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

拟议的项目追求两个研究目标。第一个涉及新的双酰基磷烷氧化物（BAPOs）RPO（COR`）2的合成，这将伴随着磷结合取代基R的系统修饰。根据量子化学计算，取代基R对酰基膦的光化学性质起着重要的作用。这些新合成的化合物将作为光引发剂应用于木材、皮革和金属（钛）的新型表面功能化，其中丙烯酸酯的聚合反应是通过将光活性磷化合物固定在相应的表面上，在可见光下引发的。由此产生的混合材料（被有机聚合物层包覆的天然基底）以其改进的性能而闻名，因此激发了该项目第二部分（特别是科学创新部分）对更高效的光引发剂的探索。后者专注于合成新的可LED激活的水溶性钛和硅化合物。在钛的情况下，将设想具有通式Ti（acac）2（COR）2（acac =乙酰丙酮化物）的酰基钛酸酯，因为如果与BAPO（P-C键）相比，它们更容易裂解Ti-C键。到目前为止，这类双酰基钛酸酯在文献中是未知的，尽管它们的合成和开发已经奠定了40年前的一个有前途的基础。除了钛化合物，一些硅基光引发剂作为光固化材料的添加剂将被合成和表征。在光活性四（酰基）硅烷中用具有吸电子取代基的芳基取代异亚丙基部分应导致更有效地吸收由LED聚合灯发射的光。为了能够选择性地固定酰基硅烷，将合成和研究通式RSi（COR ′）3的新化合物类。这两种方法的结合（引入吸电子基团和用适合于表面固定的取代基R官能化RSi（COR`）3）将对基础研究做出有价值的贡献，并为用于表面细化的全新类型的高效光引发剂铺平道路。

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.