Photopolymerization is an unavoidable polymerization technique used in plethora applications. If benzophenone or thioxanthone have been popular UV photoinitiators, these two structures are unsuitable for performing polymerization experiments in the visible region due to insufficient absorptions. With regards to thioxanthone and in order to redshift its absorption towards the visible range, numerous core-extended thioxanthones have been proposed, enabling to shift their absorptions at longer wavelengths and thus to elaborate visible light photoinitiators. In this field, thioxanthonation of dyes has been extensively studied but the major drawback of this approach was the access to polyaromatic structures exhibiting a low solubility in monomers, adversely affecting the monomer conversion. To address this issue, innovative strategies were envisioned to extend the π-conjugation of thioxanthone while providing an excellent solubility to photoinitiators both in common organic solvents and in monomers. In this review, the different strategies developed to access to these core-extended thioxanthones are detailed and the photopolymerization performance discussed.

光聚合是一种在众多应用中不可避免的聚合技术。如果二苯甲酮或噻吨酮一直是流行的紫外光引发剂，那么这两种结构由于吸收不足而不适合在可见光区域进行聚合实验。对于噻吨酮，为了将其吸收红移至可见光范围，已经提出了许多核心延伸的噻吨酮，使其能够在更长的波长下移动其吸收，从而制成可见光光引发剂。在这一领域，染料的噻吨酮化已被广泛研究，但该方法的主要缺点是获得在单体中表现出低溶解度的聚芳族结构，从而对单体转化率产生不利影响。为了解决这个问题，人们设想了创新策略来延长噻吨酮的π-共轭，同时为光引发剂在普通有机溶剂和单体中提供优异的溶解度。在这篇综述中，详细介绍了为获得这些核心延伸的噻吨酮而开发的不同策略，并讨论了光聚合性能。