We will have a seminar this Friday (15.10) from Angel Andres Castro Ruiz, PhD student at the Faculty of Physical Sciences, University of Iceland. The seminar is a PhD midterm evaluation, see more information and abstract below.
Hope to see all of you there!
When and where: Friday 15.10, 12:30-13:10, Room 157 VR-II
Title: Bio-inspired cobalt complexes for high value-added oxygenated materials
Abstract: Societal needs to transform waste carbon dioxide (CO2) into biodegradable polymers, both to reduce industrial greenhouse gas emissions and to convert an environmental threat into biocompatible products for biomedical applications is a promising area. Metalloenzymes are very efficient and selective catalysts in the conversion of small molecules in nature, they are ideal models upon which to base synthetic mimics able to efficiently convert CO2 into high value-added materials. These biological catalysts often feature earth-abundant metals such as cobalt surrounded by protein scaffolds, while specific scaffold features responsible for favorable influences are often not known.
Inspired by unsurpassed stereochemical control and catalytic efficiency of metalloenzymes, cobalt complexes with environmentally safe amino acids were chosen for this purpose. In this work a new selective synthetic route for cobalt complexes type [CoII(aa)2(en)] (aa: amino acids; en: bipy, dtbbpy = 4,4’-di-tert-butylbipyridine) was designed resulting in three compound libraries. The synthesis developed is versatile since it enables systematic change of the amino acids and the substituents on the bipy ligand. The system proved active in reactions requiring substrate activation by a Lewis acidic site such as in ROP of lactide to produce PLA. To better understand the structure-reactivity relationship of this new system in CO2 activation, screening runs of a mechanistically related CO2/epoxides coupling reactions were performed. Preliminary kinetic profiling using real-time in situ IR spectroscopy revealed that this system displays outstanding efficiency and chemoselectivity towards cyclic carbonate formation. The observed (initial) TOFs exceed 1125 h-1 which is among the highest reported for mononuclear cobalt-based catalysts in this area of CO2 conversion. The current catalytic system presents a useful, readily available, cost-efficient and above all highly active alternative for the synthesis of cyclic carbonates.
Pétur Orri Heiðarsson
Department of Biochemistry
Askja- The Natural Sciences Building
University of Iceland
Sturlugata 7, 102 Reykjavík
Office +354 5254276