Synthesis and Invesitigation of New, LED-Activatable Photoinitiators for Surface Refinement

• Applicant: Dr. Anna Widera
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: from 2021 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 458684978

The proposed project pursues two research aims. The first one deals with the synthesis of new bisacylphosphane oxides (BAPOs) RPO(COR`)2 that will be accompanied by a systematic modification of the phosphorus bound substituent R. According to quantum chemical calculations, the substituent R plays an important role for the photochemical properties of the acylphosphanes. The newly synthesized compounds will subsequently be investigated with regard to their application as photoinitiators in novel surface functionalizations of the widely used materials wood, leather and metal (titanium).Herein, polymerization of acrylate should be triggered with visible light by immobilizing photoactive phosphorus compounds on the respective surface. The resulting hybrid materials (natural substrates coated by an organic polymer layer) are known for improved properties, thus motivating the exploration of further efficient photoinitiators in the second, particularly scientifically innovative part of the project.The latter focuses on the synthesis of new, LED-activatable and water soluble titanium and silicon compounds. In the case of titanium, acyltitanates with the general formula Ti(acac)2(COR)2 (acac = acetylacetonate) will be envisioned due to their easier cleavable Ti-C bond if compared to BAPOs (P-C bond). Up to the present, such bisacyltitanates are not known in literature even though a promising foundation for their synthesis and exploration has already been laid 40 years ago.In addition to the titanium compounds, a number of silicon-based photoinitiators as additives in light curing materials will be synthesized and characterized. The substitution of mesityl moieties by aryl groups with electron withdrawing substituents in a photoactive tetra(acyl)silane should result in a more efficient absorption of the light emitted by a LED polymerization lamp. In order to enable a selective immobilisation of the acylsilanes, a new compound class of the general formula RSi(COR`)3 will be synthesized and investigated. The combination of these two approaches (the introduction of electron withdrawing groups and the functionalization of RSi(COR`)3 with a substituent R being suitable for surface fixation) will both valuably contribute to the fundamental research and pave the way for an entirely new type of efficient photoinitiators for surface refinement.

• DFG Programme: WBP Fellowship
• International Connection: Switzerland
• Host: Professor Dr. Hansjörg Grützmacher