Christian Messerschmidt

Dimerization of metallated pigments as primary step in the construction of membrane gaps on gold, polymeric wires and isolable micelles

β-Octasubstituted porphyrins form face-to-face dimers in solution, which are stabilized by π-π′ interactions in case of π-radical formation. Polymerization of viologen substituted zinc porphyrins leads depending on stereochemistry to micelles or wire pairs. Anionic porphyrins were also adsorbed to gold electrodes or colloids and entrapped in membrane gaps. Heterodimerization of these porphyrins adsorbed to solid phase surfaces and entrapped within a 2 nm membrane gap was detectable by fluorescence quenching. Ruthenium complexes with two bipyridyl and one dioctadecyl dipyridyl methylene malonate ligand form head-to-head dimers in aqueous solution. The octadecyl substituents of the dimer constituents point to opposite directions and large multilayer micelles are formed upon aggregatetion in water. They survive drying. Dimerization processes are discussed as common basis for the formation of four uncommon supramolecular assemblies.

Non-covalent chiral fibres in aqueous gels and their functionalization

The fully reversible synthesis of noncovalent assemblies which are held together by directed bonds is called synkinesis. Micellar fibres with a distinct stereochemistry and gels are formed by amphiphiles forming strong hydrogen bonds between chiral head groups. The 3D-crystallization of such molecular assemblies, without dominating repulsive hydration forces, is prevented by the curvature of the fibres. Curvature might perhaps be directly connected with chirality. Addition of enantiomers often leads to an irreversible destruction of gels. Recent developments relating to ‘hydrophobic water’ in Ångström-wide membrane gaps are also shortly discussed.