Acylstannanes: Cleavable and Highly Reactive Photoinitiators for Radical Photopolymerization at Wavelengths above 500 nm with Excellent Photobleaching Behavior

Within this work, a novel acylstannane‐based photoinitiator (PI) is presented. Tetrakis(2,4,6‐trimethylbenzoyl)stannane (1) displays outstanding properties compared to state‐of‐the‐art acylgermane‐based initiators. Most importantly, the initiator shows absorption up to 550 nm, which allows higher penetration depths, especially in highly filled photopolymers. Besides that, 1 shows extremely high photoinitiating activity towards (meth)acrylic double bonds, as well as very fast photobleaching. Furthermore, unlike many organotin compounds, 1 shows surprisingly low cytotoxicity. A new cure: A novel acylstannane‐based visible‐light photoinitiator, tetrakis(2,4,6‐trimethylbenzoyl)stannane (1), shows absorption at wavelengths up to 550 nm, which results in higher penetration depths, especially in highly filled photopolymers. Photoinitiator 1 also shows extremely high photoinitiating activity towards (meth)acrylic double bonds, very fast photobleaching and surprisingly low cytotoxicity.