Redox processes of dithiolated tetraazamacrocyclic complexes of Ni(II) and Cu(II) in solution and immobilized on gold electrodes

Urszula E. Wawrzyniak 1Bohdan Korybut-Daszkiewicz 2Sławomir Domagała 1Krzysztof Woźniak 1Renata Bilewicz 1

1. Warsaw University, Department of Chemistry, Pasteura 1, Warsaw 02-093, Poland
2. Polish Academy of Science, Institute of Organic Chemistry, Kasprzaka 44/52, Warsaw 01-224, Poland

Abstract

Tetraazamacrocyclic complexes of Cu(II) and Ni(II) designed as building blocks of catenanes and rotaxanes were synthesized and structurally characterized in the solid state using X-ray diffraction techniques. In our present studies, we modify these compounds with organothiol chains to attach them to the surface of the electrode using the self-assembly method. The electrochemical properties of these compounds are studied in the solution and, in the case of Ni-dithiol derivative ( Fig. 1), immobilized on the electrode surface. Voltammetric studies of the new cooper complexes dissolved in acetonitrile solutions indicate that macrocyclic architectures based on 2 and 3 tetraazamacrocylic complex units bound by means of two or three (-S-S-) bonds remain stable in nonaqueous solutions and may be useful as building blocks for more complex structures in solution. For the bis and tris macrocyclic compounds studied, the exchange of 1e takes place almost independently at each of the copper centers. The electrochemistry of the Ni macrocycle complex shown below is examined and the electron transfer kinetics are evaluated. The electrochemical experiments reveal reversible one-electron redox processes of the metal center at the +2/+3 oxidation state. The Ni(II)-dithiol derivative can be anchored to the surface by one or two thiol groups. We demonstrate that the thread – like structure is predominant allowing formation of a pseudorotaxane with a p-electron rich compound dissolved in the solution.

scheme.jpg

Fig 1. Macrocyclic complexes immobilized on the gold electrode surface

 

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Presentation: Poster at SMCBS'2007 International Workshop, by Urszula E. Wawrzyniak
See On-line Journal of SMCBS'2007 International Workshop

Submitted: 2007-08-31 19:15
Revised:   2009-06-07 00:44