1. Department of Analytical Chemistry, Faculty of Chemistry and Pharmacy, University of Sofia “St. Kl. Ohridski”, Sofia, Bulgaria
2. Department of Inorganic Chemistry, Faculty of Chemistry and Pharmacy, University of Sofia “St. Kl. Ohridski”, Sofia, Bulgaria
3. Department of Materials Science and Physical Chemistry and the Research Institute of Theoretical and Computational Chemistry (IQTCUB) of the University of Barcelona (UB), 08028 Barcelona C/Martí I Franquès 1, Spain
4. Department of Chemistry, Medical University of Varna, Varna, Bulgaria