| dc.description.abstract | A neodymium oxalatophosphonate and the praseodymium
analogue, Na[Ln3(H2O)4(C2O4)4(CH3PO3)]·2H2O [Ln = Nd (A) and Pr
(B)], have been synthesized by hydrothermal method and characterized
by single-crystal X-ray diffraction and thermogravimetric analysis. We
studied the photoluminescence spectra as well as the magnetic
properties of the both compounds. The structure consists of layers built
of tetramers of edge- and face-sharing LnO9 polyhedra connected by
oxalate and methylphosphonate units, which are linked by zigzag
infinite chains of oxalate-bridged LnO9 polyhedra to form a 3-D
framework. They are the first examples of lanthanide
oxalate-methylphosphonate. The μeff of Nd is 3.663 μb and the μeff of Pr
is 3.795 μb; both are very close to the theoretical values. The Nd
compound displays characteristic emission bands in the near IR region
with lifetime 1.6 ± 0.1 μs. Luminescence of the Pr compound consists
of many emission bands at 480-760 nm with lifetime 1.7 ± 0.1 μs and
2.6 ± 0.1 μs, respectively. The lifetimes of both compounds are much
shorter than the expected values due to the quenching effects of water
molecules in the structure. Crystal data for the Nd compound follow:
triclinic, P`1 (No. 2), a = 9.0682(2) Å, b = 9.5114(3) Å, c = 14.0066(4)
Å, a = 74.975(2)°, b = 86.534(2)º, g = 82.725(2)°, and Z = 2. Crystal
data for the Pr compound are the same as those for the Nd compound
except a = 9.125(1) Å, b = 9.549(1) Å, c = 14.073(2) Å, a = 75.086(2)°,
b = 86.611(2)º, and g = 82.545(2)°. | en_US |