Title:
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Solvothermal synthesis of novel inorganic materials
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Solvothennal and hydrothennal synthesis is widely applied in the generation of
. metastable crystalline phases, and is used in this work to prepare a range of novel
antimony-sulphide and rare-earth oxy-anion compounds in' the presence of linear,
branched and macrocycle amines. The new crystalline phases were characterised using
single-crystal X-ray diffraction, elemental analysis, diffuse reflectance spectroscopy
and SQUID magnetometry.
Transition-metals included in the reactions resulted in the fonnation of both
binary antimony-sulphide and ternary transition-metal-antimony-sulphide structures.
Binary phases include [Fe(en)3]Sb2Ss.0.55H20, [Fe(en)3hSb4Sg, [T(dien)2]Sb6SIO.xH20
(T= Ni, Co), [Co(en)3]SbgS13 and tNi(en)3]Sb12S19, where discrete [Sb2Sst units, SbS2chains,
Sb6SI0
6- and SbgS13
2- layers and a three-dimensional Sbl2Slt framework are
charge balanced by transition-I.l1etal-amine complexes. The ternary phases synthesised
using tris(2-aminoethyl)amine (tren) and diethylenetriamine (dien) include
[Cr(tren)]Sb4S7 chains with [Cr(tren)f+ pendent complexes, and [T(dien)hSblgS30[
T(dien)2] (T= Mn, Fe, Co), in which complex antimony-sulphide chains are bridged
via dimeric [T2S2] units to fonn novel layers. The transition-metal ions all exhibit
paramagnet~c behaviour and the band gaps of the phases were found to increase from
1.79(4) to 2.46(1) eV with increasing framework density.
The first examples of hydrothennal antimony-sulphide reactions using a
macrocycle, cyclam, as the structure directing agent resulted in the synthesis of novel ,
layered and three-dimensional phases of[cyclarnH2]Sb6SIO and [cyclamH2]Sb4S7. By
including transition-metal salts in the reaction mixture, it was possible to incorporate
transition-metal ions within the macrocyclic rings in [Ni(cyclam)]Sb4S7 and
[Co(cyclam)]x[cyclarnH2]J_xSb4S7, where the C02+ occupancy varies between
O.08
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