基于拓扑指数对含氧有机化合物闪点的定量构效关系研究

闪点是衡量化合物易燃程度的物理量,也是可燃性液体的一个重要安全性指标。本文对含氧有机化合物(包括醇、酚、醚、醛、酮、羧酸、酯等)的闪点与分子结构之间的关系进行分析,提取并计算了顶点度-距离指数(VDI)、奇偶指数(OEI)、边度-距离指数(EDI)、分子体积参数(MVI)和氢键指示变量(HB)等分子结构参数,并结合分子隐氢图顶点数(N)的2/3次方(N~(2/3)),对训练集中81个含氧有机化合物的闪点进行定量结构-性质相关分析。结果表明,由N~(2/3)、VDI、EDI、OEI、MVI和HB等6个参数对闪点建立的多元线性回归模型的相关系数(R)为0.9909,标准偏差(s)为6.39K,平均相对误差(ARD)为1.60%。用该模型对测试集中20个含氧有机化合物的闪点进行了预测,ARD为1.84%。     

3‐(Pyridin‐4‐yl)acetylacetone: CdII and HgII compete for nitrogen coordination

3‐(Pyridin‐4‐yl)acetylacetone (HacacPy) acts as a pyridine‐type ligand towards Cd^II and Hg^II halides. With CdBr₂, the one‐dimensional polymer [Cd(μ‐Br)₂(HacacPy)Cd(μ‐Br)₂(HacacPy)₂]_∞ is obtained in which five‐ and six‐coordinated Cd^II cations alternate in the chain direction. Reaction of HacacPy with HgBr₂ results in [Hg(μ‐Br)Br(HacacPy)]_∞, a polymer in which each Hg^II centre is tetracoordinated. In both compounds, each metal(II) cation is N‐coordinated by at least one HacacPy ligand. Equimolar reaction between these Cd^II and Hg^II derivatives, either conducted in ethanol as solvent or via grinding in the solid state, leads to ligand redistribution and the formation of the well‐ordered bimetallic polymer catena‐poly[[bromidomercury(II)]‐μ‐bromido‐[aquabis[4‐hydroxy‐3‐(pyridin‐4‐yl)pent‐3‐en‐2‐one]cadmium(II)]‐di‐μ‐bromido], [CdHgBr₄(C₁₀H₁₁NO₂)₂(H₂O)]_n or [{HgBr}(μ‐Br){(HacacPy)₂Cd(H₂O)}(μ‐Br)₂]_∞. Hg^II and Cd^II cations alternate in the [100] direction. The HacacPy ligands do not bind to the Hg^II cations, which are tetracoordinated by three bridging and one terminal bromide ligand. The Cd^II centres adopt an only slightly distorted octahedral coordination. Three bromide ligands link them in a (2 + 1) pattern to neighbouring Hg^II atoms; two HacacPy ligands in a cis configuration, acting as N‐atom donors, and a terminal aqua ligand complete the coordination sphere. Classical O—H…Br hydrogen bonds stabilize the polymeric chain. O—H…O hydrogen bonds between aqua H atoms and the uncoordinated carbonyl group of an HacacPy ligand in a neighbouring strand in the c direction link the chains into layers in the (010) plane.     

A three‐dimensional cadmium coordination polymer based on 1,4‐bis(1,2,4‐triazol‐1‐yl)but‐2‐ene and benzene‐1,3,5‐tricarboxylic acid

The Cd^II three‐dimensional coordination poly[[[μ₄‐1,4‐bis(1,2,4‐triazol‐1‐yl)but‐2‐ene]bis(μ₃‐5‐carboxybenzene‐1,3‐dicarboxylato)dicadmium(II)] dihydrate], {[Cd₂(C₉H₄O₆)₂(C₈H₁₀N₆)]·2H₂O}_n , (I), has been synthesized by the hydrothermal reaction of Cd(NO₃)₂·4H₂O, benzene‐1,3,5‐tricarboxylic acid (1,3,5‐H₃BTC) and 1,4‐bis(1,2,4‐triazol‐1‐yl)but‐2‐ene (1,4‐btbe). The IR spectrum suggests the presence of protonated carboxylic acid, deprotonated carboxylate and triazolyl groups. The purity of the bulk sample was confirmed by elemental analysis and X‐ray powder diffraction. Single‐crystal X‐ray diffraction analysis reveals that the Cd^II ions adopt a five‐coordinated distorted trigonal–bipyramidal geometry, coordinated by three O atoms from three different 1,3,5‐HBTC²⁻ ligands and two N atoms from two different 1,4‐btbe ligands; the latter are situated on centres of inversion. The Cd^II centres are bridged by 1,3,5‐HBTC²⁻ and 1,4‐btbe ligands into an overall three‐dimensional framework. When the Cd^II centres and the tetradentate 1,4‐btbe ligands are regarded as nodes, the three‐dimensional topology can be simplified as a binodal 4,6‐connected network. Thermogravimetric analysis confirms the presence of lattice water in (I). Photoluminescence studies imply that the emission of (I) may be ascribed to intraligand fluorescence.     

