Synthesis and characterization of diacylgermanes: persistent derivatives with superior photoreactivity

Abstract

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...

The Road to Bisacyldigermanes: A New Compound Class Suitable as Visible Light Photoinitiators

“…Moreover, especially for medical applications an absorption in the visible region of the light is highly beneficial. This can be achieved by the usage of germanium‐based photoinitiators, as their longest wavelength absorption is between 360 and 407 nm and tails well into the visible region [4–7,12,13] . However, the state‐of‐the‐art germanium‐based photoinitiator, namely Ivocerin®, shows insufficient curing with light sources above 450 nm, which is mainly based on the low absorption in this region.…”

“…This can be achieved by the usage of germanium-based photoinitiators, as their longest wavelength absorption is between 360 and 407 nm and tails well into the visible region. [4][5][6][7]12,13] However, the state-of-the-art germaniumbased photoinitiator, namely Ivocerin®, shows insufficient curing with light sources above 450 nm, which is mainly based…”

“…These requirements include among others a good storage stability, effective photobleaching, high efficiencies, low to no toxicity of the photoinitiator itself as well as the formed photoproducts, sustainability, environmental compatibility and not to forget a moderate price. [1] As a result, various photoinitiator compounds have appeared in literature in the last decades, including new acylphosphine oxides and derivatives, [2] a number of acylgermane compounds, [3][4][5][6][7] and some tin- [8] as well as silicon-based compounds. [9,10] Selected examples of the mentioned compounds are shown in Figure 1.…”

Recent advances on photobleachable visible light photoinitiators of polymerization

“…[217] Bis(4-methoxybenzoyl)diethylgermane (Ivocerin) is a benchmark photoinitiator. [218,219] However, its absorption remains limited beyond 500 nm so that new structures were investigated. [220] Recently, the development of a straightforward synthetic route enabling to access to tetraacylgermanes has been proposed by Haas and coworkers, enabling to produce photoinitiators with a red-shifted n-π* absorption compared to mono-and bisacylgermanes.…”

Organogermanium(iv) compounds in photo-induced radical reactions

“…In order to adjust the absorption wavelength, a series of multi-acyl-substituted germanes have been prepared as photoinitiators. [78][79][80][81][82][83][84][85][86][87] However, in photoinduced organic reactions, only single-acyl-group-substituted germanes have been used as substrates.…”