Synthesis and characterization of diacylgermanes: persistent derivatives with superior photoreactivity

Acylgermanes are known as highly efficient photoinitiators. In this contribution, we present the synthesis of new diacylgermanes 4a-e via a multiple silyl abstraction methodology. The method outperforms the state-of-the-art approach (Corey-Seebach reaction) towards diacylgermanes in terms of group t...

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Published in:Dalton transactions : an international journal of inorganic chemistry 2021-09, Vol.5 (34), p.11965-11974
Main Authors: Püschmann, Sabrina D, Frühwirt, Philipp, Müller, Stefanie M, Wagner, Stefan H, Torvisco, Ana, Fischer, Roland C, Kelterer, Anne-Marie, Griesser, Thomas, Gescheidt, Georg, Haas, Michael
Format: Article
Language:English
Subjects:
Absorption spectra
Chemistry
Crystallography
NMR
Nuclear magnetic resonance
Photoinitiators
Photolysis
Photopolymerization
Reagents
Storage stability
Synthesis
Toxicity
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Summary:Acylgermanes are known as highly efficient photoinitiators. In this contribution, we present the synthesis of new diacylgermanes 4a-e via a multiple silyl abstraction methodology. The method outperforms the state-of-the-art approach (Corey-Seebach reaction) towards diacylgermanes in terms of group tolerance and toxicity of reagents. Moreover, these compounds are decorated with bulky mesityl groups in order to improve their storage stability. The isolated diacylgermanes were characterized by multinuclear NMR-, UV-Vis spectroscopy and X-ray crystallography, as well as photolysis experiments (photobleaching) and photo-DSC measurements (photopolymerization behavior). Upon irradiation with an LED emitting at 385 nm, all compounds except for 4a and 4c bleach efficiently with quantum yields above 0.6. Due to their broad absorption bands, the compounds can be also bleached with blue light (470 nm), where especially 4e bleaches more efficiently than Ivocerin®. A series of novel diacylgermanes with bulky mesityl groups by the multiple silyl abstraction methodology, avoiding the Corey-Seebach reaction were synthesized.
ISSN:1477-9226
1477-9234
DOI:10.1039/d1dt02091a