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Trilacunary Keggin‐Type POMs as Versatile Building Blocks for Lanthanoid Silicotungstates
Author(s) -
Ni Lubin,
Spingler Bernhard,
Weyeneth Stephen,
Patzke Greta R.
Publication year - 2013
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201201186
Subject(s) - polyoxometalate , chemistry , lanthanide , crystallography , thermogravimetric analysis , cyclic voltammetry , powder diffraction , electrochemistry , inorganic chemistry , catalysis , ion , organic chemistry , electrode
Three new lanthanoid‐substituted polyoxotungstates based on open Wells–Dawson fragments {[Ln 2 (H 2 O) 7 SiW 18 O 66 ] 10– [Ln = Eu III ( Eu‐1 and Eu‐2 ), Tb III ( Tb‐1 )]} and a new sandwich‐type polyoxometalate constituted of Keggin‐type monolacunary anions {[Eu(α‐SiW 11 O 39 ) 2 ] 13– ( Eu‐3 )} were obtained from the trilacunary Keggin POM Na 10 [SiW 9 O 34 ] · 23 H 2 O and lanthanoid salts as precursors. All compounds were comprehensively characterized by inductively coupled plasma (ICP) and thermogravimetric analyses and by FT‐IR and UV/Vis spectroscopy, as well as by powder X‐ray diffraction (PXRD) and single‐crystal X‐ray diffraction. Eu‐1 and Tb‐1 exhibit 3D architectures of dimeric [Ln 2 (H 2 O) 7 SiW 18 O 66 ] 10– units connected through Ln III linkers, whereas Eu‐2 displays a 2D sheet‐like framework. Eu‐3 exists in two enantiomeric forms, due to the C 2 symmetry of the central square‐antiprismatic EuO 8 polyhedron. The structure‐directing influence of the Ln cations on the emerging POM architectures is investigated in detail. Photoluminescence of Eu‐1 , Eu‐2 , Eu‐3 and Tb‐1 can be ascribed to the characteristic emissions of the Eu III and Tb III cations, respectively. The electrochemical properties of all compounds were investigated by cyclic voltammetry in sodium acetate buffer solution as supporting electrolyte. The magnetic susceptibility of Tb‐1 was studied in the temperature range between 5 and 300 K and indicated paramagnetic behavior.