We have recently identified a new class of filamenting temperature-sensitive mutant Z (FtsZ)-interacting compounds that possess a 2,4,6-trisubstituted pyrimidine–quinuclidine scaffold with moderate antibacterial activity. Employing this scaffold as a molecular template, a compound library of amine-linked 2,4,6-trisubstituted pyrimidines with 99 candidates was successfully established by employing an efficient convergent synthesis designed to explore their structure–activity relationship. The results of minimum inhibitory concentration (MIC) assay against Staphylococcus aureus strains and cytotoxicity assay against the mouse L929 cell line identified those compounds with potent antistaphylococcal properties (MIC ranges from 3 to 8 μg/mL) and some extent of cytotoxicity against normal cells (IC50 ranges from 6 to 27 μM). Importantly, three compounds also exhibited potent antibacterial activities against nine clinically isolated methicillin-resistant S. aureus (MRSA) strains. One of the compounds, 14av_amine16, exhibited low spontaneous frequency of resistance, low toxicity against Galleria mellonella larvae, and the ability to rescue G. mellonella larvae (20% survival rate at a dosage of 100 mg/kg) infected with a lethal dose of MRSA ATCC 43300 strain. Biological characterization of compound 14av_amine16 by saturation transfer difference NMR, light scattering assay, and guanosine triphosphatase hydrolysis assay with purified S. aureus FtsZ protein verified that it interacted with the FtsZ protein. Such a property of FtsZ inhibitors was further confirmed by observing iconic filamentous cell phenotype and mislocalization of the Z-ring formation of Bacillus subtilis. Taken together, these 2,4,6-trisubstituted pyrimidine derivatives represent a novel scaffold of S. aureus FtsZ inhibitors.Topics: Biological and Medicinal chemistry; Mechanical properties; Organic compounds and Functional groups; Proteins; Structure-activity relationship; Structure-activity relationship;

The filamenting temperature-sensitive mutant Z (FtsZ) protein is generally recognized as a promising antimicrobial drug target. In the present study, a small organic molecule (tiplaxtinin) was identified for the first time as an excellent cell division inhibitor by using a cell-based screening approach from a library with 250 compounds. Tiplaxtinin possesses potent antibacterial activity against Gram-positive pathogens. Both in vitro and in vivo results reveal that the compound is able to disrupt dynamic assembly of FtsZ and Z-ring formation effectively through the mechanism of stimulating FtsZ polymerization and impairing GTPase activity.

•The synthesis routes, surface structure and properties of MXenes are illustrated.•The MXenes towards electrocatalysis and photocatalysis applications are reviewed.•MXenes as promising candidates in sensing are underlined in this review.•MXenes as ideal adsorbents are highlighted.MXenes, a new, very recently emerging family of two-dimensional (2D) early transition metal carbides and/or nitrides, has attracted a great influence in the fields of physics, material science, chemistry, and nanotechnology. In this review, their synthesis, compelling physical, chemical, as well as their various potential applications in catalysis, sensors and adsorption are highlighted. First, the synthesis, structural variety, and chemical and physical properties are summarized. Then the electroactivity, durability, ease of functionalization of MXenes toward electrocatalysis and photocatalysis applications are introduced. The specific properties of metallic conductivity, biocompatibility, hydrophilic surface, and 2D layered atomic structure that make MXenes promising candidates in sensing of rapid, easy, and label-free detection are consequently discussed. Finally, how MXenes could be considered as ideal adsorbents due to the advantages of large surface area and abundant active sites is underlined. Promising theoretical calculations and first remarkable performances in these applications are also highlighted.

Carbon-based electrodes have been widely used in electroanalysis for more than half a century, but the factors governing the heterogeneous electron-transfer (HET) rate are still unclear. The effects of the exposed edge plane site density, inherent resistance of the carbon electrode, and adjustable resistors on the HET kinetics of several outer- and inner-sphere redox couples including [Fe(CN)6]3–/4–, Ru(NH3)63+/2+, Fe3+/2+, dopamine, ascorbic acid, and uric acid are investigated using three kinds of carbon electrodes composed of core–shell quasi-aligned nanofiber arrays (QANFAs). The internal resistance is found to be a key factor affecting the HET kinetics and electrochemical biosensing properties. The electrodes exhibit high selectivity and sensitivity in dopamine detection in the presence of ascorbic acid and uric acid. In addition to the promising application to electrochemical biosensing, the core–shell TiC/C QANFAs encompassing a highly electroactive carbon shell and conductive TiC core provide insights into the design and construction of the ideal carbon electrode.Keywords: carbon electrode; core−shell nanofiber; dopamine; electrochemical biosensor; electron transfer kinetics

