounds by using theoretical methods including 5 composite ab initio methods (G3, G4, G3B3, CBS-QB3 and CBS-Q) and 34 density functional theory (DFT) methods. It is found that ωB97X provides the most accurate result with a minimum root mean square error (RMSE) of 1.35 kcal mol−1. Therefore, the ωB97X method was used to study saturated and unsaturated fatty acids with different kinds of substituents. The results show that electron withdrawing groups (EWGs), electron donating groups (EDGs) and conjugated groups (CEG) have great and different effects on the AEA. In addition, natural bond orbital (NBO) analysis and geometric structural analysis and frontier orbital energy analysis was investigated to further reveal the change pattern of AEA values of fatty acids.

Asymmetric palladium-catalyzed arylboration/cyclization of both nonactivated and activated alkenes with B

A phosphine-catalyzed highly enantioselective and diastereoselective (up to 98 % ee and20 : 1 dr) (3+2) annulation between vinylcyclopropanes and N-tosylaldimines has been developed, which allows facile access to a range of highly functionalized chiral pyrrolidines. Notably, this method makes use of vinylcyclopropanes as a synthon for phosphine-mediated asymmetric annulation reaction, which will offer new opportunities for potential applications of cyclopropanes substrates in phosphine-catalyzed organic transformations.

SnO2 microbelt coating carbon composite was fabricated via electrospinning precursor, thermal treatment, and polymer adhesion process. Primarily, the solvent of electrospinning jet quickly evaporates in a relatively high-temperature environment; intermediate microtubules simultaneously form when the solute containing tin salt and binder converge on the skin of the jet; then, the microtubules collapse into flat microbelt product under the action of atmospheric pressure. Subsequently, SnO2 microbelts can be obtained by annealing the electrospinning products. Finally, the SnO2@C microbelts are synthesized by dopamine polymerization and carbonization process. The SnO2@C microbelts present a regular strip with width ~ 1.2 μm and thickness ~ 120 nm. Because of the synergy effect of carbon coating and SnO2 microbelt design project, the composite shows superior lithium storage of 504 mAh g-1 after 100 cycles at 0.2 A g-1. The SnO2@C microbelts are expected to be competitive alternative anode material of next-generation LIBs.

Inspired by mucus, which provides an ideal supramolecular model and whose fluid-like (viscous) and solid-like (elastic) behaviors can be adjusted to meet different physiological requirements, we report oil-regulated supramolecular adhesives by the co-assembly of polyurea oligomers and carvacrol oils. The adhesive is crosslinked by weak but abundant hydrogen bonds, which can be regulated by the incorporated carvacrol oils through the competition of intermolecular hydrogen bonds, presenting a unique set of mucus-mimicking features including oil-regulated mechanics, processability, reusable adhesivity, and extreme longevity in both air and water. Owing to the intrinsic bactericidal effect of the carvacrol oils, the developed adhesives can serve as potent antibacterial coatings with both rapid contact killing (99.9% killing within 15 min) and long-term controlled release abilities (up to 70 days), enabling versatile antibacterial applications in diverse conditions. We envision that these adhesives will be useful in buildings and architectures, community and public facilities, food storage and packaging technologies, functional textiles, and practical biomedical fields.

The importance of selenium compounds in chemistry and biochemistry has become apparent. The pKa values are important for understanding the reactivity and applicability of selenium compounds. To this end, we calculated the the pKa values of 16 selenols in aqueous solution by using two kinds of DFT methods and PCM-Bondi, SMD and SMDsSAS models. It is observed that the highest precision with a lowest RMSE value of 0.38 pK units was provided by using the ωB97XD method with the SMD model. Therefore, this theoretical protocol was employed to calculate the pKa values of selenol compounds and selenoxo forms of selenocarboxylic acid compounds including R = alkyl, cycloalkyl, benzyl, allyl and aryl as well as the substituent effects. The results suggest that selenols can give higher pKa values than selenocarboxylic acids. Generally, for both substituted selenols and selenocarboxylic acids, EWGs can decrease the pKa values and EDGs can increase the pKa values, and the pKa of the EWG of –COOH is larger and the pKa values of the EDGs of –NH2 and –N(CH3)2 are smaller. In addition, linear relationships between the pKa values with the natural charges of Se atoms, EHOMO, etc. were obtained in different types of selenols and selenocarboxylic acids.

