Synthesis of thiol-derivatized porphyrin dimers and trimers for studies ofarchitectural effects on multibit information storage

We present the rational design and synthesis of multiporphyrin arrays conta ining thiol-derivatized linkers for the purpose of multibit molecular infor mation storage. Porphyrin dimers and trimers were synthesized by the Pd-med iated coupling of iodo-substituted and ethynyl-substituted porphyrin buildi ng blocks in 5-51% yields. Each porphyrin dimer bears one S-acetylthio grou p, The architecture of the trimers incorporates a trans-substituted porphyr in (central) bearing two S-acetylthio groups and two diphenylethyne-linked porphyrins (wings) in a trans geometry. The central porphyrin and the wing porphyrins bear distinct substituents and central metals, thereby affording different oxidation potentials. The S-acetylthio groups provide a means fo r attachment of the arrays to an electroactive surface. The dimers are desi gned for vertical orientation on an electroactive surface-while the trimers are designed for horizontal orientation of the central porphyrin. Altogeth er seven different arrays were synthesized. Each array forms a self-assembl ed monolayer (SAM) on gold via in situ cleavage of the S-acetyl protecting group. The SAM of each array is electrochemically robust and exhibits multi ple, reversible oxidation waves. In general, however, the trimeric arrays a ppear to form more highly ordered monolayers that exhibit sharper, better-d efined redox features.