TY - JOUR
T1 - The Chemistry of Acylgermanes: Triacylgermenolates Represent Valuable Building Blocks for the Synthesis of a Variety of Germanium-Based Photoinitiators
AU - Frühwirt, Philipp
AU - Knöchl, Andreas Raphael
AU - Pillinger, Michael
AU - Müller, Stefanie
AU - Wasdin, Perry T.
AU - Fischer, Roland
AU - Radebner, Judith
AU - Torvisco Gomez, Ana
AU - Moszner, Norbert
AU - Kelterer, Anne-Marie
AU - Griesser, Thomas
AU - Gescheidt-Demner, Georg
AU - Haas, Michael
PY - 2020/10/19
Y1 - 2020/10/19
N2 - The formation of a stable triacylgermenolate 2 as a decisive intermediate was achieved by using three pathways. The first two methods involve the reaction of KOtBu or alternatively potassium with tetraacylgermane 1 yielding 2 via one electron transfer. The mechanism involves the formation of radical anions (shown by EPR). This reaction is highly efficient and selective. The third method is a classical salt metathesis reaction toward 2 in nearly quantitative yield. The formation of 2 was confirmed by NMR spectroscopy, UV-vis measurements, and X-ray crystallography. Germenolate 2 serves as a starting point for a wide variety of organo-germanium compounds. We demonstrate the potential of this intermediate by introducing new types of Ge-based photoinitiators 4b-4f. The UV-vis absorption spectra of 4b-4f show considerably increased band intensities due to the presence of eight or more chromophores. Moreover, compounds 4d-4f show absorption tailing up to 525 nm. The performance of these photoinitiators is demonstrated by spectroscopy (time-resolved EPR, laser flash photolysis (LFP), photobleaching (UV-vis)) and photopolymerization experiments (photo-DSC measurements).
AB - The formation of a stable triacylgermenolate 2 as a decisive intermediate was achieved by using three pathways. The first two methods involve the reaction of KOtBu or alternatively potassium with tetraacylgermane 1 yielding 2 via one electron transfer. The mechanism involves the formation of radical anions (shown by EPR). This reaction is highly efficient and selective. The third method is a classical salt metathesis reaction toward 2 in nearly quantitative yield. The formation of 2 was confirmed by NMR spectroscopy, UV-vis measurements, and X-ray crystallography. Germenolate 2 serves as a starting point for a wide variety of organo-germanium compounds. We demonstrate the potential of this intermediate by introducing new types of Ge-based photoinitiators 4b-4f. The UV-vis absorption spectra of 4b-4f show considerably increased band intensities due to the presence of eight or more chromophores. Moreover, compounds 4d-4f show absorption tailing up to 525 nm. The performance of these photoinitiators is demonstrated by spectroscopy (time-resolved EPR, laser flash photolysis (LFP), photobleaching (UV-vis)) and photopolymerization experiments (photo-DSC measurements).
UR - http://www.scopus.com/inward/record.url?scp=85093705483&partnerID=8YFLogxK
U2 - 10.1021/acs.inorgchem.0c02181
DO - 10.1021/acs.inorgchem.0c02181
M3 - Article
SN - 0020-1669
VL - 59
SP - 15204
EP - 15217
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 20
ER -