Synthesis,crystal structure and docking studies of tetracyclic 10‐iodo‐1,2‐dihydroisoquinolino[2,1‐b][1,2,4]benzothiadiazine 12,12‐dioxide and its precursors

The title compound, 10‐iodo‐1,2‐dihydroisoquinolino[2,1‐b][1,2,4]benzothiadiazine 12,12‐dioxide, C₁₅H₁₁IN₂O₂S ( 8 ), was synthesized via the metal‐free intramolecular N‐iodosuccinimide (NIS)‐mediated radical oxidative sp³‐C—H aminative cyclization of 2‐(2′‐aminobenzenesulfonyl)‐1,3,4‐trihydroisoquinoline, C₁₅H₁₆N₂O₂S ( 7 ). The amino adduct 7 was prepared via a two‐step reaction, starting from the condensation of 2‐nitrobenzenesulfonyl chloride ( 4 ) with 1,2,3,4‐tetrahydroisoquinoline ( 5 ), to afford 2‐(2′‐nitrobenzenesulfonyl)‐1,3,4‐trihydroisoquinoline, C₁₅H₁₄N₂O₄S ( 6 ), in 82% yield. The catalytic hydrogenation of 6 with hydrogen gas, in the presence of 10% palladium‐on‐charcoal catalyst, furnished 7 . Products 6 – 8 were characterized by their melting points, IR and NMR (¹H and ¹³C) spectroscopy, and single‐crystal X‐ray diffraction. The three compounds crystallized in the monoclinic space group, with 7 exhibiting classical intramolecular hydrogen bonds of 2.16 and 2.26 Å. All three crystal structures exhibit centrosymmetric pairs of intermolecular C—H…π(ring) and/or π–π stacking interactions. The docking studies of molecules 6 , 7 and 8 with deoxyribonucleic acid (PDB id: 1ZEW ) revealed minor‐groove binding behaviours without intercalation, with 7 presenting the most favourable global energy of the three molecules. Nonetheless, molecule 8 interacted strongly with the DNA macromolecule, with an attractive van der Waals energy of ?15.53 kcal mol^?1.     

Probabilistic representation and approximation for coupled systems of variational inequalities

Our study is dedicated to the probabilistic representation and numerical approximation of solutions of coupled systems of variational inequalities. We interpret the unique viscosity solution of a coupled system of variational inequalities as the solution of a one-dimensional constrained BSDE with jumps. This new representation allows for the introduction of a natural probabilistic numerical scheme for the resolution of these systems.     

Kinetics and mechanism of the reduction of diaquotetrakis (2,2′-bipyridine)-µ-oxodiruthenium(III) ion by hypophosphorous acid in acidic medium

The kinetics and mechanism of the reduction of diaquotetrakis(2,2′-bipyridine)-µ-oxodiruthenium(III), [(H₂O)₂(bipy)₄Ru₂O]⁴⁺, by H₃PO₂ has been studied in aqueous acid at ionic strength = 0.5 mol dm^?3 (NaClO₄), [H⁺] = 5.0 × 10^?2 mol dm^?3 and temperature = 31 ± 1 °C. Measurement of the stoichiometry showed that 1 mole of [(H₂O)₂(bipy)₄Ru₂O]⁴⁺ was reduced by 1 mole of H₃PO₂. The reaction was found to be first order with respect to both [(H₂O)₂(bipy)₄Ru₂O⁴⁺] and [H₃PO₂], hence second order overall. Variations in the ionic strength and dielectric constant of the reaction medium had no effect on the rate. Also, addition of various ions to the reaction medium did not significantly alter the rate. Free radicals were identified during the course of the reaction by a polymerisation test. Spectroscopic information and Michaelis–Menten plots suggested the absence of an intermediate complex prior to electron transfer. [(H₂O)₂(bipy)₂Ru]²⁺, the reduction product of [(H₂O)₂(bipy)₄Ru₂O]⁴⁺, plus H₃PO₃, the oxidation product of H₃PO₂, were identified in the product solutions. It is suggested that the reaction proceeds through the outer sphere pathway. A mechanism for the reaction is proposed.     

