1. Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., bld. 11, 1113 Sofia, Bulgaria
2. Department Chemistry and Biochemistry, Faculty of Pharmacy, Medical University—Pleven, Kl. Ohridski Str., 1, 5800 Pleven, Bulgaria
3. Department Biotechnology, Faculty of Chemical and Systems Engineering, University of Chemical Technology and Metallurgy, Kl. Ohridski Blvd, 8, 1756 Sofia, Bulgaria