Design, synthesis and use of phthalocyanines as a new class of visible-light photoinitiators for free-radical and cationic polymerizations

Phthalocyanines (Pcs) are interesting molecules offering fascinating chemistry that has received tremendous interest in the last decade. Certain features, such as high thermal, chemical, and optical stability, as well as unique electrochemical, photochemical and photophysical properties have opened a multitude of applications, ranging from photodynamic therapy in cancer treatment, chemical sensors, solar cells, nonlinear optics, and recently to photoinitiating systems for free-radical, cationic and controlled radical polymerizations. The success story of Pcs prompted us to highlight their significant role in photopolymerization and in materials science. In the present review, we first report on the structural design and synthesis of Pcs for specific applications and then focus on some innovative works that exploit the multiple activating properties of these macrocycles for the initiation of various modes of polymerizations under light exposure.