Latest ArticlesWe report the synthesis and characterization of a fan-shaped chiral nanographene 1, which is composed of 6 hexabenzocoronene subunits with 216 conjugated carbon atoms. In the dehydrocyclization reaction, 38 CC bonds are formed simultaneously. 1 exhibits strong panchromatic absorption from the ultraviolet to the near-infrared, with an absorption coefficient of 209,000 L mol−1 cm−1 at 564 nm. Optically pure samples, obtained via chiral HPLC, show distinct ECD signals (|Δε| = 704 L mol−1 cm−1 at 405 nm). Upon excitation, 1 emits near-infrared fluorescence at 820 nm with a quantum yield of 5.5%. These photophysical properties of 1 were analyzed with the assistance of DFT calculations.
Waste generation from food manufacturing facilities poses a serious hazard like environmental degradation, water pollution, and land pollution due to its high nutrient composition. Specifically, solid waste (powder) disposal requires additional energy sources in terms of scientific treatment, structured collection, and disposal packaging according to the safety regulation. Thus, this research discusses the viewpoint of integrating food processing waste as an organic carbon source with BG-11 medium for Chlorella vulgaris (FSP-E) growth. The food processing waste powders investigated in this study were obtained from milk, and biscuit manufacturing facilities. The culture medium was modified by combining both BG-11 and food processing waste powders to identify the optimal algal growth and biochemical content. Compared to the microalgae grown in BG-11 alone (IBG), the combination of biscuit waste and IBG produced higher biomass concentration (44%), with increased lipid (11%), protein (20%), and carbohydrate (57%) contents. Chlorella vulgaris was able to uptake nutrients from the culture medium with combination of food processing waste and IBG thus enhancing its growth. The results obtained also indicate that an integrated culture system using food processing waste and synthetic sources can generate energy out of waste by improving the bio-composition of the microalgae biomass.
Dinitrogen activation under mild conditions is important but extremely challenging due to the inert nature of the N≡N triple bond evidenced by high bond dissociation energy (945 kJ/mol) and large HOMO-LUMO gap (10.8 eV). In comparison with largely developed transition metal systems, the reported main group species on dinitrogen activation are rare. Here, we carry out density functional theory calculations on methyleneboranes to understand the reaction mechanisms of their dinitrogen activation. It is found that the methyleneboranes without any substituent at the boron atom performs best on dinitrogen activation, which could be contributed to its small singlet-triplet gap. In addition, strong correlations are achieved on dinitrogen activation between the singlet-triplet energy gap and the reaction energies for the formation of the end-on products as well as the side-on ones. The principal interacting orbital analysis suggests that methyleneboranes can mimic transition metals to cleave the NN triple bond. Our findings could be helpful for experimental chemists aiming at dinitrogen activation by main group species.
Aqueous zinc-ion batteries (AZIBs) have aroused significant research interest around the world in the past decade. The use of low-cost aqueous electrolytes and a metallic Zn anode with a suitable redox potential and high energy density make AZIBs a potential alternative to commercial Li-ion batteries in the development of next-generation batteries. However, owing to the narrow electrochemical stability window (ESW) of aqueous electrolytes, the choice of cathode materials is limited, because of which AZIBs exhibit a relatively low operating voltage and energy density. Hence, expanding the ESW of aqueous electrolytes is important for the development of practical AZIBs. This paper systematically reviews the electrolyte engineering strategies being explored to broaden the ESW of AZIBs. An in-depth analysis of high-voltage AZIBs is also presented. We suggest that the realization of high-voltage AZIBs depends on the synergistic development of suitable electrolytes and cathode materials. In addition, the cost associated with their fabrication as well as the use of standardized electrochemical tests should be considered during the design of high-voltage AZIBs.
Hierarchical carbon material is used as a star cocatalyst in the field of photocatalysis due to its excellent catalytic properties. In this work, mesoporous carbon nitride sheet (MCNS) photocatalyst introduced nitrogen-doped hollow carbon spheres assembled with cobalt nanoparticles (Co@NHC) is synthesized by electrostatic adsorption. A series of characterizations are analyzed to display the structures, morphologies and optical properties of as-prepared materials. The photocatalytic activity of Co@NHC/MCNS material is evaluated with hydrogen evolution under visible light irradiation. The results indicate that 5 wt% Co@NHC/MCNS material reveals higher photocatalytic activity of hydrogen evolution rate of 3675 µmol/g with 4 h reaction time, which is 159 times than that of pure MCNS material. The carbon material with excellent charge transport properties can effectively accelerate the charge transfer from ultrathin MCNS to cobalt nanoparticles. The goal of improving the photocatalytic performance of Co@NHC/MCNS material is achieved. As a result, it provides a feasible and promised approach for doping transition metals to enhance photocatalytic activity.
