Chemists Generate Framework for the Oxidation of Hydrocarbons

RUDN University chemists have produced new copper-containing metallasilsesquioxane frameworks. A few of them have proven to be effective catalysts for the oxidation of hydrocarbons. The results are published in Molecules.

What are Silsesquioxanes

Silsesquioxanes are a enormous team of organosilicon compounds. They are formed of a silicon and oxygen backbone, with the silicon atom having an organic substituent. Silsesquioxanes have the ability to bind metals to play the role of ligands, and metal-containing derivatives of silsesquioxanes are utilized in industrial chemistry for catalysis. Particularly, complexes of silsesquioxanes with metals catalyze the oxidation of hydrocarbons.

In a recent investigation, a RUDN College chemist made a series of new silsesquioxane complexes with copper and additional organic ligands, 8-hydroxyquinolines. Some of them evidenced to be efficacious catalysts.

“Silsesquioxane compounds are a type of bridge between organics and inorganics. They consist of a simply inorganic principal chain of silicon and oxygen; substituents at the silicon atom are accountable for the organic component. Silsesquioxanes are frequently considered as single molecular models for surface researches and for catalysis. Structural features of silsesquioxanes are utilized to produce organic-inorganic materials. One more essential feature of them is the role of ligands for metal complexes,” said Alexey Bilyachenko, Doctor of Sciences in Chemistry, Leading Scientist of the Joint Study Institute of Chemistry, RUDN University.

“At the same moment, in the composition of steel complexes silsesquioxanes have the ability to combine with additional organic ligands. Wondrously, the ligands of the very popular 8-hydroxyquinoline family have never been utilized to develop metallosilsesquioxane complexes. We examined the synthesis of the initial such compounds, examined their molecular and supramolecular structures, and likewise evaluated the properties of new compounds in the oxidation of hydrocarbons.”

Work done by scientists

Chemists synthesized a family of 11 compounds. All of them have a similar framework, a three-dimensional “skeleton” with two silsesquioxane and 2 8-hydroxyquinoline ligands, coordinating copper and alkali metal atoms (sodium, lithium, or potassium). The synthesis goes by self-assembly flow when easy reagents are transformed into a complex structure. RUDN College chemists explained in detail the structure of recent compounds and, after that, tested their catalytic abilities using the instance of hydrocarbon oxidation.

One of the gotten compounds turned out to be an efficacious catalyst in the oxidation of hydrocarbons and alcohols utilizing hydrogen peroxide. Chemists concluded that the essential mechanism in oxidation is radical, involving hydroxyl fragments.

“We showed the first instances of wireframe metallosilsesquioxanes containing 8-hydroxyquinoline ligands utilizing a convenient self-assembly technique. One of the structures showed high catalytic activity in the oxidation of hydrocarbons and alcohols. We concluded that oxidation proceeds with the participation of free hydroxyl radicals,” stated Alexey Bilyachenko, Doctor of Sciences in Chemistry, Leading Scientist of the Joint Research Institute of Chemistry, RUDN College.

Read the original article on PHYS.

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