A highly sensitive non-enzymatic glucose sensor based on Cu nanoparticles (CuNPs)/polyaniline (PANI)/graphene nanocomposite was fabricated via simple in-situ reduction of Cu precursor in polyaniline nanofibers under mild conditions followed by mechanical mixing with graphene suspension to form the composites with different graphene contents (0.5%, 1%, and 2%). The properties of nanocomposites were characterized by SEM, TEM, XRD, UV–Vis, and XPS. The CuNPs (d = 2–4 nm) only slightly altered the ordered structure of PANI. It was found that CuNPs have direct electronic interaction with PANI via the N atoms on the polymer backbone, which enabled fast electrons transfer from electrode to CuNPs through graphene and PANI. The CuNPs/PANI/graphene nanocomposites were coated on a glassy carbon electrode for the investigation of their electrochemical properties. Both CuNPs/PANI and CuNPs/PANI/graphene showed high sensitivity towards glucose oxidation which occurred at ~ 0.5 V vs. SCE. The best performance was achieved by the CuNPs/PANI/1% graphene-modified electrode which showed sensitivity of ~ 150 mA cm− 2 M− 1, detection limit of 0.27 μM (S/N = 3), and response time of about 3 s. This system was also highly selective towards glucose oxidation that almost no signal was detected from interferents such as ascorbic acid and dopamine, demonstrating its great potential as a non-enzymatic glucose sensor.

•Hierarchical VC nanoparticles embedded in carbon network nanosheets are prepared.•The electrocatalyst boasts highly efficient HER activity.•The electrocatalyst shows a small tafel slope with extremely low overpotential.•The electrocatalyst exhibits outstanding durability in acidic media.A hierarchical nanosheet structure comprising isolated vanadium carbide nanoparticles encapsulated in a highly conductive mesoporous graphitic carbon network (VC-NS) is synthesized by a hydrothermal reaction and subsequent low-temperature magnesium thermic reaction. It has a large specific surface area and boasts highly efficient HER (hydrogen evolution reaction) activity such as very small overpotential, fast proton discharge kinetics, and excellent durability. The small Tafel slope of 56 mV dec−1 with a low overpotential of only 98 mV at 10 mA cm−2 is quite close to that of the commercial 20% Pt/C catalyst. The excellent durability is indicated by the overpotential shift of only 10 mV after 10000 cyclic voltammetric cycles at a current density of 80 mA cm−2. The high-performance precious-metal-free electrocatalyst is promising in HER and related energy generation applications.Hierarchical vanadium carbide nanosheets are synthesized by a low-temperature magnesium thermic reaction using V2O5 nanosheets as both the template and precursor to produce a highly active and long life time hydrogen evolution reaction electrocatalyst.

Copper-based chalcogenides of earth-abundant elements have recently arisen as an alternate material for solar energy conversion. Cu2FeSnS4 (CITS), a quaternary chalcogenide that has received relatively little attention, has the potential to be developed into a low-cost and environmentlly friendly material for photovoltaics and photocatalysis. Herein, we report, for the first time, the synthesis, characterization, and growth mechanism of novel Au/CITS core–shell nanostructures with controllable morphology. Precise manipulations in the core–shell dimensions are demonstrated to yield two distinct heterostructures with spherical and multipod gold nanoparticle (NP) cores (Ausp/CITS and Aump/CITS). In photocatalytic hydrogen generation with as-synthesized Au/CITS NPs, the presence of Au cores inside the CITS shell resulted in higher hydrogen generation rates, which can be attributed to the surface plasmon resonance (SPR) effect. The Ausp/CITS and Aump/CITS core–shell NPs enhanced the photocatalytic hydrogen generation by about 125% and 240%, respectively, compared to bare CITS NPs.Keywords: anisotropic growth; Au/CITS core−shell; hydrogen evolution; photocatalysis; surface plasmon resonance;

