Pillar[6]arene: Light Cleaves Macrocycle to Linear Oligomer Biradical to Initiate Photopolymerization

A novel kind of photoinitiator based on the macrocyclic molecule pillar[6]arene (P6OC2H5) is reported. Under light irradiation, P6OC2H5 was cleaved to a linear oligomer biradical, which could efficiently initiate free-radical photopolymerization. Owing to the absence of small molecular fragment generation, the macrocyclic photoinitiator exhibited a much lower migration rate and cytotoxicity than commercial photoinitiators. This is the first time that a macrocyclic molecule has been developed as a photoinitiator based on the macrocycle fracture mechanism.