High-Performance Thin-Layer Chromatography Analysis of Saccharin in Foods and Beverages

JPC – Journal of Planar Chromatography – Modern TLC - A simple, accurate, and inexpensive high-performance thin-layer chromatography (HPTLC) method has been established for analysis of...     

On*-primes and*-valuations

We study the relation between^*-primes and^*-valuations to deduce a necessary and sufficient condition for extending^*-valuations.     

AnL 1 counting problem in ergodic theory

We give a negative solution to the following counting problem for measure preserving transformations. Forf∈L ₊ ¹ (μ), is it true that sup _n (N _n (f)(x)/n) <∞, μ a.e., where N _n (f)(x)=≠{k:f(T ^k x)/k >1/ n}? One of the consequences is the nonvalidity of J. Bourgain’s Return Time Theorem for pairs of (L ¹ ,L ¹ ) functions.     

Chemical constituents from the flowers of Satsuma mandarin and their free radical scavenging and α-glucosidase inhibitory activities

Flowers of Citrus plants are used as mild sedatives and for the treatment of insomnia in traditional medicines. In Japan, tea made from the flowers of Satsuma mandarin is consumed as healthy drink. Hesperidin (1), hesperetin (2), rutin (3), quercetin (4), nicotiflorin (5), eriocitrin (6), narirutin (7), phenylethyl glucoside (8) and unshuoside A (9) were isolated from the MeOH extract of fresh flowers. Structure elucidation of these compounds was performed on the basis of NMR spectroscopic data. Among them, rutin (3), quercetin (4) and eriocitrin (6) showed potent free radical scavenging activity, whereas hesperetin (2) and quercetin (4) showed potent α-glucosidase inhibitory activity.     

南极假丝酵母在纳米聚苯乙烯上的共价固载及其在微波辅助酯化反应中的应用（英文）

Nanopolystyrene was used as a solid support for the covalent immobilization of Candida antarctica lipase B(Cal B) using the photoreactive reagent 1‐fluoro‐2‐nitro‐4‐azido benzene(FNAB) as a cou‐pling reagent. The obtained derivative was then used as a biocatalyst in a microwave assisted ester‐ification experiment. Factors such as contact time, pH, and enzyme concentration were investigated during immobilization. The hydrolytic activity, thermal, and operational stability of immobi‐lized‐Cal B were determined. The maximum immobilized yield(218 μg/mg support) obtained at pH 6.8 exhibited optimum hydrolytic activity(4.42 × 103 mU p‐nitrophenol/min). The thermal stability of Cal B improved significantly when it was immobilized at pH 10, however, the immobilized yield was very low(93.6 μg/mg support). The immobilized‐Cal B prepared at pH 6.8 and pH 10 retained 50% of its initial activity after incubation periods of 14 and 16 h, respectively, at 60 °C. The opera‐tional stability was investigated for the microwave assisted esterification of oleic acid with metha‐nol. Immobilized‐Cal B retained 50% of its initial activity after 15 batch cycles in the micro‐wave‐assisted esterification. The esterification time was notably reduced under microwave irradia‐tion. The combined use of a biocatalyst and microwave heating is thus an alternative total green synthesis process.     

Dispersion of polymeric-coated–silica aerogel particles in unsaturated polyester composites: Effects on thermal-mechanical properties

The thermal-mechanical properties of unsaturated polyester (UP) composite were enhanced by the dispersion of silica aerogel (SA) with preserved pores. Low-cost SA was prepared from rice husk via the sol-gel process and ambient pressure drying. A new method was proposed to encapsulate the hydrophobic aerogel surface pores with hydrophilic polyvinyl alcohol (PVA) film using the fluidized-bed coating process. The dispersion of PVA-coated aerogel with preserved pores in the polyester matrix resulted in an increase of specific compressive strength (44.1?MPa?·?cm³?g^?1), thermal insulation (0.23?W?m^?1?K^?1), and thermal stability (T_onset?=?310°C), but decreased the glass transition temperature (T_g?=?260°C).