Defect engineering have profound influence on the energy storage properties of electrode hybrids by adjusting their intrinsic electronic characteristics. For iron carbide based materials, however, the effect of defect (especially cation vacancies) toward their electrochemical performance are still unclear. Herein, the feasible and scalable synthesis of Fe

MYH9 is a gene that encodes for a subunit of the myosin heavy chain IIA protein. Mutations in MYH9 are associated with hematologic abnormalities, renal dysfunction, and hearing loss. Bony cochlear nerve canal stenosis (CNCS), which is diagnosed on computed tomography (CT) imaging, has been associated with congenital deafness, cochlear nerve aplasia/hypoplasia, and inner ear malformations. We report two cases of CNCS presenting with profound congenital hearing loss whom we diagnosed with mutations in MYH9 and discuss the genotype-phenotype association and implications for management.

We successfully designed and prepared hierarchical Ni

Prussian blue (PB) is a safe photothermal agent for tumor therapy, yet poor photothermal effect and single therapeutic function severely restrict its further clinical applications. Herein, a biodegradable “Nano-donut” (CMPB-MoS2-PEG) is fabricated for magnetic resonance (MR) imaging and enhanced photothermal therapy (PTT)/ chemodynamic therapy (CDT)/chemotherapy through responsive catalysis in tumor microenvironment (TME). The “Nano-donut” is organically composed of Cu/Mn ions doped-PB and MoS2. The porous donut structure of CMPB-MoS2-PEG endows them as a carrier for delivery of doxorubicin hydrochloride (DOX) to tumor site. The framework of Nano-donut specifically decomposes in TME due to the reaction between Fe2+/Fe3+ and H2O2. The multivalent elements (Cu/Fe/Mn ions) decrease the bandgap and then enhance CDT by synergistically catalyzing H2O2 into toxic ·OH. Meanwhile, the Mn4+ also reacts with H2O2 to generate O2, improving the hypoxia of TME and enhancing the chemotherapy effect of released DOX. The MoS2 mingles in the PB, which significantly enhances photothermal conversion efficiency (η) effect of PB from 16.02% to 38.0%. In addition, Fe3+ as T2-weighted MR imaging agent can achieve MR imaging-guided therapy. The data clearly shows Nano-donut/DOX nanocomposites (NCs) have a remarkable inhibition for cancer cells and excellent biological safety in tumor treatment.

β-Lactams are important scaffolds in drug design and frequently used as reactive intermediates in organic synthesis. Catalytic reactions featuring intramolecular C–H amidation of alkyl carboxamide ...

Thiol compounds have been shown to be important in many fields such as protein chemistry and carbohydrate chemistry. Their pKa's in aqueous solution are important for understanding the properties and reactivities of thiols in complex biochemical systems. To elucidate the structure–activity relationships and substituent effects on pKa's of thiols, pKa's of 58 thiols were calculated using different DFT methods with two types of solvation models including PCM-Bondi and SMDsSAS. It was found that the M06-2X method with the SMDsSAS model can give the optimal precision with the smallest RMSE value of 0.77 pK unit. Based on this model, the pKa's of thiols (R-SH in which R = alkyl, cycloalkyl, aryl, heterocyclyl and fluorinated hydrocarbyl) were systematically investigated. The substituent effects as well as the structure–activity relationships behind these data were also examined. Significant substituent effects were found in heterocyclyl, alkynyl and fluorinated hydrocarbyl thiols with a wide pKa range of over 10.0 pK units. In addition, analyses including the natural bond orbital (NBO) and the energies of frontier orbitals were performed in order to further understand the substituent effects on pKa's. Good linear relationships between the pKa's with substituent constants σp+ and natural charges on S atoms were observed in different types of thiols.

