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Microporous Rare Earth Coordination Polymers: Effect of Lanthanide Contraction on Crystal Architecture and Porosity
journal contribution
posted on 2002-05-18, 00:00 authored by A. Dimos, D. Tsaousis, A. Michaelides, S. Skoulika, S. Golhen, L. Ouahab, C. Didierjean, A. AubryA series of microporous coordination polymers of adipic (H2ad) and pimelic acids (H2pim)
with rare earth metals have been synthesized and structurally characterized. In the case of
adipic acid, two distinct structure types were isolated: structure type I with formula [Ln2(ad)3(H2O)4]6H2O, Ln = Ce3+, Pr3+, Nd3+, and strucure type II with formula [Ln2(ad)3(H2O)4]xH2O, Ln = Nd3+, Sm3+, Gd3+, Er3+, Yb3+. Type I compounds are isostructural to lanthanum
adipate (Inorg. Chem. 1998, 37, 3407) and contain interconnected channels filled with
hydrogen-bonded water molecules. The structure of type II polymers consists of interpenetrated (4,4) metal−organic networks. Channels along one crystallographic direction are
created by the interpenetration. The minimum width of the channels depends on the nature
of the metal incorporated in the framework. The passage from type I to type II structure is
ascribed to the well-known effect of lanthanide contraction. In the case of H2pim, one
compound of formula [La(pim)(Hpim)(H2O)]H2O was isolated. Channels, filled with water
molecules, are formed along one crystallographic direction. In all compounds, the water
molecules can be reversibly removed.