Benign Approaches for the Microwave‐assisted Synthesis of Five‐membered 1,2‐N,N‐heterocycles

The development of new strategies for the synthesis of small‐sized heterocycles has remained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in the synthesis of two nitrogen atoms containing five‐membered heterocyclic compounds is presented, focusing on the developments in the last 5–10 years. This contribution covers the literature concerning the total synthesis of five‐membered 1,2‐N,N‐heterocycles.     

Phase stabilisation of blue-phase liquid crystals using a polymerisable chiral additive

We report a novel polymer stabilisation of blue phase by a chiral agent itself without additional reactive monomers. In this way, the structural difference in phase stabilisation gives rise to novel electro-optic properties such as the hysteresis-free with low-operating voltages. The number of constituents in polymer-stabilised blue-phase mixture is reduced and the polymer network more directly engages the structure of the blue phase, so that the hysteresis is free with less contamination for liquid crystals to be rearranged by electric fields. Also, relatively low operating voltage is achieved because the chiral pitch becomes longer owing to the chiral agent becoming polymerised. This result would open up an innovative way from a material perspective on stabilisation of blue-phase liquid crystals.     

Synthesis and optical behaviors of 6-seleno-deoxyguanosine

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Synthesis of Highly Stable,Water‐Dispersible Copper Nanoparticles as Catalysts for Nitrobenzene Reduction

We report an aqueous‐phase synthetic route to copper nanoparticles (CuNPs) using a copper–surfactant complex and tests of their catalytic efficiency for a simple nitrophenol reduction reaction under atmospheric conditions. Highly stable, water‐dispersed CuNPs were obtained with the aid of polyacrylic acid (PAA), but not with other dispersants like surfactants or polymethacrylic acid (PMAA). The diameter of the CuNPs could be controlled in the range of approximately 30–85 nm by modifying the ratio of the metal precursor to PAA. The catalytic reduction of p‐nitrophenol to p‐aminophenol takes place at the surface of CuNPs at room temperature and was accurately monitored by UV/Vis spectroscopy. The catalytic efficiency was found to be remarkably high for these PAA‐capped CuNPs, given the fact that at the same time PAA is efficiently preventing their oxidation as well. The activity was found to increase as the size of the CuNPs decreased. It can therefore be concluded that the synthesized CuNPs are catalytically highly efficient in spite of the presence of a protective PAA coating, which provides them with a long shelf life and thereby enhances the application potential of these CuNPs.     

Halogenated C,N‐diarylacetamides: molecular conformations and supramolecular assembly

The structures of four halogenated N,2‐diarylacetamides are reported and compared with a range of analogues. N‐(4‐Chloro‐3‐methylphenyl)‐2‐phenylacetamide, C₁₅H₁₄ClNO, (I), and N‐(4‐bromo‐3‐methylphenyl)‐2‐phenylacetamide, C₁₅H₁₄BrNO, (II), are isostructural in the space group P. The molecules of (I) and (II) are linked into chains of rings by a combination of N—H...O and C—H...π(arene) hydrogen bonds. The molecules of N‐(4‐chloro‐3‐methylphenyl)‐2‐(2,4‐dichlorophenyl)acetamide, C₁₅H₁₂Cl₃NO, (III), and N‐(4‐bromo‐3‐methylphenyl)‐2‐(2‐chlorophenyl)acetamide, C₁₅H₁₃BrClNO, (IV), are linked into simple C(4) chains by N—H...O hydrogen bonds, but significant C—H...π(arene) interactions are absent. The N‐aryl groups in compounds (III) and (IV) adopt a different orientation, by ca 180°, from that of the corresponding groups in compounds (I) and (II), but otherwise the conformations of (I)–(IV) are very similar. Comparisons are drawn between compounds (I) and (IV) and a range of analogues of the type R¹CH₂CONHR², where R² represents a halogenated aryl ring and R¹ represents either another halogenated aryl ring or a naphthalen‐1‐yl unit.     