Rhodium transition-metal-organic cooperative catalysis, which has been intensively studied by many chemists, represents a great success in C–H bond activation because of high efficiencies and selectivities. Typically, in the reaction mechanism of aldehyde and alkene catalyzed by Rh(I) complex and 2-amino-3-picoline, two kinds of metala-cyclic transition-metal complexes of (iminoacyl)rhodium(III)hydride and (iminoacyl)rhodium(III) alkyl are generally formed. The two complexes play an important role in the overall reaction, in which the Rh–C bond formations are involved. So it is meaningful to understand the strength of Rh–C bond, which can be measured by the homolytic bond dissociation enthalpies (BDEs). To this end, we first calculated 16 relative Rh–C BDEs of Tp′Rh(CNneopentyl)RH (Tp′ = hydridotris-(3,5-dimethylpyrazolyl)borate) by 19 density functional theory (DFT) methods. Furthermore, the 5 absolute Rh–C BDEs of Rh transition-metal complexes were also calculated. The results show that the B97D3 is the most accurate method to predict the relative and absolute Rh–C BDEs and the corresponding RMSE values are the smallest of 2.8 and 3.3 kcal/mol respectively. Therefore, the Rh–C BDEs of (iminoacyl)rhodium(III)hydride and (iminoacyl)rhodium(III)alkyl as well as the substituent effects were investigated by using the B97D3 method. The results indicated that the different substituents exhibit different effects on different types of Rh–C BDEs. In addition, the analysis including the natural bond orbital (NBO) as well as the energies of frontier orbitals were performed in order to further understand the essence of the Rh–C BDE change patterns.

In the dual catalytic Suzuki–Miyaura reactions, the cross-coupling of Csp3-hybridized center organotrifluoroborate salts has been implemented successfully by single-electron transfer (SET), where the redox potentials are important for understanding the reactivities of organotrifluoroborate salts. To this end, the ΔGgas values of 27 organotrifluoroborate anions were calculated by using different composite high-level ab initio and DFT methods. Among different DFT methods, the M05-2X method gave the highest precision with a smallest RMSE of 1.58 kcal mol−1. Then, the 24 E° values of organotrifluoroborate anions were calculated by using the M05-2X method with two types of solvation models including PCM and SMD. It was found that the M05-2X method with a PCM–UAHF model can provide the most accurate results with the lowest RMSE value of 0.16 V. Therefore, the E° values of Csp3-hybridized center organotrifluoroborate anions (R–CH2–BF3−) including R = alkenyl, alkynyl, aryl and heterocyclyl and the Csp2-hybridized center vinyltrifluoroborate anions were systematically investigated with this theoretical protocol. The results indicated that for the Csp3-hybridized center organotrifluoroborate anions, the E° values range from 0.36 V to 1.57 V, and the electron-donating groups (EDG) of –N(CH3)2, –NHCH3etc. can significantly lower the E° values of organotrifluoroborate anions, which are favorable for reactions, whereas the electron-withdrawing groups (EWG) of –NO2, –CN etc. make the organotrifluoroborate anions unfavorable for reactions. For the Csp2-hybridized center organotrifluoroborate anions, the E° values range from 1.38 V to 2.43 V. In addition, the analysis of the natural bond orbital (NBO), the ground-state effect (GE), the radical-state effect (RE) and the energies of frontier orbitals was performed in order to further disclose the essence of the E° value change patterns. The linear relationships between the E° values with substituent constants σ+p and the natural charges of the corresponding C atoms of radicals, etc. were found in different types of organotrifluoroborate anions.

Defect engineering have profound influence on the energy storage properties of electrode hybrids by adjusting their intrinsic electronic characteristics. For iron carbide based materials, however, the effect of defect (especially cation vacancies) toward their electrochemical performance are still unclear. Herein, the feasible and scalable synthesis of Fe x C@NC with 3D honeycomb-like carbon architecture and abundant Fe vacancies via template etching is reported. Such structure enable outstanding lithium-ion storage properties owing to hierarchical pores, improved intrinsic electrochemical activity, as well as the introduction of more active sites. As a result, the Fe x C@NC-2 presents a high reversible specific capacity of 1079 mAh g−1 after 1000 cycles. Moreover, an excellent cycling stability can be achieved via maintaining a high-capacity retention (689 mAh g−1, 98.4%) over 1000 cycles at 5 A g−1. This study provides a feasible strategy for developing high-performance hybrids with hierarchical pore and rich defects structures.

