Energy Transfer and Electron Transfer of Poly(ethylene glycol)-Linked Fluorinated Porphyrin Derivatives in Lipid Bilayers

Abstract

Poly(ethylene glycol) [PEG]-linked porphyrin derivatives separated by spacer methylene groups (Cn), PEG−Cn−MPFPP (M = H2, Mn; n = 0, 5, 11), PEG−C11−MTTP (M = H2, Mn), and PEG−C0−MPFPPBr8 (M = H2, Mn) (Scheme 1) were synthesized. The porphyrin portion of the poly(ethylene glycol) [PEG]-linked fluorinated porphyrin derivative has been anchored onto a lipid bilayer. PEG-linked fluorinated porphyrins easily associated with phospholipid bilayers and are chemically stable against oxidants such as H2O2. An efficient energy transfer from phospholipid-linked zinc porphyrin, PE−C0−ZnPFPP (Scheme 1), to externally added PEG−Cn−H2PFPP (n = 0, 5, 11) in the lipid bilayer was observed, depending on the length of Cn and the porphyrin structure. Ground state transmembrane electron transfer catalyzed by PEG−Cn−MnPFPP (n = 0, 5, 11) and PEG−C11−MnTTP revealed that the porphyrin causes a significant accelerated electron transfer especially when n = 11. Comparison of PEG−C11−MnPFPP- and PEG−C11−MnTTP-catalyzed electron transfer is made. The electron transfer rate was controlled not only by the separated spacer methylene groups between the porphyrin and PEG moieties but also by the structures of porphyrins.