Experimental Investigation of Mechanical Properties of Golden Cane Fiber–Reinforced Polyester Composites

The main objective of this article is to introduce a new natural fiber as a reinforcement in polymers for making composites for lightweight applications. The extraction of golden cane (Chrysalidocarpus lutescens) fiber and the mechanical properties of the fiber-reinforced polyester composites are described. The composites were formulated up to a maximum volume fraction of 0.43, resulting in a mean tensile strength and modulus of 2.13 and 2.26 times and mean flexural strength and modulus of 1.94 and 2.89 times greater than those of plain polyester, respectively, at a higher volume fraction of 0.43. The work of fracture in impact is measured to be 358 J/m. The results of this study indicate that golden cane fibers have potential as reinforcing fillers in plastics in order to produce inexpensive materials with high toughness.     

Self‐Assembled Helical Arrays for the Stabilization of the Triplet State

Room‐temperature phosphorescence of metal and heavy atom‐free organic molecules has emerged as an area of great potential in recent years. A rational design played a critical role in controlling the molecular ordering to impart efficient intersystem crossing and stabilize the triplet state to achieve room‐temperature ultralong phosphorescence. However, in most cases, the strategies to strengthen phosphorescence efficiency have resulted in a reduced lifetime, and the available nearly degenerate singlet‐triplet energy levels impart a natural competition between delayed fluorescence and phosphorescence, with the former one having the advantage. Herein, an organic helical assembly supports the exhibition of an ultralong phosphorescence lifetime. In contrary to other molecules, 3,6‐phenylmethanone functionalized 9‐hexylcarbazole exhibits a remarkable improvement in phosphorescence lifetime (>4.1 s) and quantum yield (11 %) owing to an efficient molecular packing in the crystal state. A right‐handed helical molecular array act as a trap and exhibits triplet exciton migration to support the exceptionally longer phosphorescence lifetime.     

DMSO–POCl3: a reagent for methylthiolation of imidazo[1,2-a]pyridines and other imidazo-fused heterocycles

A practical and metal free method for methylthiolation of imidazo[1,2-a]pyridines and other imidazo-fused heterocycles using DMSO–POCl₃ complex is reported. The reactions are carried out at room temperature that give the corresponding methylthiolated products in good to excellent yield. Further, its application to indole has been demonstrated.     

Mechanistic investigation of oxidation of metronidazole and tinidazole with N-bromosuccinimide in acid medium: A kinetic approach

Metronidazole (MTZ) and tinidazole (TNZ) belong to nitroimidazole group of drugs used to treat infections such as ameobiasis, giardiasis and trichomoniasis. The kinetics of oxidation of MTZ and TNZ with _N-bromosuccinimide (NBS) in perchloric acid medium has been investigated at 308 K. A 1:1 stoichiometry has been observed in both MTZ and TNZ cases. The oxidation reactions of both MTZ and TNZ follow the same rate law, -d[NBS]/dt = [NBS][Sub][H⁺]. However, in case of MTZ, at higher concentrations of H⁺ (0.006–0.01 mol dm^?3), the rate law obtained is -d[NBS]/dt = [NBS][MTZ][H⁺]^?1. Accelerating effect of [Cl^-] and retardation of the added succinimide on the reaction rate have been observed in the case of MTZ. The reactions were examined with reference to changes in concentration of added neutral salt, ionic strength and dielectric permittivity of the medium. The overall activation parameters have been evaluated from the Arrhenius plot. The reactive oxidizing species of NBS have been determined. The main oxidation products were identified by IR and ¹H NMR spectral analyses. The observed results have been explained by plausible mechanisms and the relative rate laws have been deduced.     

Crystal Structure of 3-Oxo-4-Aza-5-Alpha-Androstone-17 β-<Emphasis Type="Italic">Tert</Emphasis>-Butyl Carboxamide with an O···H–(C,N) Acceptor Four-Center Hydrogen Bond

Abstract  The title compound, C₂₃H₃₈N₂O₂, is the saturated form of a modified steroid derivative Finasteride, containing a δ-lactamide ring, fused to successive cyclohexane and cyclopentane rings which contain a tert-butylamide residue. It crystallizes in the monoclinic space group C2 with unit cell parameters a = 9.99450(10), b = 7.67870(10), c = 28.4954(3), ?, β = 93.8706(10)°, Z = 4. Crystal packing effects are influenced by intermolecular hydrogen bond interactions dominated by an acceptor O···H–(C, N) four-center hydrogen bond interaction around the keto oxygen atom from the δ-lactamide ring in the asymmetric unit. Intramolecular three-center C–H···O hydrogen bonds around the tert-butylamide oxygen atom appear to have little effect on crystal packing. A comparison of the geometric parameters of the asymmetric unit (a 5α isomer) is made and with a solvated analog compound (a 5β isomer) and some solvated Finasteride compounds which differ only in the unsaturation of the C1=C2 bond in the δ-lactamide ring. The dihedral angle between the mean planes of the fused δ-lactamide and cyclohexane rings is 2.5(8)° which differs significantly from the 74.8(8) and 76.1(9)° values observed in the solvated analog compound and with its geometry optimized (MOPAC) computed structure, respectively. Index Abstract  Crystal structure of 3-oxo-4-aza-5-alpha-androstone-17 β-tert-butyl carboxamide with an O···H–(C, N) acceptor four-center hydrogen bond around the keto oxygen atom from the δ-lactamide ring in the asymmetric unit is reported and its geometric and packing parameters described and compared to related solvent and analog compounds and to a MOPAC computational calculation of the geometry optimized molecule. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Synthesis of pyrroles from alkyl trans-2-methyoxycyclopropyl ketones

2-Alkylpyrroles were obtained by the reaction of alkyl trans-2-methoxycyclopropyl ketones with ammonium hydroxide. N-Substituted 2-alkylpyrroles were synthesized by the reaction of the indicated ketones with methylamine or aniline in acetic acid or methanol-acetic acid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1335–1336, October, 1990.     

Microwave assisted synthesis of ring junction heterocyclic antioxidants

A series of 6,7-dihydro-[1,2,4]triazolo[5,1-b]quinazolin-8(5H)-ones, 4a–o were synthesized via a one-pot, multicomponent reaction in the presence of water as a solvent under microwave irradiation using ceric ammonium nitrate as an oxidizing agent. This techno-chemical method provides a rapid construction of higher molecules in short duration with high yield. The adopted method was carried out in the presence of water without catalyst and yielded the compounds without any side products, and thus further purification of compounds by column chromatography was not required. All the synthesized compounds, 4a–o were screened for their 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity. All the compounds, 4a–o possessed moderate antioxidant activity when compared to their standard antioxidant (ascorbic acid).     

Naringenin and quercetin – potential anti-HCV agents for NS2 protease targets

Nonstructural proteins of hepatitis C virus had drawn much attention for the scientific fraternity in drug discovery due to its important role in the disease. 3D structure of the protein was predicted using molecular modelling protocol. Docking studies of 10 medicinal plant compounds and three drugs available in the market (control) with NS2 protease were employed by using rigid docking approach of AutoDock 4.2. Among the molecules tested for docking study, naringenin and quercetin revealed minimum binding energy of ? 7.97 and ? 7.95 kcal/mol with NS2 protease. All the ligands were docked deeply within the binding pocket region of the protein. The docking study results showed that these compounds are potential inhibitors of the target; and also all these docked compounds have good inhibition constant, vdW+Hbond+desolv energy with best RMSD value.