Selective,Nanomolar Electrochemical Determination of Environmental Contaminants Dihydroxybenzene Isomers Found in Water Bodies Using Nanocrystalline Zeolite Modified Carbon Paste Electrodes

Nanocrystalline zeolites of different framework structures were prepared by the addition of suitable structure directing agents in the synthesis composition of conventional zeolites. Zeolite modified carbon paste electrodes were constructed for the simultaneous determination of dihydroxybenzene isomers. Nanocrystalline zeolite Beta modified carbon paste electrode exhibited the highest electrocatalytic activity. Under optimum conditions, wide linear range was obtained from 150 nM to 400 µM with lower detection limit of 100, 130, and 100 nM for hydroquinone, catechol, and resorcinol, respectively. The analytical performance of the proposed sensor was demonstrated in the simultaneous determination of dihydroxybenzene isomers in different environmental water samples.     

Pharmacophore and docking-based virtual screening approach for the design of new dual inhibitors of Janus kinase 1 and Janus kinase 2

Janus kinase 1 and 2, non-receptor protein tyrosine kinases, are implicated in various cancerous diseases. Involvement of these two enzymes in the pathways that stimulate cell proliferation in cancerous conditions makes them potential therapeutic targets for designing new dual-targeted agents for the treatment of cancer. In the present study, two separate pharmacophore models were developed and the best models for JAK1 (AAADH.25) and JAK2 (ADRR.92) were selected on the basis of their external predictive ability. Both models were subjected to a systematic virtual screening (VS) protocol using a PHASE database of 1.5 million molecules. The hits retrieved in VS were investigated for ADME properties to avoid selection of molecules with a poor pharmacokinetic profile. The molecules considered to be within the range of acceptable limits of ADME properties were further employed for docking simulations with JAK1 and JAK2 proteins to explore the final hits that possess structural features of both pharmacophore models as well as display essential interactions with both of them. Thus, the new molecules obtained in this way should show inhibitory activity against JAK1 and JAK2 and may serve as novel therapeutic agents for the treatment of cancerous disease conditions.     

Kinetics and TL glow curve study of europium-activated strontium aluminate

The present paper reports the thermoluminescence (TL) glow curve of Eu²⁺-activated SrAl₂O₄ phosphor with different UV exposure times. Evaluation of kinetic parameters was done by the peak shape method. The recorded glow curve shifts towards lower temperatures with respect to increasing UV exposure time. The peaks were found at 146.76, 141.34 and 140.37 °C, respectively, for 5, 10 and 15 min of UV exposure using the heating rate of 3°C s^?1. The glow peak shows the second-order kinetics. Different kinetic parameters, i.e. trap depth, order of kinetics, activation energy, and frequency factor are also calculated. The XRD pattern of the sample is compared with reported XRD using the software match.     

A Novel Synthetic Protocol for the Heteroannulation of Oxocarbazole and Oxoazacarbazole Derivatives through Corresponding Oxoketene Dithioacetals

An efficient novel strategy for the heteroannulation of 6,7‐dihydropyrazolo[3,4‐b]carbazol‐8(1H,5H,9H)‐one 4 and 5‐N‐benzyl‐6,7‐dihydropyrazolo[3,4‐b]carbazol‐8(1H,9H)‐one 5 has been developed to allow the incorporation of pyrazole, isoxazole, pyrimidine, benzodiazepine, and benzothiazepine rings through their corresponding oxoketene dithioacetal derivatives 6 and 7 , respectively.     

Synthesis and Antibacterial Activity of New 2,5‐Diaryl‐3‐styryl‐4H,2,3,3a,5,6,6a‐hexahydropyrrolo[3,4‐d]isoxazole‐4,6‐diones

The synthesis of some biologically interesting pyrrolo‐isoxazolidine derivatives has been accomplished by the 1,3‐dipolar cycloaddition reaction of substituted open chain conjugated azomethine N‐oxides 1 with substituted N‐aryl maleimides 2 leading to the formation of new stereoisomeric 2,5‐diaryl‐3‐styryl‐4H,2,3,3a,5,6,6a‐hexahydropyrrolo[3,4‐d]isoxazole‐4,6‐dione derivatives 3 in excellent yields. These stereoisomers have been characterized as cis‐ 3A and trans‐ 3B on the basis of their ¹H‐NMR spectral measurements. The synthesized compounds have been screened for their antibacterial activities and have been found to be active against the bacteria Escherichia coli and Pseudomonas aeruginosa up to a significant extent.