Filamenting temperature-sensitive mutant Z (FtsZ) is an essential cell division protein that cooperates in the formation of the cytokinetic Z-ring in most bacteria and has thus been recognized as a promising antimicrobial drug target. We have recently used a structure-based virtual screening approach to identify pyrimidine-linked quinuclidines as a novel class of FtsZ inhibitors. In this study, we further investigated the antibacterial properties of one of the most potent compounds (quinuclidine 1) and its synergistic activity with β-lactam antibiotics. Susceptibility results showed that quinuclidine 1 was active against multiple antibiotic-resistant bacterial strains including methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium with minimal inhibitory concentrations of 24 μg ml−1. When quinuclidine 1 was combined with β-lactam antibiotics, synergistic antimicrobial activities against antibiotic-resistant strains of S. aureus were found. Further in vitro studies suggest that prevention of FtsZ protofilament formation by quinuclidine 1 impairs the formation of Z-ring, and thus inhibits bacterial division. These findings open a new approach for development of quinuclidine-based FtsZ inhibitors into potent antimicrobial agents.

A dinuclear ruthenium catalyst with a rigid anthracene spacer shows excellent regio- and stereo-selectivity in the atom-economic addition of aliphatic carboxylic acids to phenylacetylene, producing exclusively anti-Markovnikov enol-esters with high E/Z ratios of the isomers.

•Vertically oriented graphene sheets are prepared on graphite by anodic exfoliation.•The structure facilitates transportation of ions and utilization of graphene.•The graphene sheets have very large areal and volumetric capacitances.•This strategy is promising in the development of integrated energy storage devices.Vertically oriented graphene nanosheets (VOGNs) fabricated on conductive substrates with a large amount of edge planes and open channels are ideal for electrochemical double-layer (EDL) capacitor electrodes. However, preparation of such a structure with high-density of graphene nanosheets is challenging. Herein, a facile, environment-friendly, and economical technique to prepare high-quality VOGNs directly on conductive graphite plates with a high mass loading is described. The VOGNs are obtained by electrochemical anodization of graphite and a large amount of aligned reduced graphene oxide (rGO) is produced and adheres strongly to the graphite substrate (G@rGO). The symmetrical supercapacitors composed of the G@rGO electrodes exhibit a high volumetric capacitance of 3.9 F cm−3 and energy density of 0.66 Wh L−1 (based on the volume of the whole electrode) at a current density of 7.5 mA cm−3 in 6 M KOH. The rate performance and long-term cycling stability are very good. The outstanding capacitive performance can be attributed to the unique structure of the G@rGO electrode which facilitates transportation of ions between the electrolyte and graphene surface, minimizes the distributive nature of charge storage, expedites the formation of EDL, and enhances the electrochemical utilization of graphene and stability by avoiding restacking and aggregation of graphene nanosheets.A facile and efficient technique for the preparation of high-density and vertically oriented graphene nanosheets (VOGNs) directly on graphite plates is described. The VOGNs are obtained by electrochemical anodization of graphite producing aligned graphene oxide (G@GO) that adheres strongly to the graphite substrate (G@rGO) and reduction. The integrated supercapacitors composed of the G@rGO electrodes boast excellent rate performance and long-term cycling stability such as high volumetric capacitance of 3.9 F cm−3 in 6 M KOH.

•An environmentally benign ionic liquid system for carbon dioxide fixation.•Addition of carbon dioxide to non-polar aliphatic epoxides under mild reaction conditions.•Relatively mild CO2 pressure and low temperature.•Convenient recycling and reuse of the medium.A mixed ionic liquid system has been developed for the efficient catalysis of CO2 addition to aliphatic epoxides without involving any transition metal catalysts or other additives. The ionic liquid integrated with pyridinium and pyrrolidinium groups (1·(Br)3) together with a non-polar ionic liquid (3·(Ntf)2) effectively transformed non-polar aliphatic epoxides to cyclic carbonates by the reaction with CO2 under mild CO2 pressure (3.0 MPa) and reaction temperature (80 °C). The presence of 3·(Ntf)2 remarkably improved the catalytic activity of 1·(Br)3 towards non-polar epoxides by increasing the miscibility of catalyst with the substrates. The mixed ionic liquid system is robust enough to be recycled without any significant loss of catalytic activity. GC–MS studies were performed to reveal the reaction pathways to the cyclic carbonates and a feasible model accounting for the effective CO2 activation in the ionic liquid system was proposed using density functional theory (DFT) calculations.

A dinuclear ruthenium catalyst with a rigid anthracene spacer shows excellent regio- and stereo-selectivity in the atom-economic addition of aliphatic carboxylic acids to phenylacetylene, producing exclusively anti-Markovnikov enol-esters with high E/Z ratios of the isomers.