Our next webinar will take place via the internet on Tuesday October 19th at 11 AM EDT/ 4 PM BST. Sign up on our mailing list to receive the Zoom link!
We hope to see/hear from you all at one of our sessions or as one of the next speakers. If you are an early career scientist and would like to present your research, don't hesitate to submit an abstract today! For now, please learn more about our current speakers and their research below. We also thank the generous support from Cell Reports Physical Science, Merck, and the Royal Society of Chemistry.
Our featured speakers this week are Cecilia Hendy (graduate student, Emory University, USA), and Dr. Calum Ferguson (principal investigator, Max-Planck Institute for Polymer Research, Germany). The seminar will be guest-moderated by Dr Daniel Kurtz from Cell Reports Physical Science.
LEARN MORE ABOUT THE SPEAKERS AND THEIR TALKS BELOW
CECILIA HENDY (on Twitter @CeciliaHendy)
Biography: Cecilia was born in Cincinnati, Ohio and graduated with her B.S. in Chemistry from the College of Charleston in 2018. Her undergraduate research focus was on the structural characterization of neuropetides where she learned skills such as solid-phase peptide synthesis and characterization via 2D NMR experiments under the mentorship of Dr. Michael Giuliano. She is now a PhD candidate at Emory university entering her fourth year. Her graduate research has focused on method development and mechanistic investigations of visible- light catalyzed single-electron chemistry (Photoredox Catalysis) in the lab of Dr. Nathan Jui.
Title of Talk: Radical Chain Reduction via Carbon Dioxide Radical Anion
Abstract: Single electron reduction of organic molecules allows access to valuable radical intermediates that display unique reactivity when compared to their ionic counterparts. In this context, we have developed a novel reductive radical chain system that utilizes the reducing power of carbon dioxide radical anion (CO2•–; Ep/2 = –2.2 V vs SCE) to accomplish difficult reduction events. Through a polarity matched hydrogen atom transfer (HAT) between a thiyl radical and a formate salt, CO2•– formation is achieved under benign conditions (no metals required). Several initiation pathways feed into the chain mechanism via both photochemical and thermal means. We illustrate the ability of this approach to accomplish reductive activation of a range of substrate classes. Specifically, we have employed this strategy for the intermolecular hydroarylation of unactivated alkenes with (hetero)aryl chlorides/bromides, radical deamination of arylammonium salts, aliphatic ketyl radical formation, and sulfonamide cleavage. Additionally, we show that in the presence of electron deficient alkenes dual reactivity is observed; alkenes with a less negative potential than that of CO2•– undergo single electron transfer and alkenes with a more negative potential undergo Giese type conjugate addition to yield hydrocarboxylated products.
DR CALUM FERGUSON (on Twitter @cferguson28)
Biography: Calum Ferguson undertook an integrated Masters in Chemistry at The University of Edinburgh. He then attained his PhD from the University of Leeds, UK, in 2018. After the completion of his doctoral studies, he joined the department of Physical Chemistry of Polymers at the Max Planck Institute for Polymer Research (MPIP), working with Prof. Katharina Landfester. Early 2020, he started as a research group leader at MPIP. His research interests include controlled radical polymer synthesis, photocatalytic classical polymers, organic small molecule photocatalysts, and the formation of bio-mimicking polymers and colloids.
Title of Talk: Classical polymer photocatalysts: a new versatile material class
Abstract: Photocatalysis has the potential to become a powerful organic synthesis tool. Sunlight is a renewable abundant energy resource that can be used for the formation of high value compounds. Increasingly, the utilization of this energy source has been targeted as a cleaner more environmentally friendly alternative to thermal energy. The emergence of photocatalytic materials has facilitated this shift. Typically, either homogenous small molecule photocatalysts or bulky heterogeneous photocatalytic materials are utilised. Small molecular photocatalysts are highly efficient but are poorly recyclable and reusable. Heterogeneous photocatalysts are readily recoverable and reusable, but are significantly less effective than homogenous analogues. Moreover, current photocatalytic materials cannot easily be functionalised and have limited reagent selectivity. Recently we have reported a new class of polymer photocatalysts formed by combining small molecular photocatalysts with classical polymer chemistry. Creating photocatalytic polymers that contain the beneficial properties from both components. Small molecule photocatalysts will be modified to contain vinyl functionality, allowing copolymerisation with classical monomers, creating a photocatalytic polymer. Here, the material can be designed so that the active photocatalytic unit is fully solvated, ensuring high photocatalytic efficiency, similar to homogenous catalysts. While, the classical polymer support creates an easily recoverable material, analogous to heterogeneous photocatalysts. This synergistic combination also enables the production of photocatalytic polymers that can be designed for specialised applications. In our group we are interested in using this new hybrid material to produce selective photocatalytic materials. Here, we use the tuneable nature of photocatalytic classical polymers to produce materials that can selectively catalyse targeted reactions. Using a bioinspired strategy we design the local environment of the photocatalytic moiety, controlling hydrophobicity, molecular recognition and geometry of the photocatalytic active portion.