A bipodal-tethered porphyrin for attachment to silicon surfaces in studies of molecular information storage.

An approach for molecular information storage entails use of redox-active molecules attached to an electroactive surface. Understanding the structural features that give rise to robust molecular monolayers with high charge density is an essential objective. Toward this goal, a zinc-porphyrin bearing an all-carbon bipodal tether, 5-(1,6-heptadien-4-yl)-15-phenyl-10,20-di-p-tolylporphinatozinc(II), has been synthesized by the reaction of a dipyrromethane and a dipyrromethane-1,9-dicarbinol.

Comparison of electron-transfer rates for metal- versus ring-centered redox processes of porphyrins in monolayers on Au(111).

The standard electron-transfer rate constants ( k ( 0 )) are measured for redox processes of Fe versus Zn porphyrins in monolayers on Au(111); the former undergoes a metal-centered redox process (conversion between Fe (III) and Fe (II) oxidation states) whereas the latter undergoes a ring-centered redox process (conversion between the neutral porphyrin and the pi-cation radical). Each porphyrin contains three meso-mesityl groups and a benzyl thiol for surface attachment. Under identical solvent (propylene carbonate)/electrolyte (1.

Metal-molecule interactions upon deposition of copper overlayers on reactively functionalized porphyrin monolayers on Si(100).

The interaction of evaporated Cu deposited on a series of porphyrins in monolayers covalently attached to Si(100) substrates was investigated using cyclic voltammetry and FTIR spectroscopy. Each porphyrin contains a triallyl tripod attached to the porphyrin via a p-phenylene unit. The tripod anchors the porphyrin to the Si(100) substrate via hydrosilylation of the allyl groups.

Synthesis and photophysical characterization of porphyrin, chlorin and bacteriochlorin molecules bearing tethers for surface attachment.

The ability to tailor synthetic porphyrin, chlorin and bacteriochlorin molecules holds promise for diverse studies in artificial photosynthesis. Toward this goal, the synthesis and photophysical characterization of five tetrapyrrole compounds is described. Each compound bears a surface attachment group.

Stepwise formation and characterization of covalently linked multiporphyrin-imide architectures on Si(100).

A major challenge in molecular electronics and related fields entails the fabrication of elaborate molecular architectures on electroactive surfaces to yield hybrid molecular/semiconductor systems. A method has been developed for the stepwise synthesis of oligomers of porphyrins linked covalently via imide units. A triallyl-porphyrin bearing an amino group serves as the base unit on Si(100), and the alternating use of a dianhydride (3,3',4,4'-biphenyltetracarboxylic dianhydride) and a porphyrin-diamine for reaction enables the rapid and simple buildup of oligomers composed of 2-5 porphyrins.

Investigation of stepwise covalent synthesis on a surface yielding porphyrin-based multicomponent architectures.

Porphyrins have been shown to be a viable medium for use in molecular-based information storage applications. The success of this application requires the construction of a stack of components ("electroactive surface/tether/charge-storage molecule/linker/electrolyte/top contact") that can withstand high-temperature conditions during fabrication (up to 400 degrees C) and operation (up to 140 degrees C). To identify suitable chemistry that enables in situ stepwise synthesis of covalently linked architectures on an electroactive surface, three sets of zinc porphyrins (22 altogether) have been prepared.

Diastereoselective assembling of 21-C-alkylated nickel(II) complexes of inverted porphyrin on a platinum(II) template.

Reaction of 21-C-methyl and 21-C-benzyl nickel(II) complexes of inverted meso-tetratolylporphyrin with platinum(II) dichloride or its bis(benzonitrile) complex yields a chloroplatinum(II) species containing two nickel(II) carbaporphyrinoids in a cis arrangement. One of the carbaporphyrinoids coordinates to the platinum ion with the external nitrogen while the other is bound with the external nitrogen and one ortho-carbon of the adjacent meso-aryl ring. The reaction is highly chemoselective.

Nickel(II) complexes of 21-C-alkylated inverted porphyrins: synthesis, protonation, and redox properties.

Reaction of the nickel(II) complex of an inverted porphyrin, (5,10,15,20-tetraphenyl-2-aza-21-carbaporphyrinato)nickel(II) (1), with haloalkanes in the presence of proton scavengers yields 21-C-alkylated complexes. The products are separated and characterized spectroscopically. Chirality of the formed substituted metalloporphyrins is discussed on the basis of the (1)H NMR spectra.

Alkylation of the inverted porphyrin nickel(II) complex by dihalogenalkanes: formation of monomeric and dimeric derivatives.

An efficient and simple method of modification of "inverted" porphyrin is provided by reactions of 5,10,15,20-tetraaryl-2-aza-21-carbaporphyrinatonickel(II) 2 with dihalogenalkanes under basic conditions. The substituents are bound to the internal carbon or external nitrogen of the inverted pyrrole depending on dihalogenalkane and basic catalyst. The monomeric 2- or 21-ethoxymethyl-substituted species are formed in the reaction of 2 with dihalomethanes and sodium ethoxide or ethanol in the presence of K(2)CO(3).

First example of a covalently bound dimeric inverted porphyrin.

Reaction of 5,10,15,20-tetraphenyl-2-aza-21-carbaporphyrinatonickel(II) with dihalomethanes in the presence of a proton scavenger gives a 2,21'-CH2-linked dimer of Ni(II) inverted porphyrins with the yield reaching 90% and its 2,2'-linked isomer as a minor product.