A Novel and Efficient Reaction of Imidazolidin-2-one and N-Acylbenzotriazoles: A Facile Synthesis of 1-Acylimidazolidin-2-one

Acylation of imidazolidin-2-one with readily available N-acylbenzotriazoles, in the presence of K₂CO₃, produced 1-acylimidazolidin-2-ones and N,N′-diacyl-imidazolidin-2-one in moderate to good yields. The utilization of N-acylbenzotriazoles which make the reaction simple and mild, may be especially advantageous when the corresponding acid chlorides are not stable or not easily prepared. It's also an example of the reaction of N-acylbenzotriazoles and amide.     

Mutation effects of neuraminidases and their docking with ligands: a molecular dynamics and free energy calculation study

A systematic study has been performed on neuraminidase (NA) mutations and NA-inhibitor docked complexes, with the aim to understand protein–ligand interactions and design broad-spectrum antiviral drugs with minimal resistances. The catalytic D151 residue is likely to mutate while others are relatively conserved. The NA active-site conformations are altered by mutations, but more alterations do not necessarily result in larger deviations to the binding properties. The effects of all related mutations have been discussed; e.g., for the arginine triad (R118, R292 and R371), it is found that residue R118 plays the most significant role during ligand binding. Generally, the calculated binding free energies agree well with the experimental observations. Susceptibility of influenza virus to NA inhibitors can be reinforced by some mutations; e.g., the binding free energies of ligands with N2 subtype increase from ?18.0 to ?42.1 kcal mol^?1 by the E119D mutation. Mutations of the various NA subtypes often cause similar conformational and binding changes, explaining the occurrence of cross resistances; nonetheless, differences can be detected in some cases that correspond to subtype-specific resistances. For all NA subtypes, the electrostatic contributions are the major driving force for ligand binding and largely responsible for the binding differences between the wild-type and mutated NA proteins.     

Raman spectra of proton order of thin ice Ih film

The polarized Raman spectra of the upper part of a thin ice Ih film were obtained in the range of 150 cm⁻¹ to 3800 cm⁻¹. The spectra showed clear polarization dependence; several new peaks were also observed. The longitudinaloptic–tranverseoptic (LO–TO) splitting of the mode near 220 cm⁻¹ in the translational vibration region was experimentally confirmed at 133 K. The Fermi resonance between the bending overtone (around 3270 cm⁻¹) and symmetry stretching fundamental (around 3350 cm⁻¹) in the stretching vibration region appeared at nearly the same temperature. Results showed that ice XI (i.e. proton‐ordered phase of ice Ih) slowly formed in the upper part of a thin ice Ih film without KOH as the temperature gradually decreased below 133 K. Copyright © 2015 John Wiley & Sons, Ltd.     

Zeolitic imidazolate framework-8 as a dispersive solid phase extraction sorbent for simultaneous determination of 145 pesticide residues in polyphenol-rich plants

Many plants have a high polyphenol content, which causes the matrix effect and makes the analysis of trace pesticide residues highly challenging. A common approach to improving matrix effects is to purify pesticides through the use of sorbents, but this requires a combination of multiple sorbents and extensive use. Zeolitic imidazolate framework-8 is widely used for pesticide analysis due to its high porosity, large specific surface area, and versatility. Here, we established and validated a modified quick, easy, cheap, effective, rugged, and safe method based on a zeolitic imidazolate framework-8 that was used to test the removal ability for polyphenols. To this end, 145 pesticide residues in peppermint, perilla, fennel, and mulberry leaves were analyzed by the modified method coupled with liquid chromatography with tandem mass spectrometry. The mean recoveries of all pesticide residues were in the range of 74.3–103.7%, with mean relative standard deviations ≤9.1% at spiked concentrations of 1, 10, 50, and 100 μg/kg for mulberry leaves. The limits of quantitation of the method ranged from 1 to 50 μg/kg. This study offers a reliable approach for the accurate quantitative analysis of various trace substances in the polyphenol-rich plants.     

