Search

Noninvasive antibacterial therapies, such as photothermal therapy (PTT), have shown great promise to treat pathogens due to low toxicity and low drug resistance. Photothermal transducing agents (PTAs) play a pivotal role to make PTT a spatiotemporally controllable and effective technique. In this study, we designed and prepared a novel nanostructured material by using a cyanine dye (Flav7) as a PTA for the treatment of S. aureus infection. 1,2-Distearoyl-sn-glycero-3-phosphoethanolamine polyethylene glycol galactose (DSPE-PEGG) was used to fabricate the nanoparticles (Flav7@DSPE-PEGG NPs) by encapsulating Flav7, and the Flav7@DSPE-PEGG NPs exhibited excellent water-dispersibility, photothermal stability, and biocompatibility. The results show that the constructed Flav7@DSPE-PEGG NPs retained good targeting capability and achieved a remarkable 99.9% eradication rate against S. aureus under 808 nm laser irradiation, and efficiently promoted infected wound healing by PTT. [ABSTRACT FROM AUTHOR]

A unique electrochemical four-component reaction of terminal alkynes, (thio)xanthenes, nitriles, and water has been established in the absence of any catalyst or external oxidant. This electrochemical reaction features high atom economy and mild conditions, affording oxazole derivatives in moderate to good yields. [ABSTRACT FROM AUTHOR]

Magnéli phase titanium oxide (TinO2n−1, 4 ≤ n ≤ 10) has wide application prospects in energy storage, catalysis and other fields. During the preparation of the TinO2n−1 phase from TiO2 by the carbothermal reduction reaction (CRR), the coexistence of multiple phases caused by the change in the reduction degree is the theoretical and practical basis for obtaining TiO2/TinO2n−1 composite materials. In this work, the H2Ti3O7 nanofiber has been employed as a precursor for the following CRR process. The X-ray diffraction (XRD), Raman spectroscopy, Thermogravimetric (TG) and Differential Scanning Calorimetry (DSC) analysis results confirmed the phase transformation process of H2Ti3O7 → TiO2(B) → anatase → rutile → TinO2n−1. Comprehensive transmission electron microscopy (TEM) characterization was carried out to investigate the phase composition and interface structures of the products calcinated at different temperatures. TiO2/Ti5O9 and λ-Ti3O5/γ-Ti3O5 interfaces with specific orientation relationships have been observed. In addition, the phase transition mechanism has also been revealed based on the structural analysis results. By carefully considering the crystal structure and symmetry of the parent and new phase, the initial lattice strain matrix based on the two observed interfaces has been established accordingly. The crystallographic features of the two types of interfaces have been calculated based on modified invariant line theory, which has confirmed the consistency of the experimental observation and calculated results. The research in this paper can further expand the applicability of the three-dimensional invariant line theory in low symmetry crystal materials. [ABSTRACT FROM AUTHOR]

Herein, we report a mild dearomative [5+2]/[2+2] cycloaddition of 1H-indoles with ortho-(trimethylsilyl)aryl triflates. The unique [5+2] cycloaddition enables the synthesis of a series of dibenzo[b,e]azepine derivatives in moderate to good yields. Increasing the steric hindrance at the C2-position of 1H-indoles leads to the [2+2] cycloaddition. Mechanistic investigations support that the reaction of 1H-indoles with arynes undergoes a [2+2] cycloaddition step, followed by a ring expansion to the [5+2] cycloaddition product. [ABSTRACT FROM AUTHOR]

The design of silicon-chalcogenide-based materials is an important topic for functionalized silicon materials, but the mechanism of this process is not so clear yet. In the present work, mechanistic studies were performed on the modification of the H-terminated Si(100) surface by many organic sulfide molecules by using the density functional theory method. Calculations indicate that the mechanism involves two steps: (1) a concerted rather than a stepwise Si–S bond formation and S–S bond dissociation process and (2) an H abstraction process from the direction along rather than perpendicular to the SiH2–Si–SiH2 skeleton. The first step is the rate-determining step for all the reactions considered. For the reactions of disulfide molecules (RSSR), the steric effect of the R group is the main origin of the different reactivity, while the electronic effect of the R group has just a slight effect on the reaction's reactivity. In the reactions of sulfide molecules (RSXR′, X = S, P, Si, O, N, C), for substrates containing X elements in the same period of the periodic table, the activation barrier increases along with the decrease of the atomic number. Charges on the S atom and dissociation energies of the S–X bonds have a great impact on the reactivity of these reactions. [ABSTRACT FROM AUTHOR]

