Molecular Geochemistry at Umeå University
connecting atoms with mountains
News from the Lab
Emma Westling, Lisa Bryggman and Niklas Viklund from Nolaskolan in Örnsköldsvik brought in soil samples for Cesium-137 analysis. Many thanks to Peder Arvidsson from the University Hospital of Umeå (Center for medical technique and radiation physics) for providing access to his laboratory and hosting the students.
The Swedish Research Council (Vetenskapsrådet, VR) has awarded Michael Holmboe a 4-year research project grant, for a project focusing on adsorption of biogeochemical organics to clays and similar minerals!
Hydrocarbon-soluble, hexaanionic fulleride complexes of magnesium
Chem. Sci., 2019, 10, 10755-10764. Link
Samuel R. Lawrence, C. André Ohlin, David B. Cordes, Alexandra M. Z. Slawin, Andreas Stasch
Abstract: The reaction of the magnesium(I) complexes [{( Arnacnac)Mg}2], ( Arnacnac = HC(MeCNAr)2 , Ar =Dip (2,6-iPr2C6H3), Dep (2,6-Et2C6H3), Mes (2,4,6-Me3C6H2), Xyl (2,6-Me2C6H3 )) with fullerene C60 afforded a series of hydrocarbon-soluble fulleride complexes [{(Arnacnac)Mg}nC60], predominantly with n = 6, 4 and 2. 13C{1H} NMR spectroscopic studies show both similarities (n = 6) and differences (n = 4, 2) to previously characterised examples of fulleride complexes and materials with electropositive metal ions. The molecular structures of[{(Arnacnac)Mg}nC60] with n = 6, 4 and 2 can be described as inverse coordination complexes of n [(Arnacnac)Mg]+ ions with C60n- anions showing predominantly ionic metal-ligand interactions, and include the first well-defined and soluble complexes of the C606- ion. Experimental studies show the flexible ionic nature of the {(Arnacnac)Mg}+····C606- coordination bonds. DFT calculations on the model complex [{(Menacnac)Mg}6C60] (Menacnac = HC(MeCNMe)2) support the formulation as an ionic complex with a centralC606- anion and comparable frontier orbitals toC606- with a small HOMO-LUMO gap. The reduction of C60 to its hexaanion gives an indication about the reducing strength of dimagnesium(I) complexes.
Deconvolution of Smectite Hydration Isotherms
Microwave Synthesis of Alkali-Free Hexaniobate, Decaniobate, and Hexatantalate Polyoxometalate Ions
in Eur. J. Inorg. Chem., 2019, 35, 3913-3918. Link
M. A. Rambaran, M. Pascual-Borràs and C. A. Ohlin
Abstract: Microwave synthesis of polyoxoniobates and -tantalates circumvents the prolonged heating required by conventional hydrothermal methods, while providing comparable or greater yields. Microwave irradiation allows synthesis of polyoxoniobates from anhydrous niobium pentoxide, in lieu of niobic acid and sets the precedent for the discovery of new polyoxoniobates and -tantalates.
A postdoctoral fellowship in spectroscopic studies of mercury interactions with bacterial surfaces is available in Erik Björn’s group. See https://www.umu.se/en/work-with-us/fellowships-and-grants/6-1298-19/
Michael Holmboe’s collaboration with researchers (Ruth Tinnacher, CSUEastBay and Christophe Tournassat, LBNL, BRGM) in the US focusing on uranyl complex – clay transport and interactions was highlighted in the evening newspaper Expressen, forskning.se and (initially) by the faculty news.
The study is a collaboration with the group of Khalil Hanna (Rennes University)
Lian Zhou, Sébastien Martin, Wei Cheng, Laurent Lassabatere, Jean-François Boily, Khalil Hanna (2019) Water flow variability affects adsorption and oxidation of ciprofloxacin onto hematite. Environ. Sci. Technol. (accepted)
In collaboration with Hongfei Wang (Fudan University) and other current and former Pacific Northwest National Laboratory scientists, we used Sum Frequency Generation Vibrational Spectroscopy (SFG-VS) and molecular model to provide new insight on the orientation and hydrogen bond populations of nanometric water films on sapphire (alpha-Al2O3) surfaces:
