A method to control the arrangement of various metal elements in MOFs at atomic and mesoscopic scales is described.

Two new layered polymeric frameworks have been synthesized under different hydrothermal conditions and characterized by single-crystal X-ray diffraction, thermal analysis, and variable temperature-Fourier Transform Infrared Spectroscopy (VT-FTIR). The compound I, with formula [Er(2)(dms)(3)(H(2)O)(4)], has a triclinic cell with parameters a = 5.8506 A, b = 9.8019 A, c = 11.9747 A, alpha = 70.145 degrees , beta = 80.234 degrees , and gamma = 89.715 degrees , and the compound II, [Er(2)(dms)(3)(H(2)O)], is monoclinic and its cell parameters are a = 11.1794 A, b = 18.2208 A, c = 12.7944 A, beta = 112.4270 degrees , where dms = 2,2-dimethylsuccinate ligand. A theoretical study including energy calculations of the dms conformers was carried out at the Density Functional Theory (DFT-B3LYP) level of theory, using the 6-311G* basis set. Further calculations of the apparent formation energies of I and II crystalline structures were performed by means of the periodic density functional theory, using DF plane-waves. The analysis of the structural features, theoretical relative stabilities, and the influence of synthesis conditions are presented here. The heterogeneous catalytic activity of the new compounds is tested and reported.

Three new families of compounds were obtained as pure phases, with different lanthanide cations and the 3,5-disulfobenzoic acid (3,5-DSB). The hydrothermal synthesis conditions' influence on structural type obtained was studied. The structural type RPF-21 corresponds to the compound [Ln(3,5-DSB)(H 2 O) 5 ] (Ln = La, Pr, Nd); RPF-22 to the compound [Ln(3,5-DSB)(H 2 O) 3 ] (Ln = La, Pr, Nd, Sm, and Eu), and RPF-23 to the compound [Ln 3 (3,5-DSB) 2 (OH) 3 (H 2 O) 3 ] (Ln = Pr, Nd, and Eu). The dimensionality and the topology of the compounds are determined by the sulfonate group coordination modes; RPF-23 presents a new type of topology. Computational studies have determined the relative energies for those compounds that coexist under certain hydrothermal conditions, and they have brought some light to the thermodynamic or kinetic control that drives each reaction. The new materials were tested as catalysts in cyanosilylation reaction (CSR) of aldehydes under solvent-free conditions. The three of them catalyze the CSRs within 4 h, and a remarkable difference in activity is found between RPF-21 and the other two materials. The catalytic activity mainly depends on the network structure, with very little influence of the lanthanide cation. The mechanism includes, probably, a displacement of the catalyst labile water molecules by aldehyde before catalyst's activation and reaction.

RPF-4 is a family of polymeric frameworks prepared with rare-earth elements and the versatile ligand 4,4'-(hexafluoroisopropylidene)bis(benzoic acid). We have found that during the synthesis procedure up to three different polymorphs can be obtained. Their crystal structures are here presented. The three networks have unusual topologies, the three being uninodal penta-coordinated, two of them unknown up to now, and the other named hxg-d-5-Imma. They are here described and compared. DFT calculations of the relative energies for the three polymorphs show that the most often obtained structure is a metastable phase, which appears to be, next to others, thermodynamically more stable.