The electrochemical nitrogen reduction reaction (NRR) is a promising but extremely challenging approach for ammonia synthesis under ambient conditions. Herein, we report the excellent NRR performance of gold nanoparticles (AuNPs) with multiple high-index facets, prepared by a modified seed-mediated method. At −0.3 V vs. RHE and in 0.1 M Li2SO4 aqueous solution, the AuNPs afford the highest faradaic efficiency (FE) of 73.32% reported so far, with a remarkable ammonia generation rate of 9.22 μg h−1 cm−2. Density functional theory (DFT) calculations reveal that the high-index faceted surfaces of the AuNPs have greater preference for the adsorption of NRR intermediates (*NNH) and significantly hinder the adsorption of competing hydrogen evolution intermediates (*H). [ABSTRACT FROM AUTHOR]

Chiral Ni(ii)-complexes of N,N′-dioxides show high catalytic activity and enantioselectivity in catalysing the asymmetric Friedel–Crafts C3-alkylation of 2,5-dimethyl pyrrole to β,γ-unsaturated α-ketoesters. A dramatic reversal of enantioselectivity is realized with ligands derived from the same type of chiral source of l-ramipril, by slightly tuning the amide units. [ABSTRACT FROM AUTHOR]

A metal (Co)–Organic Framework (Co-MOF) was first found to catalyze the chemiluminescence (CL) of luminol. On the basis of X-ray photoelectron spectroscopy, powder X-ray diffraction, CL spectral, UV-visible absorption spectral, and electron spin resonance (ESR) spectral studies, as well as the research of the influence of various free radical scavengers, a possible CL mechanism was proposed. The enhanced CL might be attributed to the formation of a peroxide analogous complex between the oxygen-related radicals and the active metal site of the Co-MOF material. The established Co-MOF–luminol CL system was successfully applied to determine l-cysteine (CySH), based on the selective and sensitive enhancing effect of CySH on this CL system. Under the optimized conditions, CySH was selectively detected in the range 0.1–10 μM with a detection limit of 18 nM. This novel CL system obviously gives impetus to the new research field of metal–organic frameworks (MOFs) in chemiluminescence. [ABSTRACT FROM AUTHOR]

The design and synthesis of novel energetic materials with high energy and acceptable sensitivity is significant for the military and civil fields. In this study, a methylene-bridged asymmetric heterocyclic explosive based on strong intermolecular interactions, namely N-(1-((5-(nitroimine)-1,2,4-oxadiazol-3-yl) methyl)-1H-tetrazol-5-yl)nitroimine (4), was designed and synthesized. Its ammonium salt (5) and potassium coordination polymer (6) were also synthesized. The structures of compounds 4, 5 and 6 were determined by single crystal X-ray diffraction analyses. Independent gradient model (IGM) analyses and Hirshfeld surfaces (HS) analyses combined with single crystal analyses revealed the existence of intermolecular interactions in the three compounds. The strong intermolecular hydrogen-bonding, π⋯π, and p⋯π interactions enhance the molecular packing efficiency of 4, leading to high density and acceptable sensitivity. Detonation properties calculated with the professional software package EXPLO5 showed that the new metal-free explosive 4 exhibits superior detonation performance (D = 9296.8 m s−1; P = 38.3 GPa) which is comparable to that of HMX. [ABSTRACT FROM AUTHOR]

A simple, yet efficient synthetic approach for the construction of vinylene-linked conjugated porous networks was developed. Based on the Horner–Wadsworth–Emmons reaction, the condensation polymerization for the formation of an sp2 carbon-linkage can be achieved at room temperature. The resulting vinylene-linked frameworks exhibit a promising porous nature with the best surface area of up to 1373 m2 g−1. Their intrinsic conjugated architectures and semiconducting properties lead to photocatalytic evolution of hydrogen from water under visible light irradiation. This new synthesis method provides a facile means to prepare attractive sp2 carbon linked porous organic frameworks. [ABSTRACT FROM AUTHOR]

Antimonic acid and N-doped antimonic acid, solid acids with d10electron configuration, are reported as novel photocatalysts for rhodamine B (RhB) degradation under visible light irradiation. They show much higher activities in comparison with P25 and photolysis. However, the extent of degradation abilities for RhB was not consistent with the formation rate of the active OH radicals under visible light irradiation. [ABSTRACT FROM AUTHOR]

