American Chemical Society
ic401143g_si_003.cif (19.33 kB)

Series of Uranyl-4,4′-biphenyldicarboxylates and an Occurrence of a Cation–Cation Interaction: Hydrothermal Synthesis and in Situ Raman Studies

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posted on 2016-02-19, 00:34 authored by Paula M. Cantos, Laurent J. Jouffret, Richard E. Wilson, Peter C. Burns, Christopher L. Cahill
Three uranium­(VI)-bearing materials were synthesized hydrothermally using the organic ligand 4,4′-biphenyldicarboxylic acid: (UO2)­(C14O4H8) (1); [(UO2)2(C14O4H8)2(OH)]·(NH4)­(H2O) (2); (UO2)2(C14O4H8)­(OH)2 (3). Compound 1 was formed after 1 day at 180 °C in an acidic environment (pHi = 4.03), and compounds 2 and 3 coformed after 3 days under basic conditions (pHi = 7.95). Coformation of all three compounds was observed at higher pHi (9.00). Ex situ Raman spectra of single crystals of 13 were collected and analyzed for signature peaks. In situ hydrothermal Raman data were also obtained and compared to the ex situ Raman spectra of the title compounds in an effort to acquire formation mechanism details. At pHi = 4.00, the formation of 1 was suggested by in situ Raman spectra. At an increased pHi (7.90), the in situ data implied the formation of compounds 1 and 3. The most basic conditions (pHi = 9.00) yielded a complex mixture of phases consistent with that of increased uranyl hydrolysis.