New class of Preyssler-lanthanide complexes with modified and extended structures tuned by the lanthanide contraction effect

A family of polyoxometalate compounds based on Preyssler anions and lanthanide cations, K(5)Na(5){Pr(4)(H(2)O)(12)(pydc)(4)}{Na(H(2)O)P(5)W(30)O(110)}]·46H(2)O (1, H(2)pydc = pyridine-2,6-dicarboxylic acid), Na(7){Pr(4)(H(2)O)(20)(pydc)(2)(Ac)}{Na(H(2)O)P(5)W(30)O(110)}]·23H(2)O (2), and Na(10)H(2) {Ln(2)(H(2)O)(10)(pydc)(2)}{Na(H(2)O)P(5)W(30)O(110)}]·XH(2)O (Ln = Sm 3, Eu 4, Gd 5; X = 11 for 3 and 5, 13 for 4), have been synthesized and characterized by elemental analysis and single crystal X-ray diffraction. Compound 1 exhibits a two-dimensional honeycomb layer which is built up from unique {Pr(4)} metallacycles and Preyssler anions. Remarkably, the strong involvement of the sodium countercations leads to the formation of a unique three-dimensional open architecture with one-dimensional channels. The 2D grid layer of compound 2 is constructed by the longest currently known rare-earth metal clusters {Pr(8)} and Preyssler anions. Isostructural compounds 3, 4, and 5, obtained by introduction of the intermediate lanthanide ions into the above reaction system, exhibit bisupporting {Ln(2)(H(2)O)(10)(pydc)(2)}{Na(H(2)O)P(5)W(30)O(110)}](12-) polyoxometalate cluster structures. The magnetic properties of compounds 1 and 2 and the luminescent properties of compounds 3 and 4 are discussed in this paper.