The role of As2O3 on the stability and some physical properties of PbO-Sb2O3 glasses

PbO-Sb₂O₃ glasses added with different concentrations of As₂O₃ (10-55 mol%) were prepared to understand their IR spectra, elastic properties (Young's modulus E, Shear modulus G, microhardness H), optical absorption and dielectric properties (constant ε, loss tan δ, ac conductivity σ_ac over a moderately wide range of frequency and temperature and breakdown strength in air medium at room temperature). Results have indicated that the structure of the PbO-Sb₂O₃-As₂O₃ glass is more rigid when the concentration of As₂O₃ is around 40 mol%.     

Synthesis and spectral studies on some tetrahydrobenzoxanthen-11-ones: crystal and molecular structure of 9,9-dimethyl-12-(2-nitrophenyl)-8,9,10,12-tetrahydrobenzo[<Emphasis Type="Italic">a</Emphasis>]xanthen-11-one

A series of 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-ones have been synthesized by the multicomponent reaction (MCR) of β-naphthol, aryl aldehydes, and dimedone by using BF₃:OEt₂ as a catalyst. The derived compounds have been analyzed by IR, NMR (1D and 2D), and mass spectra. The single crystal X-ray structural analysis of 9,9-dimethyl-12-(2-nitrophenyl)-8,9,10,12-tetrahydrobenzo[a]-xanthen-11-one evidences the envelope conformation of the cyclohexane ring and the pyran ring tends to adopt flattened-boat conformation.     

Synthesis of β‐Hydroxy α‐Sulfanyl Esters by Using Nanocrystalline Magnesium Oxide

Aldol‐type reaction between electron deficient aldehydes and sulfonium salts to afford the corresponding β‐hydroxy α‐sulfanyl esters in moderate‐to‐good yields by using nanocrystalline MgO is described. The sulfanyl group is a useful group for further transformations in organic synthesis. Low R_f‐value isomer is anti‐configured as revealed by X‐ray diffraction study and consistent with the assignment of ¹H‐NMR spectrum.     

Sulfate anion helices formed by the assistance of a flip-flop water chain

A flip-flop extended water structure assists the formation of sulfate anion helices (both left- and right-handed) in a crystalline hydrate of a simple organic-inorganic compound [C6H10N2]SO4. 1.5H2O (1).     

Spectral and X-ray Diffraction Studies of <Emphasis Type="Italic">N</Emphasis>-(2-Nitrophenyl)-5-Phenyl-1,3,4-Oxadiazole-2-Amine

Abstract  

Thiosemicarbazides and their derivatives are well known for their use in biological activity and many applications in pharmaceutical and industrial fields. The cyclization of 1-benzoyl-4-(2-nitrophenyl)-3-thiosemicarbazide (BNPTSC) in dimethylformamide (DMF) medium furnished N-(2-nitrophenyl)-5-phenyl-1,3,4-oxadiazole-2-amine (NPPOA). The chemical structure of the above substituted 1,3,4-oxadiazole has been assigned by IR, mass and X-ray diffraction studies. The XRD studies reveal the presence of four types of hydrogen bonds (N–H···O, N–H···N, C–H···O, C–H···N) in the crystal packing. The crystal system was found to be orthorhombic with a space group Pca2(1) and the unit cell dimensions are: a = 26.873(3) ?, b = 6.0827(7) ?, c = 7.8502(10) ?, α = 90°, β = 90°, γ = 90° and Z = 4.     

Single crystal X-ray analysis of isomeric 2-(2,4,4-trimethyl-3,4-dihydro-2h-benzo[h]× chromen-2-yl)-1-naphthyl acetate and 3-(2,4,4-trimethyl-3,4-dihydro-2H-benzo[g]× chromen-2-yl)-2-naphthyl acetate

Single crystal X-ray structure characterization of isomeric 2-(2,4,4-trimethyl-3,4-dihydro-2H-benzo[h]chromen-2-yl)-1-naphthyl acetate (1) and 3-(2,4,4-trimethyl-3,4-dihydro-2H-benzo[g]chromen-2-yl)-2-naphthyl acetate (2) is described. Compound 1 crystallizes in the centrosymmetric monoclinic space group P2₁/c with all atoms situated in general positions. Isomeric compound 2 crystallizes in the centrosymmetric triclinic space group P-1 and its structure consists of two crystallographically independent molecules with all atoms located in general positions. In addition to intramolecular C-H??O bonding, 2 is involved in two intermolecular C-H??O interactions resulting in a one-dimensional H-bonded network.     