We successfully designed and prepared hierarchical Ni3S2 nanorod@nanosheet arrays on three-dimensional Ni foam via facile hydrothermal sulfuration. We conducted a series of time- and temperature-dependent experiments to determine the Ostwald ripening process of hierarchical Ni3S2 nanorod@nanosheet arrays. The rationally hierarchical architecture creates an excellent supercapacitor electrode for Ni3S2 nanorod@nanosheet arrays. The areal capacitance of this array reaches 5.5 F cm−2 at 2 mA cm−2, which is much higher than that of Ni3S2 nanosheet arrays (1.5 F cm−2). The corresponding asymmetric supercapacitor exhibits a wide potential window of 1.6 V and energy density up to 1.0 Wh cm−2 when the proposed array is utilized as the positive electrode with activated carbon as the negative electrode. This electrochemical performance enhancement is attributable to the hierarchical structure and synergistic cooperation of macroporous Ni foam and well-aligned Ni3S2 nanorod@nanosheet arrays. Our results represent a promising approach to the preparation of hierarchical nanorod@nanosheet arrays as high-performing electrochemical capacitors.

The first highly enantioselective phosphine-catalyzed formal [4+4] annulation has been developed. In the presence of amino-acid-derived phosphines, the unprecedented [4+4] annulations between benzofuran/indole-derived α,β-unsaturated imines and allene ketones proceeded smoothly, thus affording azocines, bearing either a benzofuran or an indole moiety, in excellent yields and with nearly perfect enantioselectivities (≥98 % ee in most cases). This work marks the first efficient asymmetric construction of optically enriched eight-membered rings by phosphine catalysis.

Homogenous metal hydride (M-H) catalyst for isomerization normally required rigorous air-free techniques. This work demonstrated a highly efficient protocol that simple non-redox metal ions as Lewis acids can dramatically promote olefin isomerization by commercially available RuH2(CO)(PPh3)3 complex in open flask system. Isomerization can be accomplished within short time, and satisfying selectivity for different types of unsaturated compounds can be obtained. Meanwhile, an excellent turnover number (TON) up to 17208 was achieved under air, and open flask gram scale experiments further demonstrated the efficiency of RuH2(CO)(PPh3)3/non-redox-metals system. Through FT-IR, GC-MS, NMR and kinetics studies, it was evidenced that in sluggish RuH2(CO)(PPh3)3 catalyst, bloated PPh3 ligands caused the steric hindrance for the coordination of free alkene. Alternatively, the addition of non-redox metal ions induced the dissociation of PPh3 ligand, offered unoccupied coordination sites for alkene, and formed the magnesium-bridged adduct OC-Ru-H2---Mg2+ as the highly active species which significant benefited the isomerization through metal hydride addition-elimination pathway. Last but not least, this strategy was also demonstrated as an impactful approach for hydride catalysts of other transition metals such as osmium.

The organic synthesis reactions of diboron(4) compounds in which B–B cleavage is involved can introduce a new set of boron-containing organic reagents that were proven to be very useful in many organic synthetic routes and can be regarded as ideal candidates for green chemistry. So it is very valuable and significant to understand one of the thermodynamic properties of the B–B bond, the strength of the B–B bond, which can be measured by using the homolytic bond dissociation enthalpies (BDEs). To this end, the 34 B–B BDEs of diboron(4) compounds were calculated by theoretical methods including composite high-level ab initio and density functional theory (DFT) methods. The results show that it is reasonable and reliable to regard the 34 B–B BDE averages of the five high-level methods including G3, G3B3, CBS-Q, CBS-QB3 and ROCBS-QB3 as the standard reference values and the SOGGA11-X method provides the best accuracy with the smallest root mean square error (RMSE) of 4.4 kJ mol−1. Subsequently, the B–B BDEs of three types of diboron(4) compounds according to their different molecular symmetry were investigated in detail by using this method. The results indicate that the different substituents have different effects on B–B BDE values. Natural bond orbital (NBO) analysis and investigations of the ground-state effect (GE) and the radical-state effect (RE) as well as frontier orbital energy analysis were performed in order to further disclose the essence of corresponding BDE change patterns. In addition, in order to better understand the catalytic process involving B–B cleavages by transitional-metal catalysts, the Pt–B and Cu–B BDE predictions after B–B cleavage were also conducted at this level. The results demonstrate that the participation of transition metals such as Pt and Cu can make the B–B cleavage much easier and the different substituents have different effects on the stability of transition metal boryl complexes.