Nitroamine-containing compounds are a class of high energy materials usually exhibiting high impact sensitivity. Exploring low-sensitive nitroamine explosives is meaningful since explosives have helped to reduce labor costs and enhanced production efficiency greatly. In this study, two new nitroamine explosives, 2,6-bis(3-amino-4-nitramino 1,2,4-triazol-5-yl)-pyridine (2a) and 2,5-bis(3-amino-4-nitramino-1,2,4-triazol-5-yl)-pyrazine (2b), and their salts were designed and synthesized. The molecular structures of compound 2a and ammonium salt of 2b (4b) were confirmed using single-crystal X-ray diffraction. It is found that their molecular backbones stack into a layered structure while the nitroamine groups locate between layers leading to a sandwich-like structure. Low impact sensitivity of all the materials is verified with standard BAM measurements. Salts 4a, 4b, and 5b exhibit good heat resistance. Theoretical calculations show that all the compounds have high positive enthalpies of formation (from 647.9 to 1052.7 kJ mol−1) which offer them good detonation performances. In addition, Hirshfeld and IGM (independent gradient model) analyses were carried out to discover the intermolecular interaction of 2a and 4b and have clarified the relationship between the structures and molecular stabilities. [ABSTRACT FROM AUTHOR]

As a kind of metal-free material, graphitic carbon nitride (g-C3N4) is widely used in catalytic materials, energy storage materials and other fields. However, the limited light absorption, low conductivity and high recombination rate of the photogenerated electron–hole pairs limit its further application. Constructing g-C3N4 based composite materials by integrating it with carbon materials is an effective and common way to overcome the above shortcomings of g-C3N4. In this paper, carbon materials, such as carbon dots, carbon nanotubes, graphene, and carbon spheres, are integrated with g-C3N4 to construct carbon/g-C3N4 composite materials (CCNCS) and their photoelectrocatalytic performance is reviewed. The effects of those factors such as the categories of carbon materials, carbon content, nitrogen content, the morphology of g-C3N4, and the interfacial interactions between carbon and g-C3N4 on the photo/electrocatalytic performance of CCNCS are carefully analyzed to help researchers to touch the nature of the synergistic effect of g-C3N4 and the carbon ingredient in CCNCS. [ABSTRACT FROM AUTHOR]

A new fluorine–boron compound BOPHY-PTZ was designed and synthesized. The fluorescent dye was used as a highly sensitive probe for Cu2+ ion detection. The mechanism of detection involved Cu2+ ion oxidation of the phenothiazine (PTZ) moiety and blocked the intramolecular charge transfer (ICT) process from the electron-donating PTZ moiety to the electron-accepting BOPHY moiety. BOPHY-PTZ showed a weak fluorescence in solution. However, it displayed a strong fluorescence signal enhancement upon the addition of Cu2+ ions, and 1.0 nM concentration of Cu2+ can be clearly detected. The assay is simple, sensitive and convenient, and it exhibits excellent selectivity for Cu2+ ions over the other metal ions. The BOPHY-PTZ probe could be used for Cu2+ ion detection in practical samples and for environmental monitoring related applications. [ABSTRACT FROM AUTHOR]

Violet phosphorus, a non-metallic elemental layered structure, has not been reported as a photocatalyst due to the lack of its resources. An excellent photocatalytic H2 evolution rate of 675 ± 109 μmol h−1 g−1 with high stability has been achieved by the violet phosphorus simply dispersed in deionized water with addition of 1.0 wt% of co-catalyst Pt, which is much higher than that obtained from black phosphorus. The H2 evolution rate was observed to reach values as high as 553 μmol h−1 g−1 with addition of 0.5 wt% co-catalyst Pt. [ABSTRACT FROM AUTHOR]

