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UID:20250510T225552EDT-51196u0ufe@132.216.98.100
DTSTAMP:20250511T025552Z
DESCRIPTION:Abstract:\n\nMelanins are ubiquitous natural pigments that colo
 r human skin\, overripe bananas\, cephalopod ink\, and iridescent peacock 
 feathers to name just a few examples. While sunscreening is the best-known
  function of melanin in skin\, melanins also bind metal ions and scavenge 
 radicals. Property emergence in melanins is of great interest not only for
  understanding their biological function but also for creating bioinspired
 \, multi-functional materials that exploit melanin’s intrinsic electronic 
 and ionic conductivity\, redox activity\, ability to stabilize free radica
 ls\, and broadband optical absorption. These properties are attractive for
  applications in bioelectronics\, catalysis\, energy conversion and storag
 e. Remarkably\, the atomistic structures present in melanins are obscure d
 espite more than a century of effort\, impeding understanding of their str
 ucture-function relationships. To gain insight into the chromophores of me
 lanin\, femtosecond transient absorption experiments have been carried out
  on synthetic melanin polymers. Transient spectral holes centered about th
 e laser excitation wavelength are detected at room temperature\, providing
  evidence of absorbers with a broad distribution of transition energies. T
 he observed bleach recovery dynamics provide valuable insights into coupli
 ngs among melanin’s chromophores. By combining femtosecond time-resolved i
 nfrared (TRIR) spectroscopy with the ability to select chromophore subense
 mbles with a tunable UV-vis excitation pulse\, a vibrational fingerprintin
 g technique is demonstrated that correlates electronic and vibrational pro
 perties of melanin’s chromophores. These top-down studies are augmented by
  a bottom-up research program to construct a melanin mimic from structural
 ly well-defined subunits. This work has led to intriguing stabilized quino
 nes that reproduce several of melanin’s hallmark properties.\n\n \n\nBio:
 \n\nBern Kohler is Professor and Ohio Eminent Scholar in the Department of
  Chemistry and Biochemistry at The Ohio State University. He and his co-wo
 rkers study biopolymer photophysics and photochemistry using ultrafast las
 er spectroscopy. Further research projects include the study of fundamenta
 l\, light-driven events in organic and inorganic nanomaterials of interest
  for solar energy conversion and photocatalysis. Prof. Kohler received a B
 .S. degree in chemistry from Stanford University (1985)\, a Ph.D. in physi
 cal chemistry from MIT (1990)\, and he completed postdoctoral research at 
 the Swiss Federal Institute of Technology in Zurich\, Switzerland and at t
 he University of California\, San Diego. Prof. Kohler is a fellow of the A
 AAS and the winner of the 2017 Inter-American Photochemical Society Award 
 in Photochemistry. He is a Past-President of the Telluride Science Researc
 h Center and has served on the Executive Committee of the ACS Physical Div
 ision.\n
DTSTART:20230117T180000Z
DTEND:20230117T193000Z
LOCATION:Room 10\, Maass Chemistry Building\, CA\, QC\, Montreal\, H3A 0B8\
 , 801 rue Sherbrooke Ouest
SUMMARY:Chemical Society Seminar: -Bern Kohler- The Melanin Elephant: A Spe
 ctroscopist’s View of Nature’s Mysterious Pigment
URL:/chemistry/channels/event/chemical-society-seminar
 -bern-kohler-melanin-elephant-spectroscopists-view-natures-mysterious-3431
 45
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