Chemistry Seminar with Dr. Mike Walter from the University of North Caroline at 4:00pm
Abstract: Thiazolo[5,4-d]thiazoles (TTzs) are attractive materials for a variety of photochemical and electrochemical applications due to their simple syntheses, strong fluorescence, and high chemical stability. The unique fused, bicyclic TTz molecular structure enables multifunctional properties, high-performance fluorescence sensing, anolyte materials for redox-flow batteries, and as efficient photocatalysts. Dipyridinium, extended-viologen TTz derivatives exhibit high fluorescent quantum yields (> 90%) and reversible electrochromic properties. Simple TTz chromogenic hydrogel devices display electrochromism, electrofluorochromism, and photochromism and exhibit excellent reversibility and stable fluorescence cycling. We have also shown the ability of alkylated dipyridinium TTzs to drive the formal addition of potassium organotrifluoroborates (alkyl-BF3K) to imines with good efficiencies (isolated yields ~ 80-90%) and turnover numbers (TON, 400-700), using surprisingly low mol% (0.05-0.1) photocatalyst. Newly designed, asymmetrically substituted, push-pull TTz materials show strong solvatofluorochromism and are being evaluated as voltage-sensitive dyes for cell membrane potential sensing. Asymmetric TTzs can be used as a cell membrane VSD and have shown good cell membrane localization, insignificant cytotoxicity, and photostabilities that are 4 times higher than comparable dyes. Presented is the recent work covering these high-performance applications and current studies of TTz chromophores for efficient for solid-state fluorescence sensing, photoinduced electron transfer, photochromism, and related solar applications.
About Dr. Walter: Michael Walter earned a B.S. degree in chemistry from the University of Dayton in 2001 and as an undergraduate worked on conductive polymer syntheses at the Air Force Research Laboratory at Wright Patterson Air Force Base. He completed an M.S. degree in 2004 and Ph.D. degree in 2008 at Portland State University and joined Caltech as a postdoc in 2008. He was an NSF-ACCF postdoctoral fellow (2009-2011) studying the electrical characteristics of inorganic semiconductors in contact with conductive polymers. He joined the chemistry faculty as an assistant professor at UNC Charlotte in the fall of 2011. His research program includes the study of molecular semiconductors for solar energy conversion, porphyrin macrocycles for optoelectronic applications, and thiazolothiazole molecular photocatalysts. He is also a strong advocate for STEM outreach education and has developed several materials science related, hands-on education kits for high school science teachers and students.