Rare Earth Arenedisulfonate Metal−Organic Frameworks:  An Approach toward Polyhedral Diversity and Variety of Functional Compounds

Abstract

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 (Ln2O14)-S-(Ln2O14) 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. [Ln5(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 mu5-OH group, whose hydrogen atom is very close to one-sixth Ln atom (distance Ln...H=2.09 A). 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.

Gd26Cluster Consisting of Distorted Cubane Cores: Synthesis, Structure and Heterogeneous Catalytic Epoxidation of Olefins

“…pounds have been used in several organic transformations [42] including the conversion of alkenes to their corresponding oxides in homogeneous media, [43] although rarely have they been used in epoxidation of olefins [44] or oxidation [45] of alkanes and sulfur compounds in heterogeneous media. The last decade witnessed an enormous effort to produce epoxides of electron deficient alkenes [46] and several approaches indicated that many lanthanide catalysts are reactive in epoxidation of α,β-unsaturated ketones, amides and esters.…”

Redes metalorgânicas e suas aplicações em catálise

“…Gandara et al 99 mostraram que MOFs de vários lantanídeos com o ligante naftalenodissulfonato foram ativas para a oxidação de linalool com peróxido de hidrogênio, produzindo compostos (óxidos, éteres) utilizados na indústria de perfumes, reação que necessita de catalisadores bifuncionais com sítios ácidos e redox. O mesmo grupo mostrou a atividade de MOFs de itérbio para a mesma reação e também para a hidrodessulfurização do tiofeno e oxidação de sulfetos, mostrando a importância da densidade de carga e do número de coordenação no átomo do lantanídeo para o desempenho catalítico 100 Em outro trabalho, com MOFs de Yb e ácido succínico, eles propuseram um mecanismo para a oxidação de sulfetos, baseado em evidências espectroscópicas, em que as espécies Yb-O-OH seriam responsáveis pela atividade catalítica.…”

Structural variety in ytterbium dicarboxylate frameworks and in situ study diffraction of their solvothermal crystallisation

“…6 Early work on catalysis by lanthanide MOFs studied Lewis acidity and redox activity for reactions such as acetalization of aldehydes and oxidation of sulphides, 7 cyanosilylation 8 and in bifunctional oxidation catalysts. 9 In more recent work in catalysis with lanthanide MOFs some examples of shape-selectivity are emerging when basic ligands are used. 10 For example, some have been developed as water-resistant and recyclable solid Lewisacids for various organic reactions, 11 while recently a multifunctional MOF based on a flexible dicarboxylate ligand and various lanthanides was produced with Lewis acidity and as a support for palladium for organic reductions.…”