Large single crystals of high quality are essential for studying the fundamental physical properties of materials and their further applications. However, it is always a big challenge to grow high-quality large single crystals. Increasing the crystal growth time and feedstock is an effective path to increase the crystal size and quality. A heteroelement was introduced to increase the crystal growth temperature range and feedstock to yield high-quality large single crystals in this study. Phosphorus was introduced to produce the P–Sb–Sn–I vapor phase at temperatures above 550 °C, and the Sb source for the crystal growth was significantly increased compared to the Sb–Sn–I vapor phase without phosphorus. The nucleation temperature of Sb was also significantly increased to extend the crystal growth temperature range due to the increased concentration of Sb as a result of the separation out of phosphorus from the P–Sb–Sn–I vapor phase to grow violet phosphorus at a temperature under 530 °C. High-quality β-antimony single crystals with a size of almost a centimeter have then been successfully synthesized using the hetero-phase growth method. The lattice structure of β-antimony single crystals has been obtained by single-crystal x-ray diffraction to be trigonal with a space group of R3¯m. Sharp (003) and (006) peaks with full width at half maximum of 0.063° and 0.060° have been detected from the X-ray rocking curve of the as-produced β-antimony single crystals, indicating a low dislocation density and residual stress in the crystals. The hetero-phase growth method has been demonstrated to be an effective path to yield high-quality large antimony single crystals, which can also be adopted to produce other high-quality large single crystals. [ABSTRACT FROM AUTHOR]

Using probes based on persistent luminescence nanoparticles (PLNPs) is a promising methodology for direct imaging analysis of bio-molecules. In the present work, SrMgSi2O6:Eu0.01,Dy0.02 persistent luminescence microspheres have been synthesized via a simple template method and sunlight could successfully excite their luminescence. Further, a new probe was established based on turn-off of the persistent luminescence emission for detection and optical imaging of dopamine (DA). Mechanistic studies indicated that when the synthesized PL microspheres themselves are alkaline, the PL of the SrMgSi2O6:Eu0.01,Dy0.02 microspheres can be efficiently quenched by DA through electron transfer in the presence of ambient O2. The approach exhibited high convenience by only homogeneously mixing DA and the SrMgSi2O6:Eu0.01,Dy0.02 microspheres. Meanwhile, other phenols, ascorbic acid (AA), and uric acid (UA) were tested and had little interference to the dopamine detection. The current strategy showed the linear range of PL intensity versus concentration was 1.0 × 10−5–1.0 × 10−3 M for DA with a detection limit of 0.78 μM (S/N = 3) and it was successfully applied for imaging and detection of DA in human urine with quantitative recovery (99.6–102.5%). [ABSTRACT FROM AUTHOR]

Disc-like CoII7 core-derived (4,4)- and (3,6)-connected layers, {[Co7(C2H5OH)1.5(H2O)0.5(Hdatrz)2(μ3-OH)4(ip)5]·2.5H2O·C2H5OH}n (1) and [Co7(H2O)4(ade)2(μ3-OH)6(sip)2]n (2) (Hdatrz = 3,5-diamino-1,2,4-triazole, ade− = adeninate, ip2− = isophthalate and sip3− = 5-sulfoisophthalate) were solvothermally generated and structurally and magnetically characterized. The effect of magnetic anisotropy and exchange coupling from the local CoII7 cores on the resulting magnetism properties are discussed. A crystallographically asymmetric CoII7 core in 1 exhibited an unusual single-molecule magnet (SMM)-like response under zero dc field resulting from strong anisotropy generated by two different types of CoII polyhedra and highly anisotropic exchange interactions. By contrast, a highly symmetric CoII7 disc in 2 belonging to the C2h point group showed only strong ferromagnetic exchange, to lead to an overall ST = 7/2 spin ground-state at low temperature. Thus, the interplay of magnetic anisotropy and exchange coupling has a great and complicated influence on the overall magnetic phenomena, which should be fully considered for the design and preparation of new CoII-SMMs. [ABSTRACT FROM AUTHOR]

Based on the structure–activity relationship of etoxazole analogues and benzoylphenylureas, a series of 2-(2,6-difluorophenyl)-4-(4-substitutedphenyl)-1,3-oxazolines 4a–y were designed and synthesized. It was found that most of these compounds showed excellent acaricidal activities. They gave above 85% mortality at a concentration of 2.5 mg L−1, both for the eggs and larvae of spider mites. Some compounds also showed excellent insecticidal activities. The position and type of the substituents on the 4-phenyl of 2,4-diphenyl-1,3-oxazoline have a great influence on the activities. 2-(2,6-Difluorophenyl)-4-(2-Cl-4-(4-Cl-phenoxy)phenyl)-1,3-oxazoline (4r) exhibited 100% acaricidal mortality at 2.5 mg L−1, with 65% and 93% mortality against beet armyworm and diamondback moth, respectively, at 12.5 mg L−1, which is almost the same level as etoxazole. The newly found structure–activity relationship may also benefit further acaricide/insecticide development. [ABSTRACT FROM AUTHOR]