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The residue of antibiotics in the soil is becoming more and more common, which may affect the normal growth of plants and organisms. The aim of this study was to investigate the residues of antibiotics in tea gardens' soil after a long-term application of manure. An ultra-high performance liquid chromatography-tandem mass spectrometry method was developed to simultaneously determine the residues of 32 antibiotics in the soil of tea gardens after fertilization. The samples were extracted with methanol-acetonitrile and purified with C18 at the same time. Then, mixed dispersive sorbents dispersed in a syringe were used for the second purification. The results showed that the antibiotics have a good linear relationship within the range. The recovery rate is 70.1-120.3%. The applicability of the method was demonstrated by analyzing 30 real samples (with a detection rate of 43.3%). The method is a simple and environmentally friendly method for the analysis of multiple antibiotics in soils, and it could provide a basis for the risk assessment of antibiotics in agricultural environments and the standard application of organic fertilizers in tea gardens.

This study established a detection method based on accelerated solvent extraction-liquid chromatography-mass spectrometry for determining residues of 3 chloramphenicols, 8 macrolides, 18 sulfonamides, 4 nitroimidazoles, 15 insecticides, and 22 fungicides in poultry feathers. The extraction solvent, methanol, was used for a static extraction time of 5 min, and repeated three times. Fifty milligrams of adsorbents C18/PSA (1 : 1, W/W) were added to the extraction cell to achieve simultaneous extraction and purification. The extraction efficiency of three solvents, methanol, acetonitrile and ethyl acetate, was investigated. An orthogonal experimental design was used to explore the optimal combination of extraction temperature, static extraction time, number of extraction cycles, and adsorbent ratio for accelerated solvent extraction. After the optimal ratio was determined, the dosage of adsorbents was optimized. The extracted sample solution was concentrated by blowing nitrogen, redissolved, passed through a 0.22 μm PTFE membrane filter, then injected for instrumental analysis. The validation results showed that the recovery of the proposed method was 60.4-107.6%, the limit of detection 0.2-3.0 μg kg

An efficient and convenient method was developed for the preparation of 3-sulfenylindoles via a cellulose-derived Fe3O4@Pd NPs catalyzed heterogeneously C–H sulfenylation of indoles. This approach provides an effective synthetic route to an important class of indoles derivatives and features high efficiency, easy operation, good practicality, and environmental friendliness. The recoverable catalyst was separated from the reaction mixture using an outside magnetic field and can be recycled five times without huge loss of catalytic performance. An efficient method was developed for the preparation of 3-sulfenylindoles via cellulose-derived Fe3O4@Pd NPs catalyzed heterogeneously C–H sulfenylation of indoles.

A novel magnetically recyclable nitrogen-doped Fe3O4@Pd NPs was prepared from the biomass-based materials which was employed as carbon and nitrogen source. The as-prepared catalysts were fully characterized by a variety of physicochemical techniques and were exploited for nitroaromatic hydrogenation with broad scope and excellent chemoselectivity using molecular hydrogen as a reductant. The heterogeneous catalysts can be recovered easily and reused for at least eight recycling reactions without obviously loss of catalytic properties. In addition, using this protocol, the key intermediate of marketed drug Osimertinib could be synthesized easily.

According to our search of the Cambridge Structural Database, a huge number of crystal structures involving intramolecular C S⋯O S(C) interactions were extracted. The largest proportion of these interactions in the crystals shows rather good linearity and short interatomic S⋯O distances. Then, intramolecular C S⋯O S(C) interactions in three representative organic molecules, i.e. sulfamethizole, thioindirubin, and thiazolo-pyridinium methide, were investigated using density functional theory calculations at the M06-2x level. The effects of different substituents and intermolecular hydrogen bonds on these interactions were also examined. The presence of both electron-withdrawing and electron-donating substituents into the donor moiety tends to strengthen intramolecular S⋯O bonds, while the formation of intermolecular hydrogen bonds has a complex influence. To gain a deeper understanding of the nature and strength of these interactions, the analyses of atom in molecules, noncovalent interaction index, and natural bond orbital were undertaken. Intramolecular chalogen bonds are weak electrostatic interactions and play a key role in controlling the crystal forms of relevant organic compounds, frequently supported by intermolecular hydrogen bonds.

In this report, novel glycosylpyridyl-triazole@nickel nanoparticles (GPT-Ni) were successfully prepared via click chemistry and were fully characterized by various spectroscopy measurements. The as-prepared catalysts could be used as a recyclable catalyst for the catalytic acylation of amines by employing N,N-dimethylacetamide (DMA), N,N-dimethylpropionamide (DMP), and N,N-dimethylformamide (DMF) as acylation reagents in water, providing the corresponding amides in good yields. The practicability of this methodology is highlighted by the good recyclability of the catalyst. A unique mechanism was proposed for the catalytic process.

