Far-Red Light-Induced Reversible Addition-Fragmentation Chain Transfer Polymerization Using a Man-Made Bacteriochlorin.

To overcome the challenge of photoregulated living radical polymerization in long-wavelength radiation, a photoinduced electron transfer reversible addition-fragmentation chain transfer (PET-RAFT) polymerization in far-red wavelength (λ = 740 nm) is reported by using a man-made bacteriochlorin as a photocatalyst. A reduced tetraphenylporphyrin (RTPP) having a natural bacteriochlorin macrocycle ring with two reduced pyrrole rings was synthesized with strong absorption in the far-red light region (700-765 nm) and applied for the PET-RAFT polymerization as a photoredox catalyst, which offered excellent control over molecular weight and polydispersities and oxygen tolerance for the polymerization of (methyl) acrylates monomers, and exhibited attractive features of "living" radical polymerization. Benefiting from high penetration of far-red light, the polymerization was also well-controlled when the reaction vessel was covered by translucent animal tissue barriers, for example, skin.