1. Biomolecular and Organic Electronics, Department of Physics, Chemistry and Biology, Linköping University, Linköping SE-581 83, Sweden
2. Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Göteborg SE-412 96, Sweden
3. Department of Chemistry, Addis Ababa University, P.O. Box 33658, Addis Ababa, Ethiopia
4. Department of Chemistry, Wollo University, P.O. Box 1145, Dessie, Ethiopia