* Corresponding authors

^a Chemistry Department, Faculty of Chemistry and Chemical Engineering, Babes-Bolyai University, 11 Arany J. Street, Cluj-Napoca, Romania
E-mail: diudea@chem.ubbcluj.ro
Fax: +40 264 590818

^b Molecular and Biomolecular Physics Department, National Institute for R&D of Isotopic and Molecular Technologies, 65-103 Donath Street, Cluj-Napoca, Romania