Synthesis,spectroscopic properties,structural characterization and electrochemistry of mixed ligand complexes of copper(I) halide with PPh3 and naphthylazoimidazole

The reaction of CuX (X = Cl, Br, I) with a mixture of PPh₃ and 1-alkyl-2-(naphthyl-α/β-azo)imidazole has synthesized mixed ligand complexes of the composition, [Cu(α/β-NaiR)(PPh₃)X]. The spectroscopic characterization (IR, UV–Vis, ¹H NMR) supports this formulation. The single crystal X-ray diffraction study of [Cu((α-NaiMe)(PPh₃)I] (7a) (α-NaiMe = 1-methyl-2-(naphthyl-α-azo)imidazole) shows a distorted tetrahedral geometry about Cu(I). Cyclic voltammograms of the complexes show a high potential Cu(II)/Cu(I) couple and azo reductions. The [Cu(α/β-NaiR)(PPh₃)I] complexes show an additional oxidative response at 0.4 V that is assigned to I/I⁻ A sharp anodic peak at ∼−0.2 V is assigned to the oxidation of metallic Cu, deposited on electrode surface upon scanning to the negative side of the SCE. DFT and TD-DFT computations of [Cu((α-NaiMe)(PPh₃)I] (7a), [Cu((α-NaiMe)(PPh₃)I]⁺ (7a⁺) and [Cu((α-NaiMe)(PPh₃)I]⁻ (7a⁻) were carried out to examine the electronic configuration and to explain the spectral and redox properties of the complexes.     

Synthesis, spectroscopy, thermal studies and supramolecular structures of two new alkali-earth 4-nitrobenzoate complexes containing coordinated imidazole

The reaction of hydrated magnesium or calcium 4-nitrobenzoate (4-nba) generated in situ, with imidazole (Im) results in the formation of the complexes [Mg(H₂O)₂(Im)₂(4-nba)₂] 1 and [Ca(H₂O)₃(Im)(4-nba)₂]·Im 2, which exhibit the same metal:4-nba:Im ratio but different degrees of hydration. Complex 1 crystallizes in the triclinic Pī space group and the Mg atom is located on an inversion centre, while 2 crystallizes in the monoclinic P2₁/c space group and all atoms are located in general positions. In 1 the Im ligands, which are trans to each other, are coordinated to Mg, while 2 contains coordinated as well as free Im. The monodentate 4-nba ligands are disposed trans to each other in 1, while they adopt a cis orientation in 2 resulting in different supramolecular structures. Complex 1 exhibits two types of H-bonding interactions namely O-H···O and N-H···O, while in 2 three varieties of H-bond, viz. O-H···O, N-H···O and O-H···N are observed. The Im ligand ligand functions as a bifurcated H-bond donor in 1 while the O atom of the nitro group functions as a H-bond acceptor. In contrast, the nitro group in 2 is not involved in any H-bonding interactions. The free Im in 2 functions as a bifurcated acceptor and forms an extended chain linking adjacent complex molecules. The chains thus formed are further cross-linked with the aid of H-donor bonds from both the free as well as the coordinated Im. Both 1 and 2 exhibit π-π stacking interactions. Complex 1 is thermally more stable as compared to 2, and both complexes can be dehydrated to the corresponding anhydrous complexes by heating at 140 and 100°C respectively. At elevated temperatures, both the complexes can be pyrolysed to the corresponding oxide. The anhydrous complexes can be rehydrated to obtain the starting hydrated materials.     

Electron Capture Probabilities in105Ag

TheK-electron capture probabilities for the 1/2^? → 3/2^? and 1/2^? → 1/2⁺ transitions in the decay of¹⁰⁵Ag were measured for the first time using the sum coincidence method. The experimental P_K values were estimated to be 0.824 ± 0.042 and 0.851 ±0.046 for the allowed and first-forbidden beta transitions, respectively in agreement with the theory. The P_L experimental values to these two levels were also computed using the experimental P_L/P_K values reported by earlier authors. These results are also found to be consistent with the theoretical P_L values.