Computational insight into energetic cage derivatives based on hexahydro-1,3,5-trinitro-1,3,5-triazine

Four novel cage compounds were designed by introducing –N(NO₂)CH₂–, –N(NO₂)O–, –N(NO₂)N(NO₂)–, and –N=N– linkages into the RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) skeleton. Their molecular geometry, electronic structure, heat of formation, and detonation properties were systematically studied using density functional theory (DFT). In addition, the most stable dimers of the four compounds were constructed to further investigate their stability based on intermolecular interactions. It is found that the unconventional CH⋯O interactions would be the dominant driving force when the title compounds form crystals. Compared with the traditional explosives, the compounds with higher detonation properties and lower impact sensitivity will be considered as promising candidates for high energy density compounds. Our results indicate that our innovative design strategy is extremely useful for developing novel energetic compounds.     

结晶聚合物的辐射效应——多官能团单体对LDPE的结晶成核作用

根据x射线、电镜、DSC和凝胶分数的测试结果,讨论了多官能团单体结构对低密度聚乙烯聚集态结构的影响以及结晶度与辐射交联(或剂量)的关系。发现由于单体的存在导致低密度聚乙烯结晶度增加而结晶尺寸变小(即结晶成核效应);成核效应越大,增强辐射交联的效果也越大。添加具有高结晶成核作用的单体有利于低密度聚乙烯的辐射交联,同时也加速其结晶结构的破坏。     

Multifolded torus chaotic attractors: design and implementation

This paper proposes a systematic methodology for creating multifolded torus chaotic attractors from a simple three-dimensional piecewise-linear system. Theoretical analysis shows that the multifolded torus chaotic attractors can be generated via alternative switchings between two basic linear systems. The theoretical design principle and the underlying dynamic mechanism are then further investigated by analyzing the emerging bifurcation and the stable and unstable subspaces of the two basic linear systems. A novel block circuit diagram is also designed for hardware implementation of 3-, 5-, 7-, 9-folded torus chaotic attractors via switching the corresponding switches. This is the first time a 9-folded torus chaotic attractor generated by an analog circuit has been verified experimentally. Furthermore, some recursive formulas of system parameters are rigorously derived, which is useful for improving hardware implementation.     

具有超高阳离子染料去除能力的磺酸功能化球形共价有机框架

通过三醛基间苯三酚(TFP)与2,2′-联苯胺二磺酸(BDSA)的席夫碱反应, 合成了β-酮烯胺连接的磺酸功能化球形共价有机框架(TFP-BDSA COF). 所得阴离子型TFP-BDSA可迅速吸附如亚甲基蓝(MLB)、 结晶紫(CV)和罗丹明B(RhB)等阳离子染料, 而对如甲基橙(MO)和荧光素钠(FS)等阴离子染料则难以吸附, 该COF可实现基于电荷模式的阴离子、 阳离子染料的分离. TFP-BDSA对阳离子染料的吸附动力学均遵循拟二级吸附动力学模型, 吸附过程符合Langmuir吸附模型, 其对MLB, CV和RhB的最大吸附容量分别高达1116, 1429和1638 mg/g. 与其它COFs材料相比, TFP-BDSA对CV和RhB的吸附容量最高. 该工作可为开发功能COFs材料实现对废水中有机污染物的快速吸附和有效去除提供参考.     

Mechanism of the conversion of inverted CB[6] to CB[6

Inverted cucurbit[n]urils (iCB[n]) form as intermediates during the synthesis of cucurbit[n]urils from glycoluril and formaldehyde in HCl (85 degrees C). Product resubmission experiments establish that the diastereomeric iCB[6] and iCB[7] are kinetic products that are less stable thermodynamically than CB[6] or CB[7] (>2.8 kcal mol(-1)). When iCB[6] or iCB[7] is heated under aqueous acidic conditions, a preference for ring contraction is noted in the formation of CB[5] and CB[6], respectively. Interestingly, under anhydrous acidic conditions ring size is preserved with iCB[6] delivering CB[6] cleanly. To establish the intramolecular nature of the iCB[6] to CB[6] conversion under anhydrous, but not aqueous, acidic conditions we performed crossover experiments involving mixtures of iCB[6] and its (13)C=O labeled isotopomer (13)C(12)-iCB[6]. An unusual diastereomeric CB[6] with a M?bius geometry (13) is proposed as a mechanistic intermediate in the conversion of iCB[6] to CB[6] under anhydrous acidic conditions. The improved mechanistic understanding provided by this study suggests improved routes to CB[n]-type compounds.     

Synthesis, carbohydrate- and DNA-binding studies of cationic 2,2':6',2'-terpyridineplatinum(II) complexes containing N- and S-donor boronic acid ligands

