Photo-CIDNP evidence for charge-transfer interaction between synthetic water-soluble porphyrins and guanine

Synthesis of amphipathic porphyrins and their photoinduced electron transfer reactions at the lipid bilayer-water interface

A one flask synthesis of cis-substituted amphipathic porphyrins is reported. These porphyrins were used to study electrostatic effects on photoinduced electron transfer across the lipid bilayer-water interface. A neutral porphyrin undergoes only dynamic interfacial electron transfer reactions irrespective of charge of the acceptor, although ionic strength effects indicate a negative charge on the porphyrin donor species. A dianionic porphyrin forms an interfacial static complex with a dicationic electron acceptor, methyl viologen, at low ionic strength. The electron transfer rate within the complex is slow, 10(5) approximately 10(6) s-1, which is attributed to a near orthogonal orientation between the donor and the acceptor pi orbitals.