Rare earth arenedisulfonate metal-organic frameworks:: An approach toward polyhedral diversity and variety of functional compounds

Eight 2D and 3D metal-organic framework (MOF) rare earth naphthalenedisulfonates have been obtained. The different geometry of the naphthalenedisulfonic acids used as connectors [(1,5-NDS) and (2,6-NDS)] gives rise to the three new structure types. In Ln(OH)(1,5-NDS)H2O, LnPF-1 (lanthanide polymeric framework; Ln = La, Nd, Pr, Sm and Eu), the lanthanide ion is octacoordinated. Its 3D structure is formed by (Ln(2)O(14))-S-(Ln(2)O(14)) infinite chains, connected through complete NDS connectors. LnPF-2 (Ln = Nd), with the same empirical formula as the former, and the lanthanide in octa- and nonacoordination, owns an arrangement of sulfonate bridges and neodymium polyhedra that gives rise to a 2D structure. [Ln(5)(2,6-NDS)(3)(OH)(9)(H2O)(4)](H2O)(2), LnPF-3 (Ln = Nd, Eu), demonstrates that it is possible to obtain a 3D structure with (2,6-NDS), when a greater Ln/connector ratio is employed. It is worth pointing out the existence, in this latter family of compounds, of a mu(5)-OH group, whose hydrogen atom is very close to one-sixth Ln atom (distance Ln center dot center dot center dot H = 2.09 angstrom). The materials, with high thermal stability, act as active and selective bifunctional heterogeneous catalysts in oxidation of linalool yielding cyclic hydroxy ethers. The absence of any 3D Nd-Nd magnetic interaction is explained due to the inner nature of 4f orbitals of Nd3+, which do not favor the magnetic exchange. The influence of the polymeric frame matrix results in a better photoluminescence efficiency for NdPF-1.