From Biomimetic Ion Carriers to Helical Structures

Biomimetic chemistry aims at reproducing the functions of natural compounds with the simplest possible synthetic molecules. Our strategy in this endeavor involved: (i) first reproduction of elementary processes such as molecular recognition, mass- transport, electron-transport, and signaling, and (ii) subsequently integration of several of these properties into single molecules. We approached the problems of molecular recognition and mass- transport by concentrating on the design and synthesis of all-artificial iron(III)-carriers that mimic the properties of microbial siderophores (iron(III) carriers): (i) the capability to effectively bind iron(III), (ii) to interact with specific membrane receptors as their iron(III)-complexes, and (iii) to transport iron(III) into the cells’ interior. Conjugation of the synthetic carriers with fluorescent markers enabled us to couple molecular recognition with signaling and to thereby provide diagnostic tools for the identification of specific microorganisms. The knowledge gained in the course of this work was then applied to the synthesis of (i) triple-stranded binders that form helical, dinuclear complexes, and of (ii) helical structures where four elementary process are integrated into a single molecule to provide molecular »redox-switches«