A series of platinum(II) complexes of the type [Pt(trpy)L](NO(3))(n) (L = 3- or 4-pyridineboronic acid (3- or 4-pyB, respectively), n = 2; HL = 4-mercaptophenylboronic acid (HmpB), n = 1; trpy = 2,2':6',2'-terpyridine) and [{Pt(trpy)}(2)(μ-pzB)](NO(3))(3) (HpzB = 4-pyrazoleboronic acid) were synthesized and fully characterized by means of multinuclear ((1)H, (13)C, (11)B, and (195)Pt) 1D- and 2D-NMR spectroscopy and elemental analysis. The triflate derivatives [Pt(trpy)(4-pyB)](OTf)(2) and [{Pt(trpy)}(2)(μ-pzB)](OTf)(3) were also prepared, and their molecular structures were confirmed by X-ray crystallography. Variable pH (1)H NMR spectroscopy showed that hydroxylation of the boronic acid group occurs in aqueous solution at pH > 5 and the pK(a) values for the complexes were determined. In buffered aqueous solution (pH 7.4), the complexes bind strongly to simple diols such as catechol and monosaccharides including D-fructose, D-ribose, D-sorbitol and D-mannitol, as determined by isothermal titration calorimetry (ITC). The equilibrium binding constants for these reactions were determined and were found to exceed those of organic boronic acids such as phenylboronic acid by an order of magnitude or greater, an effect that can be directly attributed to the cationic charge of the complexes. 2D-NMR methods (HSQC and HMBC) were used to elucidate the structures of the carbohydrate adducts [Pt(trpy)(3-pyB)]·D-fructose·NO(3) and [Pt(trpy)(4-pyB)]·D-fructose·NO(3) in aqueous solution. DNA-binding experiments with calf-thymus DNA (CT-DNA) indicate an avid DNA-binding interaction by the mononuclear complexes, as determined using thermal melting methods and ITC, but the behaviour of the dinuclear species [{Pt(trpy)}(2)(μ-pzB)](NO(3))(3) is complicated and could not be modeled adequately; higher ionic strength solutions and lower temperatures resulted in a similar DNA binding interaction to the mononuclear complexes. The presence of excess d-fructose did not significantly affect the binding of the platinum(II)-trpy complexes to CT-DNA.     

Chromatographic behavior of IgM:DNA complexes

This study documents the presence of stable complexes between monoclonal IgM and genomic DNA in freshly harvested mammalian cell culture supernatants. 75% of the complex population elutes from size exclusion chromatography with the same retention volume as IgM. DNA comprises 24% of the complex mass, corresponding to an average of 347 base pairs per IgM molecule, distributed among fragments smaller than about 115 base pairs. Electrostatic interactions appear to provide most of the binding energy, with secondary stabilization by hydrogen bonding and metal affinity. DNA-dominant complexes are unretained by bioaffinity chromatography, while IgM-dominant complexes are retained and coelute with IgM. DNA-dominant complexes are repelled from cation exchangers, while IgM-dominant complexes are retained and partially dissociated. Partially dissociated forms elute in order of decreasing DNA content. The same pattern is observed with hydrophobic interaction chromatography. All complex compositions bind to anion exchangers and elute in order of increasing DNA content. A porous particle anion exchanger was unable to dissociate DNA from IgM. Monolithic anion exchangers, offering up to 15-fold higher charge density, achieved nearly complete complex dissociation. The charge-dense monolith surface appears to outcompete IgM for the DNA. Monoliths also exhibit more than double the IgM dynamic binding capacity of the porous particle anion exchanger, apparently due to better surface accessibility and more efficient mass transfer.     

Generation of multi-wing chaotic attractor in fractional order system

In this paper, a novel approach is proposed for generating multi-wing chaotic attractors from the fractional linear differential system via nonlinear state feedback controller equipped with a duality-symmetric multi-segment quadratic function. The main idea is to design a proper nonlinear state feedback controller by using four construction criterions from a fundamental fractional differential nominal linear system, so that the controlled fractional differential system can generate multi-wing chaotic attractors. It is the first time in the literature to report the multi-wing chaotic attractors from an uncoupled fractional differential system. Furthermore, some basic dynamical analysis and numerical simulations are also given, confirming the effectiveness of the proposed method.     

An improved synthesis of ‘octa-acid’ deep-cavity cavitand

An improved synthesis of a water-soluble deep-cavity cavitand (octa-acid, 1) is presented. Previously (Gibb, C.L.D.; Gibb, B.C. J. Am. Chem. Soc. 2004, 126, 11408–11409), we documented access to host 1 in eight (non-linear) steps starting from resorcinol; a synthesis that required four steps involving chromatographic purification. Here, we reveal a modified synthesis of host 1. Consisting of seven (non-linear) steps, this new synthesis involves only one chromatographic step, and avoids a minor impurity observed in the original approach. This improved synthesis is therefore useful for the laboratories that are investigating the properties of these types of host.     

Automatic on‐line solid‐phase extraction with ultra‐high performance liquid chromatography and tandem mass spectrometry for the determination of ten antipsychotics in human plasma

An automatic on‐line solid‐phase extraction with ultra‐high performance liquid chromatography and tandem mass spectrometry method was developed for the simultaneous determination of ten antipsychotics in human plasma. The plasma sample after filtration was injected directly into the system without any pretreatment. A Shim‐pack MAYI‐C₈ (G) column was used as a solid‐phase extraction column, and all the analytes were separated on a Shim‐pack XR‐ODS III column with a mobile phase consisting of 0.1% v/v formic acid in water with 5 mM ammonium acetate and acetonitrile. The method features were systematically investigated, including extraction conditions, desorption conditions, the equilibration solution, the valve switching time, and the dilution for column‐head stacking. Under the optimized conditions, the whole analysis procedure took only 10 min. The limits of quantitation were in the range of 0.00321–2.75 μg/L and the recoveries ranged from 75.9 to 122%. Compared with the off‐line ultra‐high performance liquid chromatography and the reported methods, this validated on‐line method showed significant advantages such as minimal pretreatment, shortest analysis time, and highest sensitivity. The results indicated that this automatic on‐line method was rapid, sensitive, and reliable for the determination of antipsychotics in plasma and could be extended to other target analytes in biological samples.