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Designer ligands for oxidative bond activation catalysis

English title Designer ligands for oxidative bond activation catalysis
Applicant Albrecht Martin
Number 182663
Funding scheme Project funding (Div. I-III)
Research institution Departement für Chemie, Biochemie und Pharmazie Universität Bern
Institution of higher education University of Berne - BE
Main discipline Inorganic Chemistry
Start/End 01.01.2019 - 31.12.2022
Approved amount 1'000'000.00
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All Disciplines (2)

Discipline
Inorganic Chemistry
Organic Chemistry

Keywords (9)

water oxidation; reaction mechanism; N-donor ligands; late transition metals; first row transition metals; ligand tailoring; ligand cooperatively; oxidation catalysis; mesomer isomerization

Lay Summary (German)

Lead
Katalytische Prozesse sind zentral für einen nachhaltigeren Umgang mit Resourcen, da katalytische Reaktionen viel Energie sparen und Abfall verringern, und meist mehrere Reaktionen in einen einzigen Schritt komprimieren. Ein in der Katalyse bisher nur spärlich untersuchtes Gebiet ist die Oxidation, insbesondere wegen derer Komplexität und den hohen Anforderungen an die Stabilität des Katalysators. Allerdings bietet die Oxidations-Katalyse hervorragende Perspektiven zur Synthese von hochwertigen Produkten und für die künstliche Photosynthese zur Nutzung von erneuerbaren Energien.
Lay summary

Inhalt und Ziel des Forschungsprojekts

Unser Forschungsprogramm will robuste und präzis definierte Katalysatoren herstellen, die die kontrollierte Oxidation von Substraten ermöglichen. Die Grundlage zum Erreichen dieses Ziels bilden spezielle Metall-Verbindungen, in denen das Metall von Liganden in seiner Reaktivität unterstützt wird. Die von uns in bisherigen Arbeiten entwickelten Liganden sind dynamisch, und können so einen Teil der Komplexität der Oxidationsreaktion vereinfachen. Konkret werden wir i) spezifische Ligand-Serien herstellen, ii) diese mit Nobel-metallen für effizientere Oxidationen kombinieren, und iii) mit diesen Liganden einfach zugänglichen Metallen zu wertvolle Katalaysatoren umwandeln.

 

Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojekts

Unser Projekt wird neue Methoden für die nachhaltigere Herstellung von wertvollen Substanzen verfügbar machen. Von besonderem Interesse sind effiziente Methoden für die Oxidation von Wasser, momentan der Engpass, um Sonnen- und Windenergie in chemischen Bindungen zu speichern. Diese Form von Energiespeicherung ist zentral für eine von fossilen Brennstoffen und Nuklearenergie unabhängige(re) Gesellschaft besonderem Interesse sind effiziente Methoden für die Oxidation von Wasser, momentan der Engpass, um Sonnen- und Windenergie in chemischen Bindungen zu speichern. Diese Form von Energiespeicherung ist zentral für eine von fossilen Brennstoffen und Nuklearenergie unabhängige(re) Gesellschaft.

Direct link to Lay Summary Last update: 04.01.2019

Responsible applicant and co-applicants

Employees

Associated projects

Number Title Start Funding scheme
162868 Mesoionic ligands as versatile promoters for energy-relevant oxidation catalysis 01.12.2015 Project funding (Div. I-III)
198127 High-resolution Electron Impact Ionization Mass Spectrometer equipped with a Gas Chromatograph 01.01.2021 R'EQUIP

Abstract

Oxidation catalysis is considerably less developed than for example metathesis, cross-coupling, or hydrogenation and related reactions. In parts, this lack is due to the mechanistic complexity of most oxidative transformations, and also due to the generally harsh reaction conditions required for oxidation reactions. Moreover, such redox reactions require the stabilization of the catalytically active center in multiple oxidation states. We recently demonstrated that N-donor ligands containing a pyridylidene substituent (pyridylidene amides, PYAs, and pyridylidene amines, PYEs) display high flexibility in stabilizing various oxidation states and are robust ligands, hence imparting promising properties for application in redox catalytic transformations. Specifically, these ligands undergo mesomeric interconversion between a -acidic neutral state and a -basic zwitterionic state featuring an anionic N-donor site. This unique donor-flexible behavior is ideal for the stabilization of both high- and low-valent metal centers on a redox catalytic cycle.This project aims at exploiting such flexible N-donor ligand systems to discover and develop highly active oxidation catalysts for challenging bond activation. In a foundational work package, the synthetic versatility and easy accessibility of these ligands will be demonstrated by preparing a diverse library of ligand scaffolds, which offer steric and electronic fine-tuning of the catalytically active site. Metalation is facilitated by the kinetic lability of the N-bound hydrogen, which provides access to the free base ligand. Catalytic application will be exploited by two parallel strands of activity. In WP2, catalytically competent precious metals with intrinsically high activity will be tailored to boost the oxidation of olefins to ketones, the oxidation of water (towards efficient water splitting), and the oxidation of alkanes and arenes. WP3 is directed towards the development of sustainable catalysts based on Earth-abundant transition metals, which is promoted by the design of N,N- and N,O-bidentate (and multidentate) PYA and PYE ligands. Based on preliminary evidence, application of these complexes will be focused on copper-catalyzed C-H bond activation and on nickel-catalyzed CO2 reduction.In reaching its goals, this project will disclose new synthetic tools for organic chemistry (bond activation, olefins as protecting groups for carbonyl compounds) and will contribute to address some of the most pressing challenges towards a more sustainable society (artificial photosynthesis, CO2 transformation, better utilization of limited fossil fuel feedstocks, reduction of CO2 emission). On a fundamental level, it will promote a new class of N-donor ligands and demonstrate the importance of innovative ligand design for the improvement of the catalytic competence of transition metals and for discovering new synthetic processes.
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