TY - JOUR
T1 - Unprecedented Bifunctional Chemistry of Bis(acyl)phosphane Oxides in Aqueous and Alcoholic Media
AU - Schmallegger, Max
AU - Eibel, Anna
AU - Menzel, Jan P.
AU - Kelterer, Anne Marie
AU - Zalibera, Michal
AU - Barner-Kowollik, Christopher
AU - Grützmacher, Hansjörg
AU - Gescheidt, Georg
PY - 2019/7/5
Y1 - 2019/7/5
N2 - Tailor-made photoinitiators play an important role for efficient radical polymerisations in aqueous media, especially in hydrogel manufacturing. Bis(acyl)phosphane oxides (BAPOs) are among the most active initiators. Herein, we show that they display a remarkable photochemistry in aqueous and alcoholic media: Photolysis of BAPOs in the presence of water or alcohols provides a new delocalized π-radical, which does not participate in the polymerization. It either converts into a monoacylphosphane oxide acting as a secondary photoactive species or it works as a one-electron reducing agent. Upon the electron-transfer process, it again produces a dormant photoinitiator. We have established the structure and the chemistry of this π radical using steady-state and time-resolved (CIDEP) EPR together with ESI-MS, NMR spectroscopy, and DFT calculations. Our results show that bis(acyl)phosphane oxides act as bifunctional reagents when applied in aqueous and alcoholic media.
AB - Tailor-made photoinitiators play an important role for efficient radical polymerisations in aqueous media, especially in hydrogel manufacturing. Bis(acyl)phosphane oxides (BAPOs) are among the most active initiators. Herein, we show that they display a remarkable photochemistry in aqueous and alcoholic media: Photolysis of BAPOs in the presence of water or alcohols provides a new delocalized π-radical, which does not participate in the polymerization. It either converts into a monoacylphosphane oxide acting as a secondary photoactive species or it works as a one-electron reducing agent. Upon the electron-transfer process, it again produces a dormant photoinitiator. We have established the structure and the chemistry of this π radical using steady-state and time-resolved (CIDEP) EPR together with ESI-MS, NMR spectroscopy, and DFT calculations. Our results show that bis(acyl)phosphane oxides act as bifunctional reagents when applied in aqueous and alcoholic media.
KW - BAPOs
KW - density functional calculations
KW - ESI-MS
KW - NMR spectroscopy
KW - photochemistry
UR - http://www.scopus.com/inward/record.url?scp=85067360370&partnerID=8YFLogxK
U2 - 10.1002/chem.201900935
DO - 10.1002/chem.201900935
M3 - Article
C2 - 31070829
AN - SCOPUS:85067360370
SN - 0947-6539
VL - 25
SP - 8982
EP - 8986
JO - Chemistry - a European Journal
JF - Chemistry - a European Journal
IS - 38
ER -