Long-chain hydrosulfides containing two secondary amide functions and either electron-poor or electron-rich carbon-carbon double bonds were self-assembled on gold surfaces around a flat-lying, octaanionic porphyrin. Rigid and reactive surface monolayers with 2 nm-wide, porphyrin-based gaps were thus obtained. The gold electrodes were then immersed in water, and the double bonds on the gaps' surfaces reacted with methylamine. It was added to the double bonds either by Michael addition or by bromination with hypobromite followed by methylamine substitution. Only the double bonds at the border of the gaps were accessible to methylamine dissolved in the bulk water volume and could react. The walls of the rigid membrane gaps now contained methylammonium groups at the sites of the double bonds in defined heights. A tetracationic copper(II) porphyrinate could not diffuse any more into the gap and did not quench the fluorescence of the octaanionic porphyrin on the bottom of the gap. A tetraanionic porphyrin, on the other hand, was fixated by the ring of ammonium groups. The bound porphyrin then acted as molecular cover for the gap with respect to ferricyanide transport from bulk water to the electrode. It was removed by raising the pH to a value of 12, where the methylammonium groups were neutralized to amines. Lowering the pH to 7 again and addition of more of the anionic porphyrin reclosed the gap.The porphyrin "cover" should be localized at distances of 8-10 and 20 A from the bottom porphyrin by multiple charge interactions. The 8-10 A distance is ideal for studies of photoinduced electron transfer between two porphyrin monomers of different redox potential. Furthermore it was found, that redox-active tyrosine could be trapped in the water volume above the porphyrin on gold.

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πEwiger Traum, da˚man etwas nicht macht, sondern es entsteht™** Einf¸hrungDie spontane Selbstorganisation amphiphiler Lipide f¸hrt in w‰ssriger Lˆsung zu kleinen Molek¸laggregaten wie Micellen, planaren Molek¸ldoppelschichten (Myelin-Figuren), Vesikeln oder biologischen Membranen. Solche Aggregate sind weich und flexibel und verhalten sich wie Fl¸ssig-keiten. Das gilt auch dann, wenn sich die Lipidaggregate bei hˆheren Konzentrationen zu micellaren Rˆhrchen (hexagonale oder kubische Phasen) zusammenlagern oder wenn sie auf festen Substraten verankert werden (Langmuir-Blodgett(LB)-Filme). Der fluide Charakter r¸hrt daher, dass die Lipidaggregate nur von schwachen, ungerichteten Kr‰ften (Van-der-Waals-Kr‰fte, hydrophobe Effekte) zusammengehalten werden und sich die Kopfgruppen gegenseitig absto˚en. [1] Trotzdem sind die kugel-und stabfˆrmigen Micellen und Vesikel in Wasser und die planaren Lipidmonoschichten auf Festkˆrperoberfl‰chen strukturell gut definiert. Die Wirkung dieser ultrad¸nnen Lipidmembranen beschr‰nkt sich allerdings auf die Solubilisierung organischer Molek¸le in Wasser,

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