Based on many transition-metal-catalyzed Suzuki–Miyaura cross-coupling reactions of organoboron compounds in which C–B cleavages are involved, it is meaningful to understand one of the thermodynamic properties of the C–B bond, the strength of the C–B bond, which can be measured using homolytic bond dissociation enthalpies (BDEs). To this end, we first calculated 64 C–B BDEs of organoboron compounds by theoretical methods including composite high-level ab initio methods of G3, G4, G3B3, CBS-Q, CBS-QB3, and CBS-4M and 34 density functional theory (DFT) methods. The results show that it is reasonable and credible to regard the average values of six composite high-level methods as the standard C–B BDE values. By comparing the DFT methods, it is found that the M06-HF method provides the most accurate results and the root mean square error (RMSE) is the smallest of 6.4 kJ mol−1. Therefore, the C–B BDEs including C(sp)–B, C(sp2)–B and C(sp3)–B of organoboron compounds such as boronic acids, trifluoroborate salts, boronate esters, etc. as well as the substituent effects were investigated by using the M06-HF method. The results indicated that the different substituents including electron-donating groups (EDGs), electron-withdrawing groups (EWGs) and conjugated effect groups (CEGs) exhibit different effects on different types of C–B BDEs. Moreover, the natural bond orbital (NBO) analysis was performed in order to further disclose the essence of BDE change patterns.

Nanostructured electrode materials suffer low mass loading and areal capacity. In this work, large scale Ni3S2 nanoneedle-sheets array on foam Ni was fabricated via facile hydrothermal method, benefitting from the long size Ni3S2 nanoneedle and nanosheets secondary structure, this novel self-supporting Ni3S2 nanoneedle-sheets array possesses extraordinary reversible areal capacity of over 15 mAh cm−2 when applied as electrode for Lithium-ion batteries.

The C–H bond dissociation enthalpies (BDEs) of the 26 N, O, S-containing mono-heterocyclic compounds were evaluated using the composite high-level ab initio methods G3 and G4. The C–H BDEs for 32 heterocyclic compounds were calculated using 8 types of density functional theory (DFT) methods. Comparing with the experimental values, the BMK method gave the lowest root mean square error (RMSE) of 7.2 kJ/mol. Therefore, the C–H BDEs of N-fused-heterocyclic compounds at different positions were investigated by the BMK method. By NBO analysis two linear relationships between the C–H BDEs of quinoline and isoquinoline with natural charges qC/e in molecules and with natural charges qC/e in radicals were found. The substituent effects on C(α)–H BDEs in N-fused-heterocyclic compounds were also discussed. It was found that there are two linear relationships between the C(α)–H BDEs of quinoline and isoquinoline derivatives with natural charges qC(α)/e for the EDGs and CEGs substituents.

The C–O homolytic bond dissociation enthalpies (BDEs) were evaluated by composite high-level G4 and 14 density function theory (DFT) methods. By comparing these DFT methods, the wB97 provided the most accurate results and the root mean square error (RMSE) is 7.6 kJ mol−1 for C–O BDE calculations. Therefore, alkenyl and aryl C(sp2)–O cleavage and the substituent effect of carboxylates/carbamates were investigated by a wB97 method. Based on the mechanism of the Ni-catalyzed Suzuki–Miyaura cross-coupling reactions, the aryl C(sp2)–O BDEs and the substituent effect of Ni complexes of carboxylates/carbamates formed in the oxidative addition step were also discussed. In addition, the NBO analysis further disclosed the essence of the substituent effects on C–O BDEs.