Preparation of aluminosilicate ferrierite (FER) zeolite nanosheets with controllable thickness in the presence of a sole organic ammonium is attractive, but still challenging. In this report, with the employment of N,N-diethyl-cis-2,6-dimethylpiperidinium (DMP) as both a structure directing agent and crystal growth inhibitor, aluminosilicate FER zeolite nanosheets, with a variety of crystal thicknesses, ranging from 6 to 200 nm, are successfully synthesized under hydrothermal conditions. Very interestingly, the amount of DMP in the starting gel is the key factor for crystal thickness control of aluminosilicate FER zeolite nanosheets. The obtained FER products, with different thicknesses, are well characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), N2 sorption, thermogravimetric analysis (TG), inductively coupled plasma (ICP), and magic angle spinning nuclear magnetic resonance (MAS NMR) techniques. This simple strategy might provide a novel avenue for the synthesis of other zeolite nanosheets with controllable thickness.

A convenient and practical iodobenzene-catalyzed synthesis of trideuteroalkoxylated quinoxalinones has been developed under transition-metal-free conditions. The present transformation can be accomplished through C H/O H cross-dehydrogenative-coupling of quinoxalinones with deuterated alcohol. Various substrates are compatible, providing the corresponding products in moderate to good yields. A free radical pathway mechanism is advised for the transformation.

A syringe-dispersive solid-phase extraction method was developed for the determination of seven nitroimidazoles and nine steroids in manure-based fertilizers by ultra-high performance liquid chromatography with tandem mass spectrometry. Methanol and acetonitrile were used to extract the sample, and mixed dispersive sorbents dispersed in the syringe were used for purification. The extract was separated with an HSS-T3 column and detected in positive or negative multiple reaction monitoring mode. Under the optimal conditions, the recoveries of the 16 compounds ranged from 70.3 to 112.3% at the four spiked levels (3, 10, 20, and 50 μg/kg) and the relative standard deviations ranged from 1.0 to 12.4%. The limits of detection and quantification were 0.22-0.86 and 0.73-2.87 μg/kg, respectively. This method is simple, fast, and reliable, and can be used to simultaneously screen and determine nitroimidazoles and steroids in manure-based fertilizers.

Quasi-classical trajectory (QCT) calculations of H + HBr → H2+Br reaction have been performed on a recently proposed ab initio potential energy surface. The reaction probability and integral cross section are found to be in fairly good agreement with the available quantum mechanical (QM) results on this surface. The behavior of reactivity is well consistent with properties of exothermic reaction. Once the energy of vibrational excited HBr is larger than the barrier height, the integral cross sections for the reaction diverge at very low collision energies close to the threshold, similarly to capture reaction. In addition, differential cross sections show that scattering of the product H2 shift from backward to forward directions as the collision energy and vibrational quantum number increase. All the theoretical findings are reasonably explained by the properties of the surface, as well as reactive mechanisms.

Organic fluorines usually cannot act as halogen bond donors, as a result of the extreme electronegativity and least polarizability of the fluorine atom. However, when the electronegative ability of the substituents bound to the carbon atom is very strong, organic fluorines do show positive electrostatic potentials (ESPs) along the CF bond and thus can form halogen bonds with electron donors. In this work, the effects of six different substituents, i.e., NO2, CF3, CN, COOH, CHO, and CCH, on the ESPs of the F atom were studied using the M06-2x method. When two or three substituents with very strong electron-withdrawing ability, such as NO2 and CN, are linked to the C atom, positive ESPs take place on the outermost portion of the F atom. However, the ESPs remain negative along the CF bond with the introduction of relatively weak electron-withdrawing substituents, irrespective of the number of the subsituents. In addition, some complexes between fluorinated molecules with positive ESPs on the F atom and NH3 were calculated, to characterize the structural and energetic features of these specific halogen bonds. Finally, some crystal structures extracted from the Cambridge Structural Database were selected to provide experimental evidence of these interactions involving the CF bond. The results presented in this work are very important for the modern definition of halogen bonding as well as for the development of pharmaceuticals and a wide range of functional material. © 2015 Wiley Periodicals, Inc.

To elucidate the efficient removal and reliable storage of radioactive iodine for ionic liquids, halogen bonds in the complexes of I2 with a series of ion pairs were investigated at the M06-2x level of theory in this work. Albeit halogen bonds in these complexes are somewhat weaker than those in the systems of bare anions, these interactions still belong to strong halogen bonds and show some covalent character. The strength of these interactions deceases in the following order: [Cl]− ≈ [Br]− ≈ [I]− > [Ac]− ≈ [NO3]− > [BF4]−, consistent with the experimentally determined trend of the removal efficiency for corresponding ionic liquids. In addition, the electrostatic potential, atoms in molecules, and charge transfer analyses were also undertaken for the complexes under study, to gain a deeper understanding of the nature of these interactions.

Some lanthanide nitrate complexes with N-butylcaprolactam of general formula Ln( CH 2 (CH 2 ) 4 CON C4H9]3(NO3)3 have been prepared and characterized by means of elemental analysis and IR spectra. The crystal and molecular structures of Tm[ CH 2 (CH 2 ) 4 CON C4H9]3(NO3)3 and Nd[ CH 2 (CH 2 ) 4 CON C4H9]3(NO3)3 have been determined by single-crystal X-ray diffraction. The two complexes are isostructural and crystallize in the monoclinic system, space group P21/c. Thulium(III) [Nd(III) is coordinated thorugh three carbonyls of three organic ligands and the three nitrates are all bidentate ligands. So each Tm(III) [Nd(III)] is coordinated by nine oxygens, which form a distorted tricapped trigonal prism.