| Abstract
| - One approach toward storage of multiple bits of information at the molecular level requires theconstruction of molecular architectures comprised of multiple redox-active units. Four newferrocene−porphyrins have been synthesized to investigate questions concerning (1) the scope ofredox-active molecules that can be employed in molecular information-storage schemes and (2)writing/reading rates as well as retention of charge in redox-active units located at different sitesin a molecular architecture. Three of the ferrocene−porphyrins have linkers of different lengthsbetween the ferrocene and porphyrin. The fourth ferrocene−porphyrin has two ferrocenes positionedat the lateral sites on the porphyrin. The latter architecture is designed to provide a shorter distancebetween the electroactive surface and the ferrocene while maintaining an upright orientation ofthe porphyrin. Each ferrocene−porphyrin affords three cationic oxidation states (ferrocenemonocation, porphyrin monocation, porphyrin dication) in addition to the neutral state, therebyaffording the capability of storing two bits of information. Each ferrocene−porphyrin bears anS-acetyl or S-(N-ethyl)carbamoyl-protected thiol moiety, thereby avoiding handling of free thiols.Each ferrocene−porphyrin forms a self-assembled monolayer (SAM) on gold via in situ cleavage ofthe thiol protecting group. The SAM of each array is electrochemically robust and exhibits threewell-resolved, reversible oxidation waves.
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