A new two‐dimensional polymeric cadmium(II) complex containing dicyanamide bridging ligands

As part of an exploration of new coordination polymers, a cadmium‐dicyanamide complex, namely poly[benzyltriethylammonium [tri‐μ‐dicyanamido‐κ⁶N ¹:N⁵‐cadmium(II)]], {(C₁₃H₂₂N)[Cd(C₂N₃)₃]}_n , has been synthesized by the reaction of benzyltriethylammonium bromide, cadmium nitrate tetrahydrate and sodium dicyanamide in aqueous solution, and characterized by single‐crystal X‐ray diffraction at room temperature. In the crystal structure, each Cd^II cation is coordinated by six nitrile N atoms from six anionic dicyanamide (dca) ligands to furnish a slightly distorted octahedral geometry. Neighbouring Cd^II cations are linked by dicyanamide bridges to construct a two‐dimensional anionic layer coordination polymer. One amide N atom in the bridging dca ligand is disordered over two sites. The cations lie between the anionic frameworks and there are no hydrogen‐bond interactions between the cations and anions. The organic cations are not involved in the formation of the supramolecular network.     

Structural rearrangement and stiffening of hydrophobically modified supramolecular hydrogels during thermal annealing

Dynamic crosslinks formed by thermoreversible associations provide an energy dissipation mechanism to toughen hydrogels. However, the details of the organization of these crosslinks impact the hydrogel properties through constraints on the network chain conformation. The physical crosslinks generated by hydrophobic association of the 2‐(N‐ethylperfluorooctane‐sulfonamido)ethyl methacrylate (FOSM) groups in a random copolymer of N,N‐dimethylacrylamide (DMA) and FOSM provide a simple system to investigate how the hydrogel structure (as determined from small angle neutron scattering impacts the mechanical properties of the hydrogel. The initial hydration of the copolymer at 25 °C leads to a kinetically trapped structure with large‐scale heterogeneities. Heating the hydrogel at 60 °C, which is above the glass transition temperature for the FOSM domains, allows the hydrogel structure to rearrange to reduce the density of network defects and the structural heterogeneities. That effectively increases the crosslink density of the network, which stiffens the hydrogel and decreases the swelling at equilibrium at 25 °C. The processing history determines how the hydrophobes aggregate to form the physically crosslinked network, whose structure defines the mechanical properties of these hydrogels. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1036–1044     

Three‐dimensional printed magnetophoretic system for the continuous flow separation of avian influenza H5N1 viruses

As a result of the low concentration of avian influenza viruses in samples for routine screening, the separation and concentration of these viruses are vital for their sensitive detection. We present a novel three‐dimensional printed magnetophoretic system for the continuous flow separation of the viruses using aptamer‐modified magnetic nanoparticles, a magnetophoretic chip, a magnetic field, and a fluidic controller. The magnetic field was designed based on finite element magnetic simulation and developed using neodymium magnets with a maximum intensity of 0.65 T and a gradient of 32 T/m for dragging the nanoparticle–virus complexes. The magnetophoretic chip was designed by SOLIDWORKS and fabricated by a three‐dimensional printer with a magnetophoretic channel for the continuous flow separation of the viruses using phosphate‐buffered saline as carrier flow. The fluidic controller was developed using a microcontroller and peristaltic pumps to inject the carrier flow and the viruses. The trajectory of the virus–nanoparticle complexes was simulated using COMSOL for optimization of the carrier flow and the magnetic field, respectively. The results showed that the H5N1 viruses could be captured, separated, and concentrated using the proposed magnetophoretic system with the separation efficiency up to 88% in a continuous flow separation time of 2 min for a sample volume of 200 μL.     

Identification and quantitative analysis of physalin D and its metabolites in rat urine and feces by liquid chromatography with triple quadrupole time‐of‐flight mass spectrometry

Physalin D is known to show extensive bioactivities. However, no excretion study has elucidated the excretion of physalin D and its metabolites. This study investigates the excretion of physalin D and its metabolites in rats. Metabolites in rat urine and feces were separated and identified by liquid chromatography with triple quadrupole time‐of‐flight mass spectrometry. Furthermore, a validated high‐performance liquid chromatography with tandem mass spectrometry method was developed to quantify physalin D, physalin D glucuronide, and physalin D sulfate in rat feces and urine after the intragastric administration of physalin D. The analyte showed good linearity over a wide concentration range (r  > 0.995), and the lower limit of quantification was 0.0532 μg/mL and 0.226 μg/g for urine and feces, respectively. Nine metabolites, including five phase I and four phase II metabolites, were identified and clarified after dosing in vivo. Only 4.0% of the gavaged dose, including physalin D and its phase II metabolites, was excreted in urine, whereas 10.8% was found in feces in the unchanged form. The results indicate that the extensive and rapid metabolism may be the main factors leading to the short half‐life of physalin D. These results can provide a basis for further studies on the structural modification and pharmacology of physalin D.     

