Vortex‐assisted liquid–liquid microextraction using a low‐toxicity solvent for the determination of five organophosphorus pesticides in water samples by high‐performance liquid chromatography

Vortex‐assisted liquid–liquid microextraction followed by high‐performance liquid chromatography with UV detection was applied to determine Isocarbophos, Parathion‐methyl, Triazophos, Phoxim and Chlorpyrifos‐methyl in water samples. 1‐Bromobutane was used as the extraction solvent, which has a higher density than water and low toxicity. Centrifugation and disperser solvent were not required in this microextraction procedure. The optimum extraction conditions for 15 mL water sample were: pH of the sample solution, 5; volume of the extraction solvent, 80 μL; vortex time, 2 min; salt addition, 0.5 g. Under the optimum conditions, enrichment factors ranging from 196 to 237 and limits of detection below 0.38 μg/L were obtained for the determination of target pesticides in water. Good linearities (r > 0.9992) were obtained within the range of 1–500 μg/L for all the compounds. The relative standard deviations were in the range of 1.62–2.86% and the recoveries of spiked samples ranged from 89.80 to 104.20%. The whole proposed methodology is simple, rapid, sensitive and environmentally friendly for determining traces of organophosphorus pesticides in the water samples.     

One‐dimensional CuII coordination polymers containing C2h‐symmetric 1,1′:4′,1′′‐terphenyl‐3,3′‐dicarboxylate linkers

Two new one‐dimensional Cu^II coordination polymers (CPs) containing the C_2h‐symmetric terphenyl‐based dicarboxylate linker 1,1′:4′,1′′‐terphenyl‐3,3′‐dicarboxylate (3,3′‐TPDC), namely catena‐poly[[bis(dimethylamine‐κN)copper(II)]‐μ‐1,1′:4′,1′′‐terphenyl‐3,3′‐dicarboxylato‐κ⁴O,O′:O′′:O′′′] monohydrate], {[Cu(C₂₀H₁₂O₄)(C₂H₇N)₂]·H₂O}_n, (I), and catena‐poly[[aquabis(dimethylamine‐κN)copper(II)]‐μ‐1,1′:4′,1′′‐terphenyl‐3,3′‐dicarboxylato‐κ²O³:O^3′] monohydrate], {[Cu(C₂₀H₁₂O₄)(C₂H₇N)₂(H₂O)]·H₂O}_n, (II), were both obtained from two different methods of preparation: one reaction was performed in the presence of 1,4‐diazabicyclo[2.2.2]octane (DABCO) as a potential pillar ligand and the other was carried out in the absence of the DABCO pillar. Both reactions afforded crystals of different colours, i.e. violet plates for (I) and blue needles for (II), both of which were analysed by X‐ray crystallography. The 3,3′‐TPDC bridging ligands coordinate the Cu^II ions in asymmetric chelating modes in (I) and in monodenate binding modes in (II), forming one‐dimensional chains in each case. Both coordination polymers contain two coordinated dimethylamine ligands in mutually trans positions, and there is an additional aqua ligand in (II). The solvent water molecules are involved in hydrogen bonds between the one‐dimensional coordination polymer chains, forming a two‐dimensional network in (I) and a three‐dimensional network in (II).     

Copper‐Catalyzed Propargylic Substitution of Dichloro Substrates: Enantioselective Synthesis of Trisubstituted Allenes and Formation of Propargylic Quaternary Stereogenic Centers

An easy and versatile Cu‐catalyzed propargylic substitution process is presented. Using easily prepared prochiral dichloro substrates, readily available Grignard reagents together with catalytic amount of copper salt and chiral ligand, we accessed a range of synthetically interesting trisubstituted chloroallenes. Substrate scope and nucleophile scope are broad, providing generally high enantioselectivity for the desired 1,3‐substitution products. The enantioenriched chloroallenes could be further transformed into the corresponding trisubstituted allenes or terminal alkynes bearing all‐carbon quaternary stereogenic centers, through the copper‐catalyzed enantiospecific 1,1/1,3‐substitutions. The two successive copper‐catalyzed reactions could be eventually combined into a one‐pot procedure and different desired allenes or alkynes were obtained respectively with high enantiomeric excesses.     

Synthesis,Characterizations, Magnetism and Thermal Degradation of a 2‐Fold Interpenetrated 3D Cobalt‐Organic Framework

A new coordination polymer, [Co₂(L)₂(4,4′‐bipy)]_n·3nH₂O ( 1 ) based on 5‐(3‐methyl‐5‐phenyl‐4H‐1,2,4‐triazol‐4‐yl)isophthalic acid (H₂ L ) and 4,4′‐bipyridine (4,4′‐bipy) has been hydrothermally synthesized and characterized by single‐crystal X‐ray diffraction, XRPD, IR, and elemental analysis. Temperature‐dependent magnetic susceptibility and thermal degradation for 1 were also studied. The asymmetric unit of compound 1 consists of two crystallographically independent Co(II) ion, two L ^2? ligand, one 4,4′‐bipy ligand, and three lattice water molecules. The 2D triangle networks were linked by the bridging 4,4′‐bipy ligand to give rise to a 2‐fold interpenetrated 3D architecture. The simplest cyclic motif of the 2D networks is a triangle ring consisting of three Co(II) cations and three L ^2? ligands. So we can define Co(II) ions as 4‐connected nodes and the L ^2? ligands as 3‐connected nodes. Thus, the 3D structure can be described as a 2‐fold parallel interpenetrated ins InS 3,4‐conn topology.     

