Synthetic copper(II) oxalate, CuC2O4, was obtained in a precipitation reaction between a copper(II) solution and an aqueous solution of oxalic acid. The product was identified from its conventional X-ray powder patterns which match that of the copper mineral Moolooite reported to have the composition CuC2O4·0.44H2O. Time resolved in situ investigations of the thermal decomposition of copper(II) oxalate using synchrotron X-ray powder diffraction showed that in air the compound converts to Cu2O at 215 °C and oxidizes to CuO at 345 °C. Thermo gravimetric analysis performed in an inert Ar-gas reveals that the material contains no crystal water and reduces to pure Cu at 295 °C. Magnetic susceptibility measurements in the temperature range from 2 K to 300 K show intriguing paramagnetic behaviour with no sign of magnetic order down to 2 K. A crystal structure investigation is made based on powder diffraction data using one neutron diffraction pattern obtained at 5 K (λ = 1.5949(1) Å) combined with one conventional and two synchrotron X-ray diffraction patterns obtained at ambient temperature using λ = 1.54056, 1.0981 and λ = 0.50483(1) Å, respectively. Based on the X-ray synchrotron data the resulting crystal structure is described in the monoclinic space group P2₁/c (#14) in the P12₁/n1 setting with unit cell parameters a = 5.9598(1) Å, b = 5.6089(1) Å, c = 5.1138 (1) Å, β = 115.320(1)°. The composition is CuC2O4 with atomic coordinates determined by FullProf refinement of the neutron diffraction data. The crystal structure consists of a random stacking of CuC2O4 micro-crystallites where half the Cu-atoms are placed at (2a) and the other half at (2b) positions with the corresponding oxalate molecules centred around the corresponding (2b) and (2a) site positions, respectively. The diffraction patterns obtained for both kinds of radiation show considerable broadening of several Bragg peaks caused by highly anisotropic microstructural size and strain effects. In contrast to the water reported to be present in Moolooite, neither thermogravimetric nor the in situ thermal decomposition investigations and crystal structure analysis of the neutron diffraction data revealed any trace of water. An appendix contains details about the profile parameters for the diffractometers used at the European Synchrotron Radiation Facility and the Institute Max von Laue-Paul Langevin.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1039/c4dt01689k | DOI Listing |
BMC Plant Biol
January 2025
Plant Production Department, College of Food and Agricultural Sciences, King Saud University, P.O. Box. 2460, Riyadh, 11451, Saudi Arabia.
Background: The present research work was done to evaluate the anatomical differences among selected species of the family Bignoniaceae, as limited anatomical data is available for this family in Pakistan. Bignoniaceae is a remarkable family for its various medicinal properties and anatomical characterization is an important feature for the identification and classification of plants.
Methodology: In this study, several anatomical structures were examined, including stomata type and shape, leaf epidermis shape, epidermal cell size, and the presence or absence of trichomes and crystals (e.
Phytochemistry
January 2025
Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, People's Republic of China; Laboratory for Marine Drugs and Bioproducts, Qingdao Marine Science and Technology Center, Qingdao, 266237, People's Republic of China. Electronic address:
Two undescribed rearranged diterpenoids, lobopaucinoids A and B (1 and 2), along with thirteen undescribed lobane-type diterpenoids lobopaucinoids C-O (3-15) including a C (11) and two C (12 and 13) undescribed norditerpenoids, were isolated from the soft coral Lobophytum pauciflorum Ehrenberg (Sarcophytidae family) collected from Xisha Islands of the South China Sea. Additionally, two undescribed prenyleudesmane-type diterpenoids, lobopaucinoids P and Q (16 and 17), as well as two known lobane diterpenoids (18 and 19), were also obtained. Their structures were elucidated based on comprehensive spectroscopic data, Mosher's method, Mo(OAc) or Rh(OCOCF)-induced circular dichroism experiment, quantum chemical calculations, and single-crystal X-ray diffraction and literature comparison.
View Article and Find Full Text PDFJ Struct Biol
January 2025
Gavin Herbert Eye Institute - Center for Translational Vision Research, Department of Ophthalmology, University of California, Irvine, CA 92697, USA; Department of Chemistry, University of California, Irvine, CA 92697, USA; Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA. Electronic address:
Arrestins halt cell signaling by binding to phosphorylated activated G protein-coupled receptors. Arrestin-1 binds to rhodopsin, arrestin-4 binds to cone opsins, and arrestins-2,3 bind to the rest of GPCRs. In addition, it has been reported that arrestin-1 is functionally expressed in mouse cone photoreceptors.
View Article and Find Full Text PDFJ Biol Chem
January 2025
Department of Chemistry, The University of Texas at San Antonio, Texas 78249, United States. Electronic address:
MarE, a heme-dependent enzyme, catalyzes a unique 2-oxindole-forming monooxygenation reaction from tryptophan metabolites. To elucidate its enzyme-substrate interaction mode, we present the first X-ray crystal structures of MarE in complex with its prime substrate, (2S,3S)-β-methyl-L-tryptophan and cyanide at 1.89 Å resolution as well as a truncated yet catalytically active version in complex with the substrate at 2.
View Article and Find Full Text PDFJ Biol Chem
January 2025
Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4K1; Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada L8S 4K1. Electronic address:
Type VI secretion systems (T6SS) are dynamic protein nanomachines found in Gram-negative bacteria that deliver toxic effector proteins into target cells in a contact-dependent manner. Prior to secretion, many T6SS effector proteins require chaperones and/or accessory proteins for proper loading onto the structural components of the T6SS apparatus. However, despite their established importance, the precise molecular function of several T6SS accessory protein families remains unclear.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!