Synthesis and Structural Characterization of ... - Jacobs University

Amal H. Ismail
Ph.D. Thesis Abstract
Abstract
Polyoxometalates (POMs) represent a large class of nanosized metal-oxo anions. POMs are
remarkable not only in terms of molecular and electronic structural versatility, but also due to
their reactivity and relevance in fields such as photochemistry, analytical chemistry, clinical
chemistry, magnetism, catalysis, biology, medicine and materials science. Lanthanidecontaining
POMs have been investigated less than those containing 3d-transition metals. The
former have shown interesting properties in the areas of photoluminescence, catalysis,
electrochemistry, and magnetism.
Chapter I contains an extensive introduction to the class of POMs. Chapter II describes the
synthetic procedures for some POM precursors and presents the different experimental
techniques used for the characterization of the products. Chapter III comprises the lanthanidecontaining
polyoxotungstates results, divided into two sections, the lanthanide
isopolytungstates and the lanthanide heteropolytungstates. In the first section, the polyanions
[Ln 2 (H 2 O) 10 W 22 O 71 (OH) 2 ] 8− (Ln = La, Ce, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y) {Ln 2 W 22 } and the
V-shaped polyanions [Ln 2 (H 2 O) 10 W 28 O 93 (OH) 2 ] 14−
(Ln = Sm, and Eu) {Ln 2 W 28 } were
discussed. The {Ln 2 W 22 } family consists of the [H 2 W 22 O 74 ] 14− fragment and two
{Ln(H 2 O) 5 } 3+ supporting units while the {Ln 2 W 28 } consists of the [H 2 W 28 O 95 ] 20− unit and
two {Ln(H 2 O) n } 3+
supporting groups. The [H 2 W 22 O 74 ] 14− cluster is made up of two
undecatungstate fragments while the [H 2 W 28 O 95 ] 20− cluster consists of two undecatungstate
and a hexatungstate fragment. In the second section, the mono- and di-lanthanide derivatives
of the tungstoarsenates(III) [Yb(H 2 O) 2 K(H 2 O) 2 As 2 W 19 O 67 (H 2 O)] 10− {YbAs 2 W 19 };
[La 2 (H 2 O) 6 As 2 W 19 O 67 (H 2 O)] 8− {La 2 As 2 W 19 }, the mono- and di-lanthanide derivatives of the
tungstoantimonates(III) [Ln(H 2 O) 3 Sb 2 W 21 O 72 (OH))] 10− (Ln = Yb, Lu, Y) {LnSb 2 W 21 };
[Ln 2 (H 2 O) 6 Sb 2 W 20 O 70 )] 8−
(Yb, Lu, Y) {Ln 2 Sb 2 W 20 }, and the acetate sandwich-type
tungstogermanates [(Ln(GeW 11 O 39 )(H 2 O)) 2 (-CH 3 COO) 2 ] 12− (Ln = Eu, Gd, Lu) have been
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