Thursday, 02 March, 2017
UTK Host: Dr. David Baker, Professor of Chemistry
Speaker: Dr. Seth Marder
Regents Professor, Georgia Power Chair of Energy Efficiency
Professor of Chemistry and Materials Science & Engineering
Georgia Institute of Technology
Title: “Synthesis of Molecules and Dopants for Organic Electronic Applications”
Abstract: In the first section, we will discuss doping of carbon-based materials which are emerging as important components for a wide range of electronic applications. p- and n-Doping of charge-transporting materials with oxidants or reductants respectively can significantly improve the behavior of organic electronic devices. Metallo-organic and organic dopants that are sufficiently reducing to n-dope many electron-transport materials of interest, especially for photovoltaic and light-emitting diode applications, via simple one-electron transfer are typically air-sensitive. Approaches in which air-stable precursors react to form dopants during, or subsequent to, device fabrication have the potential to greatly simplify device fabrication. Here we will discuss the development of transition-metal complexes for doping of materials deposited from solution, including strongly reducing, yet air-stable, n-dopants.
In the second section, we will focus on the synthesis of organic moieties with high electron affinities (EA) that may act as intra- and intermolecular acceptors in p-conjugated materials. Incorporation of strong p-acceptors into either small molecule or polymer materials can be problematic since many high-EA precursors are resistant to electrophilic halogenation and lithiated derivatives typically used to form Stille and Suzuki reagents are often unstable. Direct C-H bond functionalization on sp2 carbon centers has become a useful tool for the synthesis of p-conjugated small molecules and polymers. Direct C-H arylation can be particularly useful in the synthesis of materials with high EA, where it may be used to circumvent some of the synthetic difficulties associated with strongly electron-accepting intermediates and with conventional cross-coupling partners. To explore the scope of direct C-H arylation of high EA materials, we have synthesized several heterocycles based on widely used 2,1,3-benzothiadiazole (BT), benzotriazole (BTz), and quinoxaline (Qx) acceptors with pendant electron withdrawing substituents to increase EA relative to the parent acceptors. Palladium-catalyzed direct heteroarylation of 5,6-dicyano[2,1,3]benzothiadiazole (DCBT), 5,6-dicyano[1,2,3]benzotriazole (DCBTz), and 6,7-dicyanoquinoxaline (DCQx), was accomplished with high yields (>80%) of di-coupled products in most cases. Finally, we will discuss a simple method for iodinating high EA materials which are otherwise difficult to halogenate.
Biography: Seth Marder is currently the Georgia Power Chair of Energy Efficiency and Regents’ Professor in the School of Chemistry and Biochemistry and a Professor of Materials Science and Engineering (courtesy) at the Georgia Institute of Technology (Georgia Tech). Dr. Marder received his B.A. degree in Chemistry from MIT in 1978 and his Ph.D. from the University of Wisconsin-Madison in 1985. He is a Fellow of the American Association for the Advancement of Science (2003), the Optical Society of America (2004), SPIE (2006), the Royal Society of Chemistry (2007), the American Physical Society (2009) the Materials Research Society (2014). He received a 2011 American Chemical Society A.C. Cope Scholar Award, and the 2015 MRS Mid-Career Award.
for the 2017 Spring Chemistry Schedule.
Web Cast: This seminar is not web cast.