Donor-Acceptor Typed AIE Luminogens with Near-infrared Emission for Super-resolution Imaging

Aggregation-induced emission(AIE)luminogens(AIEgens)with high brightness in aggregates exhibit great potentials in biological imaging,but these AIEgens are seldom applied in super-resolution biological imaging,especially in the imaging by using the structural illumination microscope(SIM).Based on this consideration,we synthesized the donor-acceptor typed AIEgen of DTPA-BTN,which not only owns high brightness in the near-infrared(NIR)emission region from 600 nm to 1000 nm(photoluminescence quantum yield,PLQYs=11.35%),but also displays excellent photo-stability.In addition,AIE nanoparticles based on 4,7-ditriphenylamine-[1,2,5]-thiadiazolo[3,4-c]pyridine(DTPA-BTN)were also prepared with highly emissive features and excellent biocompatibility.Finally,the developed DTPA-BTN-based AIE nanoparticles were applied in the super-resolution cellular imaging via SIM,where much smaller full width at half-maximum values and high signal to noise ratios were obtained,indicating the superior imaging resolution.The results here imply that highly emissive AIEgens or AIE nanoparticles can be promising imaging agents for super-resolution imaging via SIM.     

Large Hexagonal Bi‐ and Trilayer Graphene Single Crystals with Varied Interlayer Rotations

Bi‐ and trilayer graphene have attracted intensive interest due to their rich electronic and optical properties, which are dependent on interlayer rotations. However, the synthesis of high‐quality large‐size bi‐ and trilayer graphene single crystals still remains a challenge. Here, the synthesis of 100 μm pyramid‐like hexagonal bi‐ and trilayer graphene single‐crystal domains on Cu foils using chemical vapor deposition is reported. The as‐produced graphene domains show almost exclusively either 0° or 30° interlayer rotations. Raman spectroscopy, transmission electron microscopy, and Fourier‐transformed infrared spectroscopy were used to demonstrate that bilayer graphene domains with 0° interlayer stacking angles were Bernal stacked. Based on first‐principle calculations, it is proposed that rotations originate from the graphene nucleation at the Cu step, which explains the origin of the interlayer rotations and agrees well with the experimental observations.     

Chiral Metal–Organic Frameworks Bearing Free Carboxylic Acids for Organocatalyst Encapsulation

Two chiral carboxylic acid functionalized micro‐ and mesoporous metal–organic frameworks (MOFs) are constructed by the stepwise assembly of triple‐stranded heptametallic helicates with six carboxylic acid groups. The mesoporous MOF with permanent porosity functions as a host for encapsulation of an enantiopure organic amine catalyst by combining carboxylic acids and chiral amines in situ through acid–base interactions. The organocatalyst‐loaded framework is shown to be an efficient and recyclable heterogeneous catalyst for the asymmetric direct aldol reactions with significantly enhanced stereoselectivity in relative to the homogeneous organocatalyst.     

Design Strategies for High-Performance Aqueous Zn/Organic Batteries

Organic electroactive compounds are attractive to serve as the cathode materials of aqueous zinc-ion batteries (ZIBs) because of their resource renewability, environmentally friendliness and structural diversity. Up to now, various organic electrode materials have been developed and different redox mechanisms are observed in aqueous Zn/organic battery systems. In this Minireview, we present the recent developments in the energy storage mechanisms and design of the organic electrode materials of aqueous ZIBs, including carbonyl compounds, imine compounds, conductive polymers, nitronyl nitroxides, organosulfur polymers and triphenylamine derivatives. Furthermore, we highlight the design strategies to improve their electrochemical performance in the aspects of specific capacity, output voltage, cycle life and rate capability. Finally, we discuss the challenges and future perspectives of aqueous Zn/organic batteries.     

Self-Assembly of Highly Stable Zirconium(IV) Coordination Cages with Aggregation Induced Emission Molecular Rotors for Live-Cell Imaging

The self-assembly of highly stable zirconium(IV)-based coordination cages with aggregation induced emission (AIE) molecular rotors for in vitro bio-imaging is reported. The two coordination cages, NUS-100 and NUS-101, are assembled from the highly stable trinuclear zirconium vertices and two flexible carboxyl-decorated tetraphenylethylene (TPE) spacers. Extensive experimental and theoretical results show that the emissive intensity of the coordination cages can be controlled by restricting the dynamics of AIE-active molecular rotors though multiple external stimuli. Because the two coordination cages have excellent chemical stability in aqueous solutions (pH stability: 2–10) and impressive AIE characteristics contributed by the molecular rotors, they can be employed as novel biological fluorescent probes for in vitro live-cell imaging.