Fluorescent sensor based on dimesitylborylthiophene derivative for probing fluoride and cyanide

A new D-π-A dimesitylboron derivative with terminal phenothiazine bridged by fluorenevinyl (PFTB) has been synthesized. It was found that PFTB could selectively recognize fluoride and cyanide anions by naked eyes. Upon addition of F⁻ and CN⁻, the color of the solution of PFTB in DCM turned to yellowish-green from yellow and strong green emitting was observed under UV light, while the emission of PFTB in DCM was weak. Moreover, the presence of 10 equiv of tetrabutylammonium salts of other anions, such as Cl⁻, Br⁻, I⁻, AcO⁻, HSO₄⁻, H₂PO₄⁻, could not lead to obvious changes of the UV–vis absorption and the fluorescent emission spectra of PFTB. The detection limits of PFTB towards F⁻ and CN⁻ were 7.52×10⁻⁸ mol/L and 6.12×10⁻⁸ mol/L in DCM, respectively. Therefore, the D-π-A type triarylborane derivatives can be used as ‘turn on’ fluorescent sensors for detecting F⁻ and CN⁻.     

Synthesis of N-labeled 4-oxo-2,2,6,6-tetraethylpiperidine nitroxide for EPR brain imaging

A scalable synthetic route for ¹⁵N-labeled 4-oxo-2,2,6,6-tetraethylpiperidine nitroxide (¹⁵N-TEEPONE) is described. This ¹⁵N-labeled nitroxide is suitable for electron paramagnetic resonance imaging of brain, and its higher sensitivity compared with that of its ¹⁴N-counterpart is an important advantage of the labeled derivative.     

Two novel polycyclic spiro lignans from Gymnotheca involucrata

Two novel lignans, gymnothespirolignans A (1) and B (2), possessing a rare polycyclic spiro skeleton, were isolated from the endemic plant of Gymnotheca involucrata Pei. Their structures were determined by spectroscopic evidences and the absolute configurations were confirmed by single crystal X-ray diffraction analysis. Compounds 1 and 2 showed promising antiviral activities against RSV with an IC₅₀ value of 31.87 and 17.51 μM, respectively.     

Phosphine-mediated synthesis of trifluoromethyl substituted pyrroles using TFAA as the CF3 source

A phosphine-mediated synthesis of trifluoromethyl substituted pyrrole derivatives was achieved. The method described here is very fast, operationally simple, and easily amenable to scale-up, and commercially available trifluoroacetic anhydride (TFAA) is used as the only trifluoromethyl source. A wide range of products were obtained with good yields under mild condition using this method.     

A green strategy for lithium isotopes separation by using mesoporous silica materials doped with ionic liquids and benzo-15-crown-5

Three new mesoporous silica materials IL15SGs (HF15SG, TF15SG and DF15SG) doped with benzo-15-crown-5 and imidazolium based ionic liquids (C₈mim⁺PF₆ ^?, C₈mim⁺BF₄ ^? or C₈mim⁺NTf ₂ ^? ) have been prepared by a simple approach to separating lithium isotopes. The formed mesoporous structures of silica gels have been confirmed by transmission electron microscopy image and N₂ gas adsorption–desorption isotherm. Imidazolium ionic liquids acted as templates to prepare mesoporous materials, additives to stabilize extractant within silica gel, and synergetic agents to separate the lithium isotopes. Factors such as lithium salt concentration, initial pH, counter anion of lithium salt, extraction time, and temperature on the lithium isotopes separation were examined. Under optimized conditions, the extraction efficiency of HF15SG, TF15SG and DF15SG were found to be 11.43, 10.59 and 13.07 %, respectively. The heavier isotope ⁷Li was concentrated in the solution phase while the lighter isotope ⁶Li was enriched in the gel phase. The solid–liquid extraction maximum single-stage isotopes separation factor of ⁶Li–⁷Li in the solid–liquid extraction was up to 1.046 ± 0.002. X-ray crystal structure analysis indicated that the lithium salt was extracted into the solid phase with crown ether forming [(Li_0.5)₂(B15)₂(H₂O)]⁺ complexes. IL15SGs were also easily regenerated by stripping with 20 mmol L^?1 HCl and reused in the consecutive removal of lithium ion in five cycles.     

2,6,6-三甲基-双环[3,1,1]庚基-3-(4-芳基-2-噻唑)腙类化合物的合成及其抑菌和抗肿瘤活性研究

以α-蒎烯为起始原料,经加成、氧化、缩合制得中间体,继而与α-溴代芳基乙酮在常温下反应合成12个新型2,6,6-三甲基-双环[3,1,1]庚基-3-(4-芳基-2-噻唑)腙类化合物,产率达52.4%~88.9%.其结构经1H NMR,13C NMR,IR,LC/MS和元素分析进行了确证.初步生物活性测试结果表明:部分目标化合物具有较好的抑菌活性和一定的抗肿瘤活性.     

Construction of a portable sample preparation device with a magnetic poly(methacrylic acid‐co‐ethylene dimethacrylate) monolith as the extraction medium and its application in the enrichment of UV filters in water samples

A portable sample preparation device with a magnetic polymer monolith as the extraction medium was constructed. The monolith was synthesized by polymerizing methacrylic acid and ethylene dimethacrylate around a cylindrical magnet. In this way, the monolith with a magnetic core could be readily attached to the extraction device by magnetism. The constructed device was evaluated for the enrichment of UV filters in water samples, followed by high‐performance liquid chromatographic analysis. The extraction efficiency for the targets was satisfactory with no matrix interference. Good linearities were obtained for the UV filters with the correlation coefficients >0.9986. The limits of detection and quantification for the UV filters were 0.3–0.8 and 1.0–2.4 ng/mL, respectively. The recoveries of the UV filters from the spiked water samples at the concentration of 100 ng/mL were 95.3–101.7%, with relative standard deviations <10%. Accordingly, the proposed portable device was demonstrated to be suitable for on‐site simultaneous sampling, purification, and preconcentration within a single step.     

Computer‐assisted design and synthesis of molecularly imprinted polymers for the simultaneous determination of six carbamate pesticides from environmental water

The computer‐assisted design and synthesis of molecularly imprinted polymers for the simultaneous capture of six carbamate pesticides from environmental water are reported in this work. The quantum mechanical computational approach was employed to design the molecularly imprinted polymers with carbofuran as template. The interaction energies between the template molecule and different functional monomers in various solvents were calculated to assist in the selection of the functional monomer and porogen. The optimised molecularly imprinted polymer was subsequently used as a class‐selective sorbent in solid‐phase extraction for pre‐concentration and determination of carbamates from environmental water. The parameters influencing the extraction efficiency of the molecularly imprinted solid‐phase extraction procedure were systematically investigated to facilitate the class‐selective extraction. For the proposed method, linearity was observed over the range of 2–500 ng/mL with the correlation coefficient ranging from 0.9760 to 1.000. The limits of detection ranged from 0.2 to 1.2 ng/mL, and the limit of quantification was 4 ng/mL. These results confirm that computer‐assisted design is an effective evaluation tool for molecularly imprinted polymers synthesis, and that molecularly imprinted solid‐phase extraction can be applied to the simultaneous analysis of carbamates in environmental water.