Total electron scattering cross sections for carbon dioxide at low electron energies

Absolute total electron scattering cross sections for carbon dioxide have been measured at low electron energies using a photoelectron source. The measurements have been carried out at 27 electron energies varying from 0.91–9.14 eV with an accuracy of ±3%. The cross sections obtained in the present experiment have been compared with other measurements and theoretical computations.     

Isomeric pyrazolo­[3,4-d]­pyrimidine-based mol­ecules: disappearance of dimerization due to interchanged substitutions

In 5-benzyl-1,7-di­methyl-4,5,6,7-tetra­hydro-1H-pyrazolo­[3,4-d]­pyrimidine-4,6-dione, C₁₄H₁₄N₄O₂, which crystallizes in space group P, weak intermolecular C—H⋯O hydrogen bonds generate dimers. The isomeric compound 1-benzyl-5,7-di­methyl-4,5,6,7-tetra­hydro-1H-pyrazolo­[3,4-d]­pyrimidine-4,6-dione, C₁₄H₁₄N₄O₂, crystallizes in space group P2₁/n, and shows no such dimerization. Instead, it exhibits C—H⋯π interactions with the phenyl ring. In both structures, the mol­ecules are linked by aromatic π–π-stacking interactions.     

Synthesis, characterisation and evaluation of polydithiocarbamate resin supported on macroreticular styrene-divinylbenzene copolymer for the removal of trace and heavy metal ions

A new chelating resin was synthesised by the modification of styrene-divinylbenzene (2%) copolymer and incorporation of dithiocarbamate groups. The polydithiocarbamate resin was characterised by elemental analysis, thermal studies and IR studies. The analytical characteristics of the sorbent were established and optimum sorption conditions for Cu, Ni, Pb, Fe, As and Mn determined. The total sorption capacity of the resin was 37 mg g⁻¹ for Ni(II), 35 mg g⁻¹ for Cu(II), 29 mg g⁻¹ for Fe(III) and 23 mg g⁻¹ for Pb(II). The optimum pH for the removal of metal ions was 3-5 for Ni(II), 5 for Cu(II), 4 for Fe(III) and 4-5 for Pb(II). High sorption capacity was observed when compared with other conventional chelating polymers. The sorption kinetics was fairly rapid, as apparent from the loading half time t_1/2 values, indicating a better accessibility of the chelating sites.     

Synthesis, Characterization and Antibacterial Activity of Some Transition Metal cis-3,7-dimethyl-2,6-octadiensemicarbazone Complexes

The synthesis and characterization of some transition metal cis-3,7-dimethyl-2,6-octadiensemicarbazone (CDOSC) complexes are reported. The ligand CDOSC yields: [ML₂ Cl₂] and [ML₂ Cl₂] Cl type complexes, where M = Cr^III, Mn^II, Fe^III, Co^II, Ni^II, Cu^II, Zn^II, Cd^II and Hg^II, L = CDOSC. Structures of the complexes were determined using elemental analysis, molar conductivity, magnetic measurements, i.r. and electronic, as well as n.m.r spectra. CDOSC acts as a bidentate ligand in all the complexes. All the newly synthesized metal complexes, as well as the ligand, were screened for their antibacterial activity. All the complexes exhibit strong inhibitory action against Gram (+) bacteria Staphylococcus aureus and Gram (−) bacteria Escherichia coli. The antibacterial activities of the complexes are stronger than those of the ligand CDOSC itself.     

Asymmetric synthesis of (+)-stagonolide C and (−)-aspinolide A via organocatalysis

A new enantioselective synthesis of two important fungal metabolites, (+)-stagonolide C and (?)-aspinolide A, has been described from readily available raw materials. Proline catalyzed asymmetric α-aminooxylation and Jorgensen’s epoxidation of aldehydes are the key reactions employed in the introduction of chirality. The formation of the 10-membered lactone core structure was finally accomplished via Steglich esterification and ring closing metathesis reactions.