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-(NN-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. (C) 2001 Elsevier Science B.V. All rights reserved.