Tetraacylgermanes: Highly Efficient Photoinitiators for Visible-Light-Induced Free-Radical Polymerization.
In this contribution a convenient synthetic method to obtain tetraacylgermanes Ge[C(O)R]4(R=mesityl (1 a), phenyl (1 b)), a previously unknown class of highly efficient Ge-based photoinitiators, is described. Tetraacylgermanes are easily accessible via a one-pot synthetic protocol in >85 % yield, as confirmed by NMR spectroscopy, mass spectrometry, and X-ray crystallography. The efficiency of 1 a,b as photoinitiators is demonstrated in photobleaching (UV/Vis), time-resolved EPR (CIDEP), and NMR/CIDNP investigations as well as by photo-DSC studies. Remarkably, the tetraacylgermanes exceed the performance of currently known long-wavelength visible-light photoinitiators for free-radical polymerization.
Institute of Inorganic Chemistry, Technische Universität Graz, Stremayrgasse 9/IV, 8010, Graz, Austria.
Judith
J
Radebner
Institute of Physical and Theoretical Chemistry, Technische Universität Graz, Austria.
Anna
A
Eibel
Institute of Inorganic Chemistry, Technische Universität Graz, Stremayrgasse 9/IV, 8010, Graz, Austria.
Mario
M
Leypold
Institute of Applied Synthetic Chemistry and Christian Doppler Laboratory for Photopolymers in Digital and Restorative Dentistry, Technische Universität Wien, Austria.
Christian
C
Gorsche
Institute of Inorganic Chemistry, Technische Universität Graz, Stremayrgasse 9/IV, 8010, Graz, Austria.
Lukas
L
Schuh
Institute of Inorganic Chemistry, Technische Universität Graz, Stremayrgasse 9/IV, 8010, Graz, Austria.
Roland
R
Fischer
Institute of Inorganic Chemistry, Technische Universität Graz, Stremayrgasse 9/IV, 8010, Graz, Austria.
Ana
A
Torvisco
Institute of Physical and Theoretical Chemistry, Technische Universität Graz, Austria.
Dmytro
D
Neshchadin
Institute of Physical and Theoretical Chemistry, Technische Universität Graz, Austria.
Roman
R
Geier
Ivoclar Vivadent AG, Schaan, Liechtenstein.
Norbert
N
Moszner
Institute of Applied Synthetic Chemistry and Christian Doppler Laboratory for Photopolymers in Digital and Restorative Dentistry, Technische Universität Wien, Austria.
Robert
R
Liska
Institute of Physical and Theoretical Chemistry, Technische Universität Graz, Austria.
Georg
G
Gescheidt
Institute of Inorganic Chemistry, Technische Universität Graz, Stremayrgasse 9/IV, 8010, Graz, Austria.
Michael
M
Haas
Institute of Inorganic Chemistry, Technische Universität Graz, Stremayrgasse 9/IV, 8010, Graz, Austria.
Harald
0000-0001-8531-1964
H
Stueger
acylgermanes; photochemistry; photoinitiators; radical polymerization; reaction mechanisms