Antimony (Sb) anode has attracted increasing attention given its high theoretical capacity and suitable working potential. Nonetheless, its practical application is largely hindered by huge volume changes during the cyclic process, resulting in unsatisfactory long-term cycled stabilities at high current density. In this work, large-scale ultrafine Sb nanoparticles are functionally designed to encapsulate into a 3D carbon microfiber framework (CMF) via a scalable electrospinning approach followed by a thermal treatment process. This fabrication strategy effectively avoids the change in the volume of the Sb anode and provides a fast conductive network to serve as an efficient 3D e/Li+ transport pathway. Benefiting from this novel structural design, an ultrafine Sb nanoparticles@carbon microfiber framework (U-Sb-NPs@CMF) composite anode used for lithium-ion batteries (LIBs) delivers a high reversible capacity of 622 mAh g-1 after 200 cycles at 0.5 A g-1 and 507 mAh g-1 after 2000 cycles at 2 Ag-1 and a high-capacity retention of 350 mAh g-1 even after 5000 long-term cycles. These outstanding charge-discharge performances suggest that the U-Sb-NPs@CMF composite is a promising candidate for an anode material in the application of LIBs.

Summary Chiral phosphoric acid-catalyzed highly enantioselective formal [3 + 2] cycloaddition reaction of azoalkenes with 3-vinylindoles has been established. Under mild conditions, the projected cycloaddition proceeded smoothly, affording a variety of 2,3-dihydropyrroles in high yields and excellent enantioselectivities, and also in a diastereospecific manner. As opposed to the common 4-atom synthons in the previous literature reports, azoalkenes served as 3-atom synthons. Besides, the observed selectivity was supported by primary theoretical calculation. The unique chemistry of azoalkenes disclosed herein will empower asymmetric synthesis of nitrogen-containing ring structural motifs in a broader context., Graphical Abstract, Highlights • Chiral phosphoric acid catalyzed formal [3 + 2] cycloaddition reaction • 2,3-Dihydropyrroles were enantioselectively synthesized • Azoalkenes served as 3-atom synthons, Organic Chemistry; Organic Synthesis; Physical Organic Chemistry

The first phosphine-catalyzed enantioselective formal oxa-[4 + 2] reaction between nitroethylene and α-cyano-α,β-unsaturated ketones has been developed. In the presence of a dipeptide-based phosphine catalyst and achiral Brønsted acid additives, highly functionalized 3,4-dihydro-2 H-pyrans were obtained with excellent enantio- and diastereoselectivities.

The C–O homolytic bond dissociation enthalpies (BDEs) of many ethers were calculated by high-level ab initio methods including G4, G3, CBS-Q, CBS-4M as well as 26 density function theory (DFT) methods. Among the DFT methods, wB97 provided the most accurate results and the root mean square error (RMSE) is 9.3 kJ mol−1 for 72 C–O BDE calculations. Therefore, extensive C(sp2)–O BDEs and the substituent effect of alkenyl ethers, para-position phenyl ethers/phenols as well as several typical heterocyclic ethers were investigated in detail by wB97 methods, which is important for the understanding of the chemical process involved in the cross-coupling reactions. For alkenyl ethers, the different substituents exhibited significant effects on C(sp2)–O BDEs, especially, the conjugate effect of the substituents on the O atom can greatly decrease the C(sp2)–O BDEs. In addition, the NBO analysis produced good linear correlations between the C(sp2)–O BDEs and qC × qO values (the qC and qO values denoted the natural charge of C and O atoms of the C–O bond, respectively). For para-position phenyl ethers and phenols, excellent linear relationships between the C(sp2)–O BDEs with substituent constant σp+ are found. Further discussion of the substituent effect separated into the ground effect and the radical effect can further help us to understand the essence. For several five-membered typical heterocyclic ethers, a larger bond angle change will lead to a smaller C–O BDE.

