Recent advances on visible light photoinitiators of polymerization based on Indane-1,3-dione and related derivatives

Photoinitiators that can operate under visible light and low light intensity are actively researched as this last generation of photoinitiators can address different issues raised by the traditional UV photoinitiators. Notably, the safety concern related to the use of UV light, the high energy consumption resulting from the use of UV irradiation setups, the low light penetration of UV light within the photocurable resins are three major concerns that visible light photoinitiators successfully address. Besides, the photoinitiating ability and the polymerization kinetic should remain high in order these new generations of photoinitiators to be capable to replace the traditional UV photoinitiators. Among the different scaffolds examined for the design of efficient visible light photoinitiators, indane-1,3-dione has been identified as a promising scaffold for the design of various structures. By the presence of the activated methylene group standing between the two ketone groups, this electron acceptor is an ideal candidate for the design of push-pull dyes by one of the simplest reactions, namely the Knoevenagel reaction. This group is also a good electron acceptor as the two ketone groups can be advantageously used in the electronic delocalization by mesomerism. If this electron acceptor has been extensively studied for the design of push-pull dyes, its scope of application was not only limited to the design of push-pull dyes and products issued from cyclization reactions, the design of compounds with extended aromaticities, improvement of the electron-withdrawing ability by substitution of the ketone groups by appropriate groups were examined as possible chemical modifications enabling to improve the photoinitiating ability of photoinitiators based on indane-1,3-dione and its related derivatives. In this review, an overview of the different visible light photoinitiators based on indane-1,3-dione and derivatives is provided. To evidence the performance of the different photoinitiators, comparisons with reference compounds will be provided.

Automated summary

Visible light photoinitiators that can operate under low light intensity are actively researched to address safety concerns and high energy consumption issues associated with traditional UV photoinitiators. Among these, indane-1,3-dione has been identified as a promising scaffold for design of various structures in this last generation of photoinitiators. Comparisons with reference compounds are provided to evaluate the performance of these photoinitiators.