Synthesis of “Porphyrin-Linker-Thiol” Molecules with Diverse Linkers for Studies of Molecular-Based Information Storage

Abstract

The attachment of redox-active molecules such as porphyrins to an electroactive surface provides an attractive approach for electrically addressable molecular-based information storage. Porphyrins are readily attached to a gold surface via thiol linkers. The rate of electron transfer between the electroactive surface and the porphyrin is one of the key factors that dictates suitability for molecular-based memory storage. This rate depends on the type and length of the linker connecting the thiol unit to the porphyrin. We have developed different routes for the preparation of thiol-derivatized porphyrins with eight different linkers. Two sets of linkers explore the effects of linker length and conjugation, with one set comprising phenylethyne units and one set comprising alkyl units. One electron-deficient linker has four fluorine atoms attached directly to a thiophenyl unit. To facilitate the synthesis of the porphyrins, convenient routes have been developed to a wide range of aldehydes possessing a protected S-acetylthio group. An efficient synthesis of 1-(S-acetylthio)-4-iodobenzene also has been developed. A set of porphyrins, each bearing one S-acetyl-derivatized linker at one meso position and mesityl moieties at the three remaining meso positions, has been synthesized. Altogether seven new aldehydes, eight free base porphyrins and eight zinc porphyrins have been prepared. The zinc porphyrins bearing the different linkers all form self-assembled monolayers (SAMs) on gold via in situ cleavage of the S-acetyl protecting group. The SAM of each porphyrin is electrochemically robust and exhibits two reversible oxidation waves.

Synthesis of Stably Water-Soluble Gold Nanoparticles Protected by Porphyrin-Thiol Derivative

“…Tetradentate TMP ligand with four thioacetyl groups may contribute the strong protection to the Au nanoparticles. Once the TMP ligands protect the Au surfaces, thioester groups spontaneously dissociate to form thiolates and generate self-assembled monolayer on bare Au surface [10]. Consequently, the highly stably water-soluble TMP-Au nanoparticles were obtained.…”

“…DMSO oxidation of 2 at room temperature provided aldehyde 3 as pale yellow oil in moderate yield, 44%. TMP ligand was obtained using Lindsay's method [10] as a purple solid in 41% yield. All compounds were identified by 1 H-NMR and EI-or ESI-MS.…”

Synthesis, Optical and Photovoltaic Properties of Porphyrin Dyes

“…Subsequent iodination and metallation gave mono-and diiodoporphyrins (28). The porphyrinyl iodides 6 and 7 were coupled with ethynyltriarylamine by Sonogashira cross-coupling reaction to give the conjugated porphyrin-triarylamine hybrids 8 and 9 (29)(30)(31)(32). Porphyrin esters 8 and 9 were saponified by NaOH, followed by acidification to generate their corresponding carboxylic acids 2 and 3.…”

Gold(0) Porphyrins on Gold Nanoparticles

“…The SC 1 P ligand was designed with methylene groups inserted between the benzene rings and the acetylthio groups in order to increase the distance between the porphyrin ring and the Au surface. The SC n P (n = 0, 1) ligands were synthesized from the corresponding aldehyde and pyrrole using Lindseys method [10] in 15 % and 40 % yields, respectively.[11] Since the acetylthio groups easily dissociate to form S-Au bonds on bare Au surfaces in a slightly alkaline condition, [12] these groups are considered an excellent thiol source to protect the Au surface. The SC n Pprotected Au (SC n P-Au) nanoparticles were prepared by ligand-exchange reactions from citrate-protected Au (CAAu) nanoparticles.…”