TY - JOUR
T1 - Maximizing Photon-to-Electron Conversion for Atom Efficient Photoredox Catalysis
AU - Draper, Felicity
AU - DiLuzio, Stephen
AU - Sayre, Hannah J.
AU - Pham, Le Nhan
AU - Coote, Michelle L.
AU - Doeven, Egan H.
AU - Francis, Paul S.
AU - Connell, Timothy U.
PY - 2024/10/2
Y1 - 2024/10/2
N2 - Photoredox catalysis is a powerful tool to access challenging and diverse syntheses. Absorption of visible light forms the excited state catalyst (*PC) but photons may be wasted if one of several unproductive pathways occur. Facile dissociation of the charge-separated encounter complex [PC•-:D•+], also known as (solvent) cage escape, is required for productive chemistry and directly governs availability of the critical PC•- intermediate. Competitive charge recombination, either inside or outside the solvent cage, may limit the overall efficiency of a photochemical reaction or internal quantum yield (defined as the moles of product formed per mole of photons absorbed by PC). Measuring the cage escape efficiency (ϕCE) typically requires time-resolved spectroscopy; however, we demonstrate how to estimate ϕCE using steady-state techniques that measure the efficiency of PC•- formation (ϕPC). Our results show that choice of electron donor critically impacts ϕPC, which directly correlates to improved synthetic and internal quantum yields. Furthermore, we demonstrate how modest structural differences between photocatalysts may afford a sizable effect on reactivity due to changes in ϕPC, and by extension ϕCE. Optimizing experimental conditions for cage escape provides photochemical reactions with improved atom economy and energy input, paving the way for sustainable design of photocatalytic systems.
AB - Photoredox catalysis is a powerful tool to access challenging and diverse syntheses. Absorption of visible light forms the excited state catalyst (*PC) but photons may be wasted if one of several unproductive pathways occur. Facile dissociation of the charge-separated encounter complex [PC•-:D•+], also known as (solvent) cage escape, is required for productive chemistry and directly governs availability of the critical PC•- intermediate. Competitive charge recombination, either inside or outside the solvent cage, may limit the overall efficiency of a photochemical reaction or internal quantum yield (defined as the moles of product formed per mole of photons absorbed by PC). Measuring the cage escape efficiency (ϕCE) typically requires time-resolved spectroscopy; however, we demonstrate how to estimate ϕCE using steady-state techniques that measure the efficiency of PC•- formation (ϕPC). Our results show that choice of electron donor critically impacts ϕPC, which directly correlates to improved synthetic and internal quantum yields. Furthermore, we demonstrate how modest structural differences between photocatalysts may afford a sizable effect on reactivity due to changes in ϕPC, and by extension ϕCE. Optimizing experimental conditions for cage escape provides photochemical reactions with improved atom economy and energy input, paving the way for sustainable design of photocatalytic systems.
KW - Photoredox catalysis
KW - photon to electron conversion
KW - Excited states
KW - photons
KW - photocatalysts
KW - quantum yields
UR - http://www.scopus.com/inward/record.url?scp=85204707159&partnerID=8YFLogxK
UR - http://purl.org/au-research/grants/ARC/DE210101168
UR - http://purl.org/au-research/grants/ARC/DP210100025
UR - http://purl.org/au-research/grants/ARC/DP220100300
U2 - 10.1021/jacs.4c07396
DO - 10.1021/jacs.4c07396
M3 - Article
C2 - 39302225
AN - SCOPUS:85204707159
SN - 0002-7863
VL - 146
SP - 26830
EP - 26843
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 39
ER -