Organic Reactions in Ionic Liquids: Ionic Liquid Ethylammonium Nitrate–Promoted Knoevenagel Condensation of Meldrum's Acid With Aromatic Aldehydes

The Knoevenagel condensation of Meldrum's acid with aromatic aldehydes proceeded efficiently in a reusable ionic liquid, ethylammonium nitrate, at room temperature in the absence of any catalyst with high yields.     

Noncovalent Functionalization of Multiwalled Carbon Nanotubes by Anionic Polymer Poly(Sodium 4‐Styrenesulfonate) in Water

We have found that polymer poly (sodium 4‐styrenesulfonate) (PSS) is a facile and effective polymer to assist in the dispersion of MWCNTs in aqueous solutions. With the increase of the concentration of PSS solutions, the dispersibility of MWCNTs in PSS solution increases. Cast films of MWCNTs/PSS (2 wt.%) on GC electrode show a typical redox couple at scan rate of 1 V/s in phosphate buffer solution, indicating good electrical conductivity.     

Surface Performance and Cytocompatibility Evaluation of Acrylic Acid-Mediated Carboxymethyl Chitosan Coating on Poly(tetrafluoroethylene-co-hexafluoropropylene)

To improve the biocompatibility of poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) film, a technique based on Ar plasma pretreatment and UV-induced grafting polymerization was used to immobilize carboxymethyl chitosan (CMCS) on the FEP film surfaces. Initially Ar plasma was used to treat FEP film. Then, plasma treated FEP film was modified via UV-induced grafting polymerization with hydrophilic acrylic acid (AAc) monomer. The following immobilization of CMCS on the FEP-pAAc surface was carried out via an amidation reaction. The change of chemical composition and surface morphology of FEP film were characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), scanning electronic microscopy (SEM) and atomic force microscopy (AFM). Results of water contact angles measurement showed that the hydrophilicity of the surface has improved significantly after surface modification. Furthermore, methyl thiazolyl tetrazolium (MTT) assay and cell morphology analysis confirmed that mouse fibroblasts (L929 cells) attachment and proliferation were improved remarkably on the modified FEP surface. These results suggest that CMCS were successfully employed to surface engineering FEP film, and enhanced its cell biocompatibility. The approach presented here may be exploited for surface modification of biomaterials.     

Synthesis,Characterization and Biological Evaluation of Two Silver(I) trans‐Cinnamate Complexes as Urease Inhibitors

Two new silver(I) trans‐cinnamates, namely [Ag(2‐cca)(H₂O)]₂ ( 1 ) and [Ag(4‐cca)]_n ( 2 ) (2‐ccaH = 2‐chlorocinnamic acid and 4‐ccaH = 4‐chlorocinnamic acid), were synthesized and structurally characterized. Single crystal X‐ray studies reveal that each silver(I) atom in 1 is two‐coordinate by a 2‐chlorocinnamate ligand and one water molecule to afford a discrete centrosymmetric dimer with the ligand‐unsupported Ag···Ag interactions (3.218(4) Å), while a pair of symmetry‐related silver(I) atoms in 2 are clamped by two μ₂‐η¹:η¹ 4‐chlorocinnamate ligands to yield a binuclear silver(I) moiety incorporating a ligand‐supported Ag···Ag interaction (2.819(5) Å). Both complexes 1 and 2 show potent urease inhibitory activities with the respective IC₅₀ values of 0.66 and 1.10 μM.     

Highly selective trifluoroacetic ester/ketone metathesis: an efficient approach to trifluoromethyl ketones and esters

A highly selective and atom efficient ‘trifluoroacetic ester/ketone metathesis’ has been sincerely witnessed. Enolizable alkyl (at least two non-hydrogen atoms) aryl ketones were found to react readily with ethyl trifluoroacetate under the promotion of NaH to afford trifluoroacetic ester/ketone exchange products, trifluoromethyl ketones (TFMKs), and aromatic acid esters, which were quite different from the general Claisen condensation products, 1,3-diketones. The outcome of the reaction between ketone and ethyl trifluoroacetate is strongly related to the structures of substrates, the steric congestion caused by alkyl group is in favor of the C–C bond cleavage. DFT investigation further disclosed that the metathesis reaction was a kinetically favored pathway. Using only a slight excess of cheap trifluoromethylation reagent, simple operation and mild conditions make it a practical method for preparation of TFMKs on large scale, as well as a new choice of converting aryl alkyl ketones to aromatic acid esters.     

Revisit of a series of ICT fluorophores: skeletal characterization,structural modification,and spectroscopic behavior

We have revisited the synthesis of a series of ICT fluorophores, which were reported to have a core structure of 8-oxo-8H-acenaphtho[1,2-b]pyrrol-9-carbonitrile. However, based on the 2D NMR and X-ray diffraction analysis, their core structure was corrected as 1-oxo-1H-phenalene-2,3-dicarbonitrile (1). Compound 1 shows a highly electron-deficient nature and can easily undergo oxidative S_NAr^H reaction on the naphthyl ring to produce a series of novel ICT fluorophores. The regioselectivity of this substitution reaction was studied by introduction of representative nucleophiles. Moreover, due to the strong rigidity and efficient ICT nature, the obtained fluorescent dyes display very good spectroscopic properties even in an aqueous environment.     

A simple and economic method for accurate determination of the energy peak efficiency of 208 keV γ-ray of 237U based on 241Pu/237U secular equilibrium

A new method is developed for the determination of energy peak efficiency of 208 keV γ-ray of ²³⁷U based on ²⁴¹Pu/²³⁷U secular equilibrium. Plutonium solution was purified to remove Am with Dowex 1 × 2 anion exchange chromatography and the concentration of ²⁴¹Pu in the purified solution was determined using ²⁴²Pu isotope-dilution mass spectrometry on an inductively-coupled plasma mass spectrometry. The solution can be used as calibration source for the determination of energy peak efficiency of 208 keV γ-ray of ²³⁷U after 48 days. The method was validated for a planar HPGe detector at the 12 mm above the detector surface. The results showed that this is a simple and economic method for determining the energy peak efficiency of gamma detectors for 208 keV γ-ray of ²³⁷U.     

Harmonically trapped quasi-two-dimensional Fermi gases with synthetic spin-orbit coupling

We study the properties of spin-orbit coupled and harmonically trapped quasi-two-dimensional Fermi gas with tunable s-wave interaction between the two spin species. We adapt an effective two-channel model which takes the excited states occupation in the strongly confined axial direction into consideration by introducing dressed molecules in the closed channel, and use a Bogoliubovde Gennes (BdG) formalism to go beyond local density approximation. We find that both the in-trap phase structure and density distribution can be significantly modified near a wide Feshbach resonance compared with the single-channel model without the dressed molecules. Our findings will be helpful for the experimental search for the topological superfluid phase in ultracold Fermi gases.     

Fiber-optic beam shaper based on multimode interference

A new method of fiber-optic based beam shaping is investigated both numerically and experimentally. A cylindrically symmetric method of lines (MoLs) is developed to simulate the device. The device is fabricated by fusion splicing a predetermined length of multimode fiber (MMF) to a single-mode fiber. The multimode interference (MMI) effects create ring-shaped field profiles at certain positions inside the MMF. The shaped beam can be used in medical applications requiring particular irradiation patterns.