Preparation of Fluorescent Polystyrene via ATRP with Dimethylamino Chalcones as Initiator

4‐(3‐(4‐(Dimethylamino)phenyl)acryloyl)phenyl‐2‐bromo‐2‐methylpropanoate (APPBr) was used for the heterogeneous atom transfer radical polymerization (ATRP) of styrene (St) with copper(I) bromide/N,N,N′,N′′,N′′‐pentamethyldiethylenetriamine (PMDETA) catalytic system. The functional end group was characterized via UV‐Vis and ¹H NMR spectra. The polymerization showed a first‐order kinetic characteristic and each of the obtained polymers had well‐controlled molecular weight and relatively low polydispersity index (PDI). Furthermore, the obtained end‐functionalized polystyrene (PS) in solution showed strong green‐light emission which is further affected by mixing different metal cations. In particular, the fluorescent intensity of the polymer was decreased in the presence of Ag⁺, Cu²⁺ and Fe³⁺.     

Improving the Alkaline Stability of Imidazolium Cations by Substitution

Imidazolium cations are promising candidates for preparing anion‐exchange membranes because of their good alkaline stability. Substitution of imidazolium cations is an efficient way to improve their alkaline stability. By combining density functional theory calculations with experimental results, it is found that the LUMO energy correlates with the alkaline stability of imidazolium cations. The results indicate that alkyl groups are the most suitable substituents for the N3 position of imidazolium cations, and the LUMO energies of alkyl‐substituted imidazolium cations depend on the electron‐donating effect and the hyperconjugation effect. Comparing 1,2‐dimethylimidazolium cations (1,2‐DMIm⁺) and 1,3‐dimethylimidazolium cations (1,3‐DMIm⁺) with the same substituents reveals that the hyperconjugation effect is more significant in influencing the LUMO energy of 1,3‐DMIms. This investigation reveals that LUMO energy is a helpful aid in predicting the alkaline stability of imidazolium cations.     

A New Cyclic Peptide and a New Steroid from the Fungus Penicillium sp. GD6 Isolated from the Mangrove Bruguiera gymnorrhiza

A rare new cyclic tetrapeptide, 5,5′‐epoxy‐MKN‐349A ( 1 ), featured by a MKN‐349A ( 5 ) skeleton and containing an uncommon ether bridge between C(5) and C(5′), and a new steroid, named 11‐O‐acetyl‐NGA0187 ( 2 ), together with two known steroids, 3 and 4 , were isolated from an endophytic fungus Penicillium sp. GD6 associated with the Chinese mangrove Bruguiera gymnorrhiza. The structures of the new compounds were elucidated on the basis of extensive spectroscopic analyses and by comparison with the data of related compounds reported in literature. Neither of the compounds 3 and 4 , isolated in this study, showed obvious bioactivities in the antibacterial bioassay experiments.     

Determination of 12 potential nephrotoxicity biomarkers in rat serum and urine by liquid chromatography with mass spectrometry and its application to renal failure induced by Semen Strychni

In previous nephrotoxicity metabonomic studies, several potential biomarkers were found and evaluated. To investigate the relationship between the nephrotoxicity biomarkers and the therapeutic role of Radix Glycyrrhizae extract on Semen Strychni‐induced renal failure, 12 typical biomarkers are selected and a simple LC–MS method has been developed and validated. Citric acid, guanidinosuccinic acid, taurine, guanidinoacetic acid, uric acid, creatinine, hippuric acid, xanthurenic acid, kynurenic acid, 3‐indoxyl sulfate, indole‐3‐acetic acid, and phenaceturic acid were separated by a Phenomenex Luna C₁₈ column and a methanol/water (5 mM ammonium acetate) gradient program with a runtime of 20 min. The prepared calibration curves showed good linearity with regression coefficients all above 0.9913. The absolute recoveries of analytes from serum and urine were all more than 70.4%. With the developed method, analytes were successfully determined in serum and urine samples within 52 days. Results showed that guanidinosuccinic acid, guanidinoacetic acid, 3‐indoxyl sulfate, and indole‐3‐acetic acid (only in urine) were more sensitive than the conventional renal function markers in evaluating the therapeutic role of Radix Glycyrrhizae extract on Semen Strychni‐induced renal failure. The method could be further used in predicting and monitoring renal failure cause by other reasons in the following researches.     

Urinary metabolomic study of non‐small cell lung carcinoma based on ultra high performance liquid chromatography coupled with quadrupole time‐of‐flight mass spectrometry

Metabolic profiles from human urine reveal the significant difference of carnitine and acylcarnitines levels between non‐small cell lung carcinoma patients and healthy controls. Urine samples from cancer patients and healthy individuals were assayed in this metabolomic study using ultra high performance liquid chromatography coupled to quadrupole time‐of‐flight mass spectrometry. The data were normalized by the sum of all intensities and creatinine calibration, respectively, before orthogonal partial least squares discriminant analysis. Twenty differential metabolites were identified based on standard compounds or tandem mass spectrometry fragments. Among them, some medium‐/long‐chain acylcarnitines, for example, cis‐3,4‐methylene heptanoylcarnitine, were found to be downregulated while carnitine was upregulated in urine samples from the cancer group compared to the control group. Receiver operating characteristic analysis of the two groups showed that the area under curve for the combination of carnitine and 11 selected acylcarnitines was 0.958. This study suggests that the developed carnitine and acylcarnitines profiling method has the potential to be used for screening non‐small cell lung carcinoma.