Growth-modulating agents for the synthesis of Al-MOF-type materials based on assembled 1D structural subdomains.

Novel aluminium MOF-type materials structured by 1D subdomains, such as organic-inorganic nanoribbons, were synthesized by modifying the conditions of solvothermal synthesis and the nature of the solvents in the presence of aryl monocarboxylate linkers with long alkyl chains, which acted as growth-modulating agents. Specifically, three different families of materials were prepared with various morphological characteristics: (i) isoreticular MIL-53(Al)-type materials, (ii) mesoscopic metalorganic structures and (iii) lamellar aluminium MOFs. The length of the alkyl chain in the aryl linker and the hydrophobic/hydrophilic nature of the solvothermal synthesis media determined the structuration level that was achieved. The derived Al-MOFs are active and stable catalysts for the synthesis of fine chemicals. This was illustrated by the efficient synthesis of 2,3-dihydro-2,2,4-trimethyl-1H-1,5-benzodiazepine.

Bimetallic nanosized solids with acid and redox properties for catalytic activation of C-C and C-H bonds.

A new approach is presented to form self-supported bimetallic nanosized solids with acid and redox catalytic properties. They are water-, air- and H2-stable, and are able to activate demanding C-C and C-H reactions. A detailed mechanistic study on the formation of the Ag-Fe bimetallic system shows that a rapid redox-coupled sequence between Ag+, O2 (air) and Fe2+ occurs, giving monodisperse Ag nanoparticles supported by O-bridged diatomic Fe3+ triflimides. The system can be expanded to Ag nanoparticles embedded within a matrix of Cu2+, Bi3+ and Yb3+ triflimide.

Synthesis, characterization, and framework heteroatom localization in ITQ-21.

ITQ-21 has been synthesized in a wide range of compositions. By rationally modifying the synthesis variables and zeolite composition, it is possible to fine-tune the crystallite size from nanocrystals (<80 nm) up to microns and to avoid the competition of other phases such as CIT-5, SSZ-24, or a laminar phase that can also be synthesized with the same organic structure directing agent. By means of XRD and (19)F MAS NMR, Ge and Si have been localized among the different crystallographic positions, and it is shown that Ge preferentially occupies T1 positions at the D4R cages, avoiding formation of Ge-O-Ge pairs. However, at high Ge loadings (Si/Ge = 1.7), a new (19)F MAS NMR signal at -14 ppm has been observed and assigned to the presence of Ge-O-Ge in Ge-rich D4R cages. Energetic configurations obtained by theoretical calculations fully agree with experimental observations, with the following increasing order in energy for Ge substitution: T1 < T2 < Ge-O-Ge in T1 < T3.