Zn(II)–Siloxane Clusters as Versatile Building Blocks for Carboxylate-Based Metal–Organic Frameworks

Abstract

Siloxanes have long been known for their highly desirable properties suited for a wide range of practical applications; however, their utilization as modular building blocks for crystalline open frameworks has been limited. In this study, a simple solvothermal pathway has been found to synthesize unprecedented Zn­(II)–siloxane clusters supported by acetate ligands, [(RSiO2)8Zn8(CH3CO2)8] (R = Me or Ph). The same reaction using a dicarboxylate ligand such as 1,4-benzenedicarboxylate or 2,6-naphthalenedicarboxylate produces a new type of metal–organic framework, named SiMOF here, based on the [Si8Zn8] units. With the maximum connectivity of 8, the building block is shown to form topologically interesting structures such as octahedral supercages or uninodal 8-connected frameworks. All SiMOFs synthesized possess permanent porosity and high thermal stability and are naturally hydrophobic, as demonstrated by adsorptions of toluene, ethanol, methanol, and water vapor as well as water contact angle measurements. These promising characteristics for well-defined porous solids are attributed to metal-bound siloxane groups in the structural building units.

A Family of Hexacopper Phenylsilsesquioxane/Acetate Complexes: Synthesis, Solvent‐Controlled Cage Structures, and Catalytic Activity

“…Cu 6 -compounds include Si 6ligands, [104] while Cu 5 -compounds include Si 5 -ligands. [105] These results point at (i) significant potential of further implementation of carboxylate co-ligands for the molecular design of cage metallasilsesquioxanes [106] and (ii) potentially strong influence of particular systems of synthesis/crystallization on such design.…”

Fe(III)-Based Phenylsilsesquioxane/Acetylacetonate Complexes: Synthesis, Cage-like Structure, and High Catalytic Activity

“…Hybrid organo-inorganic metallacomplexes based on branched silsesquioxane ligands tend to form intriguing molecular geometries (cage-like metallasilsesquioxanes (CLMSs)). − The wide list of CLMSs’ functionalities spans antifungal activity, magnetic properties (including examples of single-molecule magnets , or spin glasses), and optical behavior − (including the first examples of CLMSs’ temperature sensor , ). Regarding materials science, the design of CLMS-based anode materials, flame retardants, and functional coordination polymers − should be mentioned. Several reviews reflect the CLMSs’ efficiency in different catalyzed reactions. − Among recent examples, we could cite their activity in the carboxylation of gaseous alkanes, deacetalization/deketalization-Knoevenagel reactions, Chan–Evans–Lam coupling, hydroboration of ketones, and oxidative amidation .…”