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Conjugated Porous Polymers for Visible Light Photocatalysis

Speaker: Dr. Kai Zhang, Max Planck Institute for Polymer Research, Germany
When: 14:00, October 19, 2017
Where: Room 410, Building B, School of Chemistry

Inspired by nature’s ability to convert solar energy into energy carrier molecules via photocatalytic processes, chemists and material scientists have developed a vast number of photocatalysts in order to mimic the nature process. A vast number of molecular inorganic, transition metal-based complexes or organic dye compounds that absorb significantly in the visible spectrum were intensely studied to harvest solar energy and catalyze organic photochemical reactions. Nevertheless, there are still some intrinsic drawbacks associated with these homogeneous systems, for instance, high cost, toxicity of these rare metals, as well as limited availability in nature, and their additionally required post-reaction purification step for catalyst removal. It is therefore of great desire to develop stable, reusable and transition metal-free photocatalysts for organic synthesis.   In this talk, conjugated porous polymers, which combine photoactive π-electron backbone and highly porous properties, will be presented as a new class of non-metallic, efficient and stable platform for heterogeneous visible light-promoted chemical transformations. A general structural design principle will be presented. A number of important properties of the novel materials, in particular, porosity, morphology, energetic band position or additional functional groups and their influence on the catalytic efficiency will be discussed. Compared to homogeneous catalysts, the porous polymer-based heterogeneous catalysts enjoy the advantage that they can be easily recycled by simple filtration due to their insoluble nature. Examples of photoredox reactions as molecular oxygen activation reaction [1], C-C or C-N bond formation [2], C-H activation reaction [3] and direct bromination reaction on aromatic compounds [4] are chosen as model photoredox reactions to demonstrate the photocatalytic efficiency of the novel materials.   [1] S. Ghasimi, S. Prescher, Z. J. Wang, K. Landfester, J. Yuan, K. A. I. Zhang, Angew. Chem. Int. Ed. 2015, 54, 14549.   [2] Z. J. Wang, S. Ghasimi, K. Landfester, K. A. I. Zhang, Adv. Mater. 2015, 27, 6265–6270.   [3] L. Wang, W. Huang, R. Li, D. Gehrig, P. W. Blom, K. Landfester, K. A. Zhang, Angew. Chem. Int. Ed. 2016, 55, 9783-9787. [4] R. Li, Z. J. Wang, L. Wang, B. C. Ma, S. Ghasimi, H. Lu, K. Landfester, K. A. I. Zhang, ACS Catalysis 2016, 6, 1113-1121.

Speaker biography:

Kai Zhang did his undergraduate and master study from 2002 to 2007 in the Department of Chemistry at the University of Cologne, Germany. He completed his PhD in 2010 under the supervision of Professor Bernd Tieke in Cologne, and also in the group of Professor Peter Skabara at the University of Strathclyde, Glasgow, UK, within a joint PhD program, working on novel conjugated polymers. From 2011 to 2013, he worked as a postdoctoral researcher with Professor Markus Antonietti at the Max Planck Institute of Colloids and Interfaces in Potsdam, Germany.   In the beginning of 2013 he joined the Max Planck Institute for Polymer Research (MPI-P) as a research group leader. Currently, Kai is leading the laboratory of photocatalysis at MPI-P. His research activity is mainly focused on photoactive porous polymer materials for catalytic studies.