Single-atom ligand changes affect breathing in an extended metal-organic framework

2-Phenylpyridine-5,4'-dicarboxylic acid (1, dcppy), a derivative of 4,4'-biphenyldicarboxylic (2, bpdc) was used as the organic linking component for several metal-organic frameworks (MOFs). The pyridine component of 1 does not interfere with the solvothermal synthetic procedure, and hence both 1 and 2 form similar isoreticular MOFs. Zr(4+)-based UiO-67-dcppy, Al(3+)-based DUT-5-dcppy, Zn(2+)-based DMOF-1-dcppy, and interpenetrated Zn(2+)-based BMOF-1-dcppy were readily synthesized from 1. Similarly, isostructural frameworks from 2 were prepared (UiO-67, DUT-5, DMOF-1-bpdc, and interpenetrated BMOF-1-bpdc). The structures and physical properties of these frameworks were characterized by powder X-ray diffraction (PXRD), single X-ray diffraction (XRD), thermogravimetric analysis (TGA), and gas sorption analysis. Generally, frameworks prepared from 1 or 2 displayed similar properties; however, gas sorption data showed that BMOF-1-dcppy displayed a very large hysteresis with N(2) and CO(2) suggestive of possible framework flexibility. In contrast, the analogous framework prepared from 2 (BMOF-1-bpdc) showed low uptake of N(2) and CO(2). The substantial difference in the gas sorption behavior of these MOFs is attributed to the pyridine nature of 1 that results in weakened π-π interactions between the interpenetrated nets.     

Friedel–Crafts acylation using bismuth triflate in [BMI][PF6]

Bismuth trifluoromethanesulfonate was found to be a good catalyst for the Friedel–Crafts acylation. Bismuth triflate immobilized in an ionic liquid was the most efficient catalytic system. Bismuth triflate in [BMI][PF₆] catalyzes this reaction under microwave irradiation allowing the rapid synthesis of aryl ketones in excellent yields. The catalyst system was easily recovered and reused several times.     

NanoTiO2-聚苯胺复合膜电极电化学降解2,4,6-三硝基苯酚

利用溶胶-凝胶法和电化学聚合制得Ti/nanoTiO2-聚苯胺(PAn)复合膜电极,用X射线衍射仪、扫描电子显微镜及循环伏安法对电极的结构、表面形貌和电催化性能进行了表征。SEM测试表明,Ti/nanoTiO2-PAn电极上聚合的苯胺呈短纤维形貌,短纤维的直径较为均匀,为150 nm左右。以此电极进行电化学降解2,4,6-三硝基苯酚,在25℃,电解时间为180 min,电极间距离为2 cm,废水pH值在7～8之间,浓度为50 mg/L的2,4,6-三硝基苯酚模拟废水中COD,降解效率可达到41.2%。     

Thiol‐yne Click Adamantane Monolithic Stationary Phase for Capillary Electrochromatography

A porous crosslinked organic polymer based on N‐acryloxysuccinimide (NAS) and ethylene dimethacrylate (EDMA) was prepared inside 75 µm i.d. fused silica capillary as functionalizable monolithic stationary phase for electrochromatographic applications. Succinimide groups on the monolith surface provide reactive sites able to react readily through standard electrophile‐nucleophile chemistry. Propargylamine was used to prepare alkyne functionalized poly(NAS‐co‐EDMA). Onto this thiol‐reactive polymer surface was grafted adamantane units via a photochemically‐driven addition reaction. Chemical characterization was performed in situ after each synthetic step by means of Raman spectroscopy and grafting kinetics was investigated to ensure quantitative grafting of 1‐adamantanethiol. The as‐designed monolithic stationary phase exhibited typical reversed‐phase separation mechanism as evidenced by the linear increase of the logarithm of retention factor of neutral aromatic solutes with the increase of the aqueous buffer content in the mobile phase.     

Palladium-catalyzed Suzuki couplings using a novel diaminophosphine oxide as ligand

A novel diaminophosphine oxide was synthesized and applied as ligand in palladium-catalyzed Suzuki couplings reaction of aryl bromides and chlorides.The coupling reaction proceeded smoothly at mild conditions using 2 mol%Pd₂（dba）₃ in the presence of BuOK.     

Stationary Josephson current in junctions involving d-wave superconductors with charge density waves: the temperature dependence and deviations from the law of corresponding states

Stationary Josephson current I _c in symmetric and non-symmetric junctions involving d-wave superconductors with charge density waves (CDWs) was calculated. It was found that, if CDWs are weak or absent, there exists an approximate proportionality between I _c and the product of superconducting order parameters in the electrodes (the law of corresponding states) for several factors affecting those quantities, such as the temperature, T, or one of the parameters characterizing the combined CDW superconducting phase (the degree of the Fermi surface dielectric gapping and the ratio between the parent superconducting and CDW order parameters). Otherwise, the dependences I _c (T) were shown to deviate from those in the absence of CDWs, and the relevant corresponding-state dependences from linearity, the deviations being especially strong at certain rotation angles of crystalline electodes with respect to the junction plane. Hence, making use of specially designed experimental setups and analyzing the I _c (T) and corresponding-state dependences, the existence of CDWs in cuprates and other non-conventional superconductors can be detected.     

On qualitative properties of differential-algebraic equations

Linear systems of ordinary differential equations with identically degenerate coefficient matrix before the derivative of the unknown vector function are considered. The structure of general solutions and the notion of singular point of such systems are discussed. From the comparison of the properties of the “perturbed” and original problems, a sufficient criterion for the Lyapunov asymptotic stability of the zero solution is obtained.     

Optimizing a multi-stage production/inventory system by DC programming based approaches

This paper deals with optimizing the cost of set up, transportation and inventory of a multi-stage production system in presence of bottleneck. The considered optimization model is a mixed integer nonlinear program. We propose two methods based on DC (Difference of Convex) programming and DCA (DC Algorithm)—an innovative approach in nonconvex programming framework. The mixed integer nonlinear problem is first reformulated as a DC program and then DCA is developed to solve the resulting problem. In order to globally solve the problem, we combine DCA with a Branch and Bound algorithm (BB-DCA). A convex minorant of the objective function is introduced. DCA is used to compute upper bounds while lower bounds are calculated from a convex relaxation problem. The numerical results compared with those of COUENNE (http://www.coin-or.org/download/binary/Couenne/), a solver for mixed integer nonconvex programming, show the rapidity and the ?-globality of DCA in almost cases, as well as the efficiency of the combined DCA-Branch and Bound algorithm. We also propose a simple heuristic algorithm which is proved by experimental results to be better than an existing heuristic in the literature for this problem.