In this work, three dyes based on fused carbazole–coumarin–ketone structures were designed and synthesized. These dyes were named CCK–Me, CCK–Ph, and CCK–Tol in accordance with their different substituents. Their excellent absorption properties can match the wavelength band of visible light-emitting diodes (LEDs) (i.e., 405–450 nm). Density functional theory calculations, steady-state photolysis, and electron spinning resonance spin trapping experiments were performed to explain the photophysical and photochemical mechanisms of the dyes. These dyes are available as one- or two-component type II photoinitiators (PIs). Both kinds can efficiently initiate the polymerization of acrylate monomers via two different mechanisms under 405–450 nm LED irradiation. Notably, CCK–Tol exhibited excellent photobleaching ability when initiated alone, making it ideal for deep curing. The polymeric samples were up to 57 mm thick. Remarkably, the photolysis product of CCK–Tol showed satisfactorily low cytotoxicity. The above excellent properties showed the great potential application of the dyes in various photocuring materials, especially dental materials and thick three-dimensional structures.

中文翻译：

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熔融咔唑-香豆素-酮染料：自由基光聚合中的高性能和可光漂白光引发剂，用于可见 LED 光照射下的深度光固化

在这项工作中，设计并合成了三种基于稠合咔唑-香豆素-酮结构的染料。这些染料根据其不同的取代基被命名为 CCK-Me、CCK-Ph 和 CCK-Tol。它们优异的吸收特性可以匹配可见光发光二极管（LED）的波段（即405-450 nm）。进行了密度泛函理论计算、稳态光解和电子自旋共振自旋俘获实验来解释染料的光物理和光化学机制。这些染料可用作单组分或双组分 II 型光引发剂 (PI)。两种都可以通过以下途径有效地引发丙烯酸酯单体的聚合405-450 nm LED 照射下的两种不同机制。值得注意的是，CCK-Tol 在单独引发时表现出出色的光漂白能力，使其成为深度固化的理想选择。聚合物样品厚达 57 毫米。值得注意的是，CCK-Tol 的光解产物表现出令人满意的低细胞毒性。上述优异性能表明该染料在各种光固化材料，尤其是牙科材料和厚三维结构中具有巨大的应用潜力。