1. Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
2. Institute of Mineralogy and Crystallography, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. bl. 107, 1113 Sofia, Bulgaria
3. Bruker BioSpin GmbH, Silberstreifen, 76287 Rheinstetten, Germany
4. Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. bl. 9, 1113 Sofia, Bulgaria