Iron(II), cobalt(III), nickel(II) and copper(II) chelates of furan and thiophene azo-oximes

Summary Complexes of furan and thiophene azo-oximes with iron(II), cobalt(III), nickel(II) and copper(II) have been prepared and characterised. Iron(II), cobalt(III) and copper(II) complexes are diamagnetic in the solid state. The diamagnetism of the copper(II) chelates is suggestive of antiferromagnetic interaction between two copper centres.¹H n.m.r. spectral data suggest atrans-octahedral geometry for the tris-chelates of cobalt(III). Nickel(II) complexes are paramagnetic, in contrast to the diamagnetism of the analogous complexes of arylazooximes. The electronic spectra are suggestive of octahedral geometry for the iron(II), cobalt(III) and nickel(II) complexes, andD _4h -symmetry for copper(II). Infrared data indicate N-bonding of the oximino-group to the metal ions.     

Synthesis and spectral studies of cobalt(II), nickel(II) and copper(II) complexes of 1-(2-hydroxy-1-naphthyl)-3-(4-X-phenyl)-2-propen-1-ones and their pyridine adducts

Transition Metal Chemistry - Metal(II) chelates of the type ML2nB [M = CoII, NiII and CuII; L = 1-(2-hydroxy-1-naphthyl)-3-(4-X-phenyl)-2-pro-pen-1-one, (X = H, Cl or Me); B = H2O or Py; n = 0, 2]...     

Pressure induced amorphization of AlPO4

AlPO₄ has been compressed to pressures of 16 GPa in a diamond anvil cell and its X-ray diffraction pattern studied by the energy-dispersive technique. The compound is observed to become amorphous at ∼ 12 GPa. This explains the loss of Raman spectrum of AlPO₄ reported by Jayaraman and coworkers (1987).     

Rh2(OAc)4-catalyzed reactions of alpha-diazoimides: a simple and novel synthesis of mono- and bis(2,3-fused perhydrooxazol-4-one) systems

Simply, trapping the intermediate isomünchnone 1,3-dipoles by the external oxygen nucleophiles resulted in new heterocyclic systems and the use of diols led to the formation of four carbon-oxygen bonds in a single operation which eventually delivered bis(2,3-fused perhydrooxazol-4-one) systems.     

Potential functions for hydrogen bond interactions

A careful comparison of the distribution in the (R, θ)-plane of all NH … O hydrogen bonds with that for bonds between neutral NH and neutral C=O groups indicated that the latter has a larger mean R and a wider range of θ and that the distribution was also broader than for the average case. Therefore, the potential function developed earlier for an average NH … O hydrogen bond was modified to suit the peptide case. A three-parameter expression of the form \(V_{hb} = V_{min} + p_1 \Delta ^2 + q_1 e^{p_3 \Delta } \theta ^2 \) , with △ = R - R_min, was found to be satisfactory. By comparing the theoretically expected distribution in R and θ with observed data (although limited), the best values were found to bep ₁ = 25,p ₃ = ? 2 andq ₁ = 1 × 10^?3, with R_min = 2·95 Å and V_min = ? 4·5 kcal/mole. The procedure for obtaining a smooth transition from V_hb to the non-bonded potential V_nb for large R and θ is described, along with a flow chart useful for programming the formulae. Calculated values of ΔH, the enthalpy of formation of the hydrogen bond, using this function are in reasonable agreement with observation. When the atoms involved in the hydrogen bond occur in a five-membered ring as in the sequence a different formula for the potential function is needed, which is of the form V_hb = V_min +p ₁△² +q ₁ x ² wherex = θ ? 50° for θ ≥ 50°, withp ₁ = 15,q ₁ = 0·002, R_min = 2· Å and V_min = ? 2·5 kcal/mole.     

Structural models of quasicrystals: Significance of positron annihilation studies

We discuss implications of our results of positron annihilation studies of various icosahedral quasicrystalline alloys on the structural models of this new phase. We have studied Al-Mn, Al-Mn-Si, Al-Cu-Li and Al-Cu-Fe and a two component positron annihilation lifetime spectrum seems characteristics of all these icosahedral quasicrystalline alloy phases. Analysis of the lifetime spectra yields vacancy sizes varying from monovacancies to hexavacancies with concentration of 1 to 8 ppm in various quasicrystalline alloys. These vacancy concentrations are about three orders of magnitude less than that observed in metallic glasses. We also notice that in the case of metastable quasicrystalline alloys such as Al-Mn and Al-Mn-Si, these vacancy clusters disappear during the crystallization process resulting in single lifetime spectra. On the other hand, for stable quasicrystalline alloys, two component life time spectra, which indicate the presence of vacancy clusters, continue to exist even after prolonged heat treatment. Our results seem incompatible with the space filling Penrose tiling or random tiling models and favour cluster-based models.     

