Organic Ligands Made Porous: Magnetic and Catalytic Properties of Transition Metals Coordinated to the Surfaces of Mesoporous Organosilica

Abstract

Inorganic solids with porosity on the mesoscale possess a high internal surface area and a well‐accessible pore system. Therefore, it is a relevant task to equip the surfaces of such materials with a maximum density of various organic functional groups. Among these functions it is the capability of coordinating to metal species as a ligand that is of extraordinary importance in many areas, for example, in catalysis. This paper describes how prominent ligands containing donor functions such as carboxylic, thio, chelating, or amine groups can be obtained in the form of nanoporous organosilica materials. The coordination of metal centers such as CoII, MnII, VIV, or PtIV is studied in detail. The magnetic properties of the corresponding materials and some applications in catalysis are reported. A quantitative determination of the surface density of donor atoms by distance measurements using EPR spectroscopy is shown.

Functional Materials: From Hard to Soft Porous Frameworks

“…[181] The synthesis of PMOs containing benzoic acid, dithiobenzoic acid, acetylacetonate, and aniline groups was also described. [182] Bifunctional PMOs that contain both aniline and benzoic acid have been prepared and the cooperativity of the two groups in a two-step catalytic process was demonstrated. [183] A PMO with interesting optical properties was synthesized from a tetraphenylpyrene-containing organosilane precursor.…”

Periodic Mesoporous Organosilica Derivatives Bearing a High Density of Metal Complexes on Pore Surfaces

“…[6] Recently, Polarz and co-workers reported the coordination of transition-metal cations to Ph-PMOs functionalized with carboxylic, dithiocarboxylic, acetylacetonate, and amine groups. [7] This approach has the advantage that bulky metal complexes can be densely and selectively integrated on the pore surface of highly ordered PMOs. However, these metal complexes attached to a PMO framework have limited functionalities mainly because of the poor ligand ability of these PMOs.…”

Funktionsmaterialien: von harten zu weichen porösen Netzwerken

“…[181] Des Weiteren wurden PMOs mit Benzoesäure-, Dithiobenzoesäure-, Acetylaceton-und Anilinfunktionen in den Porenwänden beschrieben. [182] Difunktionelle PMOs mit sowohl Anilin-als auch Benzoesäuregruppen in den Porenwänden zeigten einen kooperativen Effekt der beiden Gruppen in einer Zwei-Stufen-Katalyse. [183] Ein PMO mit interessanten optischen Eigenschaften wurde aus einer Tetraphenylpyren-verbrückten Organosilicatvorstufe hergestellt.…”