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SUMMARY:Re-evaluating Photophysical Design Principles for Organic Photoredo
 x Catalysts Used in Organocatalyzed Atom Transfer Radical Polymerization
LOCATION:Chemistry, A101
TZID:America/Denver
DTSTART:20211001T160000
UID:2026-04-28-06-40-30@natsci.colostate.edu
DTSTAMP:20260428T064030
Description:Literature Seminar - Organocatalyzed atom transfer radical poly
 merization (O-ATRP) is a reversible deactivation radical polymerization me
 thod that employs organic photoredox catalysts (PCs) and visible light to 
 produce well-defined polymers. The use of organic PCs allows for polymeriz
 ations to occur under mild and energy-efficient conditions without use of 
 rare-earth metals. Understanding the correlation between excited-state pho
 tophysical properties and PC performance in O-ATRP is critical to designin
 g effective catalysts\, which leads to improved polymerization outcomes. I
 n this presentation\, a recent publication by the Orr-Ewing group that inv
 estigates excited-state photophysical properties of dihydrophenazine and p
 henoxazine PCs is discussed.1 This work challenges traditional hypotheses 
 that long excited-state lifetimes and charge transfer states\, which are t
 hought to promote intersystem crossing\, are critical parameters for super
 ior PC performance. This research is then placed in context relative to ot
 her recent publications in the field2\, 3 as well as unpublished work\, in
  which time-resolved spectroscopy has been used to characterize various or
 ganic PCs employed in O-ATRP.\nREFERENCES\n1) Bhattacherjee\, A.\; Sneha\,
  M.\; Lewis-Borrell\, L.\; Amoruso\, G.\; Oliver\, T. A. A.\; Tyler\, J.\;
  Clark\, I. P.\; Orr-Ewing\, A. J. Singlet and triplet contributions to th
 e excited-state activities of dihydrophenazine\, phenoxazine\, and phenoth
 iazine organocatalysts used in atom transfer radical polymerization. J. Am
 . Chem. Soc. 2021\, 143 (9)\, 3613-3627.\n2) Lattke\, Y. M.\; Corbin\, D. 
 A.\; Sartor\, S. M.\; McCarthy\, B. G.\; Miyake\, G. M.\; Damrauer\, N. H.
  Interrogation of O-ATRP activation conducted by singlet and triplet excit
 ed states of phenoxazine photocatalysts. J. Phys. Chem. A 2021\, 125 (15)\
 , 3109-3121.\n3) Sneha\, M.\; Bhattacherjee\, A.\; Lewis-Borrell\, L.\; Cl
 ark\, I. P.\; Orr-Ewing\, A. J. Structure-dependent electron transfer rate
 s for dihydrophenazine\, phenoxazine\, and phenothiazine photoredox cataly
 sts employed in atom transfer radical polymerization. J. Phys. Chem. B 202
 1\, 125 (28)\, 7840-7854. 4:00 pm
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