engleski

NMR and DFT studies of hydrogen bonding in thiosemicarbazones

Thiosemicarbazones and their metal complexes belong to important class of compounds that posses anti-infective, anti-inflammatory and anti-cancer biological activity. Thiosemicarbazones can act as tridentate ligands coordinated through the deprotonated phenolic O, imino N and thiocarbazone S, or as doubly negatively charged tridentate ligands by loosing a proton from the tautomeric mercapto group. Thiosemicarbazones ligands can form intramolecular hydrogen bonds in the solid state as demonstrated by X-ray diffraction. These interactions can influence the structural properties and play significant role in molecular recognition processes. This is important with respect to their biological activity. In order to fully characterize hydrogen bonding in 4-phenyl-salicylaldehide-thiosemicarbazon (1) in solution we have employed NMR and DFT methods. The structure of (1) was deduced by using standard one and two-dimensional NMR techniques. Solvents of different donor and acceptor abilities were used to study changes in intra- and inter-molecular hydrogen bonding network. NMR measurements were performed at various temperatures and concentrations. 13C chemical shifts in different solvents were compared to those calculated by using DFT (GIAO1) method and 6-311++G** basis set.

NMR; DFT; thiosemicarbazones

nije evidentirano