Anti‐inflammatory bioactive equivalence of combinatorial components β‐carboline alkaloids identified in Arenaria kansuensis by two‐dimensional chromatography and solid‐phase extraction coupled with liquid–liquid extraction enrichment technology

Bioactive equivalent combinatorial components play a critical role in herbal medicines. However, how to discover and enrich them efficiently is a question for herbal pharmaceuticals researchers. In our work, a novel two‐dimensional reversed‐phase/hydrophilic interaction high‐performance liquid chromatography method was established to perform real‐time components trapping and combining for preparation and isolation of coeluting components. Arenaria kansuensis was taken as an example, and solid‐phase extraction coupled with liquid–liquid extraction as a simple and efficient method for enriching trace components, reversed phase column coupled with hydrophilic interaction liquid chromatography XAmide column as two‐dimensional chromatography technology for isolation and preparation of coeluting constituents, enzyme‐linked immune‐sorbent assay as bio‐guided assay, and anti‐inflammatory bioactivity evaluation for bioactive constituents. A combination of 12 β‐carboline alkaloids was identified as anti‐inflammatory bioactive equivalent combinatorial components from A. kansuensis , which accounts for 1.9% w/w of original A. kansuensis . This work answers the key question of which are real anti‐inflammatory components from A. kansuensis and provides a fast and efficient approach for discovering and enriching trace β‐carboline alkaloids from herbal medicines for the first time. More importantly, the discovery of bioactive equivalent combinatorial components could improve the quality control of herbal products and inspire a herbal medicine based on combinatorial therapeutics.     

Comprehensive two‐dimensional PC‐3 prostate cancer cell membrane chromatography for screening anti‐tumor components from Radix Sophorae flavescentis

Radix Sophorae flavescentis is generally used for the treatment of different stages of prostate cancer in China. It has ideal effects when combined with surgical treatment and chemotherapy. However, its active components are still ambiguous. We devised a comprehensive two‐dimensional PC‐3 prostate cancer cell membrane chromatography system for screening anti‐prostate cancer components in Radix Sophorae flavescentis . Gefitinib and dexamethasone were chosen as positive and negative drugs respectively for validation and optimization the selectivity and suitability of the comprehensive two‐dimensional chromatographic system. Five compounds, sophocarpine, matrine, oxymatrine, oxysophocarpine, and xanthohumol were found to have significant retention behaviors on the PC‐3 cell membrane chromatography and were unambiguously identified by time‐of‐flight mass spectrometry. Cell proliferation and apoptosis assays confirmed that all five compounds had anti‐prostate cancer effects. Matrine and xanthohumol had good inhibitory effects, with half maximal inhibitory concentration values of 0.893 and 0.137 mg/mL, respectively. Our comprehensive two‐dimensional PC‐3 prostate cancer cell membrane chromatographic system promotes the efficient recognition and rapid analysis of drug candidates, and it will be practical for the discovery of prostate cancer drugs from complex traditional Chinese medicines.     

Efficient separation of high‐purity compounds from Oxytropis falcata using two‐dimensional preparative chromatography

The separation of high‐purity compounds from traditional Tibetan medicines plays an important role in investigating their bioactivity. Nevertheless, it is often quite difficult to isolate compounds with high purity because of the complexity of traditional Tibetan medicines. In this work, an offline two‐dimensional reversed‐phase preparative method was successfully developed for the separation of high‐purity compounds from Oxytropis falcata . Based on the analysis results, an ODS C18 prep column was used for first‐dimensional preparation, and 14.8 g of the crude sample was separated into five fractions with a recovery of 74.6%. Then, an XAqua C18 prep column was used to isolate high‐purity compounds in the second‐dimensional preparation because its separation selectivity is different with the ODS C18 stationary phase. As a result, eight compounds in the crude sample were isolated in more than 98% purity. This is the first report of trans‐cinnamic acid ( 1 ) and trifolirhizin ( 2 ) from Oxytropis falcata . This method has the potential to be an efficient separation method of high‐purity compounds from Oxytropis falcata and it shows great promise for the separation of high‐purity compounds from complex samples.