Lithium dendrite growth due to uneven electrodeposition usually leads to the potential hazard of internal short circuit and shorter lifetime of lithium-based batteries. Extensive efforts have been devoted to explore the effects of single or two factors on dendrite growth, involving the diffusion coefficient, exchange current density, electrolyte concentration, temperature, and applied voltage. However, these factors interrelate during battery operation, signifying that a understanding of how they jointly influence the electrodeposition is of paramount importance for the effective suppression of dendrites. Here, we incorporate the dependent relationships among key factors into the phase-field model to capture their synergistic effects on electrodeposition. All the simulations are implemented in our self-written MATLAB code under a unified modeling framework. Following this, five groups of experimentally common dendrite patterns are reproduced and the corresponding electrodeposition driving forces are identified. Unexpectedly, we find that with the decrease of the ratio of exchange current density (or applied voltage) to diffusion coefficient, the electrodeposition morphology changes from needle-like dendrites to columnar dendrites and to uniform deposition. The present phase-field simulation tends to depict the practical electrodeposition process, providing important insights into synergistic regulation to suppress dendrite growth.
The rapid prevalence of antibiotic resistance has led to a significant global health problem. Although colistin is the last resort antibiotic, it is limited by dose dependent toxicity. A critical approach to solve this problem is to use an antibiotic adjuvant, which is able to potentiate the activity of antibiotic and reduce the dosage of antibiotic. Herein, we reported a novel 2-aminothiazoyl piperidine adjuvant, which enhanced the activity of colistin against Acinetobacter baumannii (A. baumannii). Two pilot libraries of 40 compounds were prepared and their adjuvant activities were evaluated. The most potential compound 11j enabled to cause16-fold reduction in the minimum inhibitory concentration (MIC) of colistin at 8 µg/mL. Besides, time-kill curves exhibited that compound 11j had significant adjuvant activity to kill the bacteria. The predicted ADMET analysis showed that 2-aminothiazoyl piperidine derivatives had good drug-likeness and acceptable physicochemical properties. Furthermore, membrane permeability experiments demonstrated that compound 11j was beneficial for colistin to destroy the outer membrane of bacteria. Also, the comparative molecular similarity indices analysis (CoMSIA) and the density functional theory (DFT) calculations were conducted. The results drawn from these analyses indicated that the novel scaffold provided helpful information for the finding of new adjuvant lead.
Macrocycle-based glycoclusters, on account of their promising anti-adhesive properties against bacteria, are potential therapeutic alternatives to classic antibiotics through the much less explored anti-adhesive strategy. In this study, a series of constitutionally-pure pentavalent glycoclusters was prepared by conjugating assorted azido-carbohydrates onto a penta-propargyl rim-differentiated pillar[5]arene (RD-P[5]) scaffold through Cu(I)-catalyzed azide–alkyne cycloaddition "click" reactions. Their binding towards therapeutically relevant bacterial lectins, such as LecA and LecB from Pseudomonas aeruginosa and concanavalin A (ConA), were evaluated subsequently by isothermal titration calorimetric studies. Most of these isomer-free RD-P[5] pentavalent glycoclusters, except the fucosylated ones, display good affinities to lectins. Nonetheless, the dissociation constants observed are similar to those displayed by an analogous pentavalent glycocluster consisting of four P[5] constitutional isomers, in which the RD-P[5] component merely accounts for 7% in the mixture. Our results revealed that high constitutional purity is not essential for achieving effective multivalent interactions between P[5]-based glycoclusters and lectins, presumably as a result of the conformationally labile nature of the P[5] scaffold. This information provides valuable design principles for low-cost and facile syntheses of glycosylated P[5]s for biomedical applications.
A Cu-catalyzed chemoselective heterocyclization of o-cinnamoyl arylisocyanides with α-substituted tosylmethyl isocyanides is developed for the efficient synthesis benzopyrroloazepinones. An isocyanide insertion into the C–Cu bond of organocuprate intermediate is involved for the formation of the seven-membered azepinone ring.
Amyloid proteins correlate with a series of degenerative diseases. Targeting amyloid aggregation has remained a hot topic in therapeutic studies. Numerous inhibitors have been developed, but very few have been approved for marketing. Meanwhile, the growing knowledge of amyloid structural characteristics provides a basis for the rational design of inhibitors. Here we introduce the high-resolution structural findings of amyloid fibrils in recent years and discuss the reported strategies toward rationally designed inhibitors based on amyloid-related structural studies.
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