A novel mixed valence iodide bridged Te(II)-Te(IV) complex featuring diisopropyldithiocarbamate(L) and iodide: ILTeII(I)TeIVL2I

The title compound is a novel mixed ligand and mixed valence complex of tellurium, the crystal structure of which is reported here. The compound crystallizes in the orthorhombic space group, Pca2₁ with four molecules per unit cell, the dimensions of which area=15.209(1),b=20.159(2),c=12.453(1) Å. The structure was solved by the heavy-atom method and refined by fullmatrix least-squares method to a finalR=0.046 andR _w=0.046 for 3011 unique reflections. The structure could be considered as 11 adduct of Te^IVL₂I₂ and Te^IILI (L=diisopropyldithiocarbamate). The two tellurium atoms, Te^II[Te(1)] and Te^IV[Te(2)] display entirely different coordinations and are bridged through iodine I(1) in a symmetrical manner. There is a short Te(1)Te(2) contact distance of 3.542(1) Å.     

A Facile Reductive Cleavage of Allylic and Benzylic Esters with Low Valent Titanium Reagents

The reductive cleavage of allylic and benaylic esters 1a-g with titanium(II) reagent derived from Mg/Hg-TiCl yielded the corresponding acids 3a-g and dimeric hydro 4 carbons 2a-g under mild reaction conditions.     

The first total synthesis of cytopiloyne, an anti-diabetic, polyacetylenic glucoside

The first total synthesis of cytopiloyne 1, a novel bioactive polyacetylenic glucoside isolated from the extract of Bidens pilosa, is described. The structure of cytopiloyne was determined to be 2-β-D-glucopyranosyloxy-1-hydroxytrideca-5,7,9,11-tetrayne by using various spectroscopic methods, but the chirality of the polyyne moiety was unknown. Herein, the convergent synthesis of two diastereomers of cytopiloyne by starting from commercially available 4-(2-hydroxyethyl)-2,2-dimethyl-1,3-diozolane is described. The synthetic sequence involved two key steps: stereoselective glycosylation of the glucosyl trichloroacetimidate with 1-[(4-methoxybenzyl)oxy]hex-5-yn-2-ol to give the desired β-glycoside and the construction of the glucosyl tetrayne skeleton by using a palladium/silver-catalyzed cross-coupling reaction to form the alkyne-alkyne bond, the first such use of this reaction. Comparison between the observed and published characterization data showed the 2R isomer to be the natural product cytopiloyne.     

In Silico Molecular Docking Analysis of Karanjin against Alzheimer’s and Parkinson’s Diseases as a Potential Natural Lead Molecule for New Drug Design,Development and Therapy

Parkinson’s disease (PD) and Alzheimer’s disease (AD) are neurodegenerative disorders that have emerged as among the serious health problems of the 21st century. The medications currently available to treat AD and PD have limited efficacy and are associated with side effects. Natural products are one of the most vital and conservative sources of medicines for treating neurological problems. Karanjin is a furanoflavonoid, isolated mainly from Pongamia pinnata with several medicinal plants, and has been reported for numerous health benefits. However, the effect of karanjin on AD and PD has not yet been systematically investigated. To evaluate the neuroprotective effect of karanjin, extensive in silico studies starting with molecular docking against five putative targets for AD and four targets for PD were conducted. The findings were compared with three standard drugs using Auto Dock 4.1 and Molegro Virtual Docker software. Additionally, the physiochemical properties (Lipinski rule of five), drug-likeness and parameters including absorption, distribution, metabolism, elimination and toxicity (ADMET) profiles of karanjin were also studied. The molecular dynamics (MD) simulations were performed with two selective karanjin docking complexes to analyze the dynamic behaviors and binding free energy at 100 ns time scale. In addition, frontier molecular orbitals (FMOs) and density-functional theory (DFT) were also investigated from computational quantum mechanism perspectives using the Avogadro-ORCA 1.2.0 platform. Karanjin complies with all five of Lipinski’s drug-likeness rules with suitable ADMET profiles for therapeutic use. The docking scores (kcal/mol) showed comparatively higher potency against AD and PD associated targets than currently used standard drugs. Overall, the potential binding affinity from molecular docking, static thermodynamics feature from MD-simulation and other multiparametric drug-ability profiles suggest that karanjin could be considered as a suitable therapeutic lead for AD and PD treatment. Furthermore, the present results were strongly correlated with the earlier study on karanjin in an Alzheimer’s animal model. However, necessary in vivo studies, clinical trials, bioavailability, permeability and safe dose administration, etc. must be required to use karanjin as a potential drug against AD and PD treatment, where the in silico results are more helpful to accelerate the drug development.