Non-redox metal ions can affect the reactivity of active redox metal ions in versatile biological and heterogeneous oxidation processes; however, the intrinsic roles of these non-redox ions still remain elusive. This work demonstrates the first example of the use of non-redox metal ions as Lewis acids to sharply improve the catalytic oxygen atom transfer efficiency of a ruthenium complex bearing the classic 2,2'-bipyridine ligand. In the absence of Lewis acid, the oxidation of ruthenium(ii) complex by PhI(OAc)2 generates the Ru(iv)[double bond, length as m-dash]O species, which is very sluggish for olefin epoxidation. When Ru(bpy)2Cl2 was tested as a catalyst alone, only 21.2% of cyclooctene was converted, and the yield of 1,2-epoxycyclooctane was only 6.7%. As evidenced by electronic absorption spectra and EPR studies, both the oxidation of Ru(ii) by PhI(OAc)2 and the reduction of Ru(iv)[double bond, length as m-dash]O by olefin are kinetically slow. However, adding non-redox metal ions such as Al(iii) can sharply improve the oxygen transfer efficiency of the catalyst to 100% conversion with 89.9% yield of epoxide under identical conditions. Through various spectroscopic characterizations, an adduct of Ru(iv)[double bond, length as m-dash]O with Al(iii), Ru(iv)[double bond, length as m-dash]O/Al(iii), was proposed to serve as the active species for epoxidation, which in turn generated a Ru(iii)-O-Ru(iii) dimer as the reduced form. In particular, both the oxygen transfer from Ru(iv)[double bond, length as m-dash]O/Al(iii) to olefin and the oxidation of Ru(iii)-O-Ru(iii) back to the active Ru(iv)[double bond, length as m-dash]O/Al(iii) species in the catalytic cycle can be remarkably accelerated by adding a non-redox metal, such as Al(iii). These results have important implications for the role played by non-redox metal ions in catalytic oxidation at redox metal centers as well as for the understanding of the redox mechanism of ruthenium catalysts in the oxygen atom transfer reaction.

The C-O homolytic bond dissociation enthalpies(BDEs) were calculated by high-level ab initio including G4, G3B3, G3, CBS-QB3 and a series of density function theory (DFT) methods. It is found that the wB97 method gave the most reliable C-O BDEs and the root-mean-square deviation (RMSD) is 7.6 kJ/mol. Therefore, the C(sp(2))-O BDE predictions and the substituent effects of alkenyl phosphates/sulfonates and aryl phosphates/sulfonates were investigated in detail by using the wB97 method. Interestingly, there exist different substituent effects in α- and β-substituted alkenyl phosphates/sulfonates. Excellent linear relationships between the C-O BDEs of β-substituted alkenyl phosphates/sulfonates with substituent constant σp(+) were found. In addition, the NBO analysis further disclosed the essence of the substituent effects on C-O BDEs.

Pollutants that exist in anionic species are issues of concern in water treatment. Compared to cationic pollutants, the removal of anionic pollutants by adsorption is more difficult because most adsorbents carry predominantly negative charges in neutral and alkaline environments. In this study, a cross-linked chitosan derivative with quaternary ammonium and magnetic properties (QM-chitosan) was prepared and employed to remove chromium (VI) and phosphorus (V) (Cr(VI) and P(V)) from aqueous environments. The QM-chitosan was characterized by Fourier transform infrared spectrometry (FT-IR), thermogravimetric analysis (TGA), energy dispersive X-ray (SEM-EDX) and zeta potential. Batch experiments show that QM-chitosan can effectively remove Cr(VI) and P(V), and the main mechanism was believed to be electrostatic interaction. A pseudo second-order model was fitted to describe the kinetic processes of Cr(VI) and P(V) removal. The adsorption isotherms of both Cr(VI) and P(V) on the QM-chitosan were well fitted by the Langmuir isotherm equation. The saturated adsorption capacity of P(V) (2.783 mmol/g) was found to be higher than that of Cr(VI) (2.323 mmol/g), resulting from the size of the H(2)PO(4)(-) ions being smaller than that of the HCrO(4)(-) ions. However, the theoretical calculation and experimental results showed that QM-chitosan had a stronger affinity for Cr(VI) than P(V). The adsorption-desorption of the QM-chitosan was evaluated, and high regeneration rates were demonstrated.