Abstract:
A series of dyes based on the phenazine skeleton were synthesized. They differed in the number of conjugated double bonds, the arrangement of aromatic rings (linear and/or angular system), as well as the number and position of nitrogen atoms in the molecule. These compounds were investigated as potential singlet oxygen sensitizers and visible light absorbers in dye photoinitiating systems for radical polymerization. The quantum yield of the singlet oxygen formation was determined by the comparative method based on the 1H NMR spectra recorded for the tested dyes in the presence of 2,3-diphenyl-p-dioxene before and after irradiation. The quantum yield of the triplet state formation was estimated based on the transient absorption spectra recorded using the nanosecond flash photolysis technique. The effectiveness of the dye photoinitiating system was characterized by the initial rate of trimethylolpropane triacrylate (TMPTA) polymerization. In the investigated photoinitiating systems, the sensitizer was an electron acceptor, whereas the co-initiator was an electron donor. The effectiveness of TMPTA photoinitiated polymerization clearly depended on the arrangement of aromatic rings and the number of nitrogen atoms in the modified phenazine structure as well as the quantum yield of the triplet state formation of the photosensitizer in the visible light region.
摘要:
合成了一系列基于吩嗪骨架的染料。它们的共轭双键数量不同,芳环的排列(线性和/或角度系统),以及分子中氮原子的数量和位置。研究了这些化合物作为自由基聚合的染料光引发体系中潜在的单线态氧敏化剂和可见光吸收剂。单线态氧形成的量子产率是通过比较方法确定的,该方法基于在辐照之前和之后在2,3-二苯基-对二恶烯存在下对测试染料记录的1HNMR光谱。基于使用纳秒闪光光解技术记录的瞬态吸收光谱来估计三重态形成的量子产率。染料光引发体系的有效性通过三羟甲基丙烷三丙烯酸酯(TMPTA)聚合的初始速率来表征。在所研究的光引发系统中,敏化剂是电子受体,而共引发剂是电子供体。TMPTA光引发聚合的有效性显然取决于芳环的排列和修饰的吩嗪结构中的氮原子数以及可见光区域中光敏剂三重态形成的量子产率。