Water soluble ferrocenyl and polyferrocenyl compounds: synthesis and electrochemistry

The preparation and the electrochemical properties of different classes of water soluble ferrocenyl and multiferrocenyl compounds are described. Two strategies have been applied: (1) molecules with up to four redox units have been synthesized by quaternization of 2-(N,N-dimethylamino)ethylferrocene or 1,1′-bis(2-(N,N-dimethylamino)ethyl)ferrocene with different organic halides; (2) the synthesis of compounds with four and more redox moieties is based on the use of well established poly(propylene imine) dendrimers; the reductive amination of formyl ferrocene with the NH2-functions of these macromolecules leads to ferrocenyl dendrimers with a maximum of 64 metallocene units. The multi ammonium salts of these compounds exhibit solubility only in polar solvents. All prepared ferrocenes have been studied with voltammetric, amperometric and coulometric techniques.