Synthesis, characterization and biological properties of bismuth(III) halide complexes of acetophenone benzaldehyde-N-alkly-thiosemicarbazones

In this thesis study, acetophenone-N-methylthiosemicarbazone (Hacpmtsc), acetophenone-N-ethylthiosemicarbazone (Hacpetsc), benzaldehyde-N-methylthiosemicarbazone (Hbzmtsc) and benzaldehyde-N-ethylthiosemicarbazone (Hbzetsc) ligands and 8 new compounds formed by these ligands with bismuth(III) halide (BiX3; X: Cl and Br) were synthesized. The synthesis of thiosemicarbazone derivative ligands was carried out by reaction of a suitable aldehyde and ketone with a thiosemicarbazide in 1:1 molar stoichiometric ratios with schiff base. Bismuth(III) halide compounds, were synthesized by using suitable solvents and temperatures in 1:2 and 1:3 metal:ligand molar stoichiometric ratios of acetophenone and benzaldehyde thiosemicarbazone derivative ligands and bismuth(III) chloride and bismuth(III) bromide. The chemical structures of synthesized ligand and bismuth(III) thiosemicarbazone compounds have been characterized by melting point, molar conductivity, FT-IR spectroscopy, FT-Raman spectroscopy, Thermal Gravimetry-Differential Thermal analysis, 1H and 13C-NMR spectroscopy, UV-Vis spectroscopy and X-ray diffraction analysis. Chemical formulas of synthesized compounds are {[BiCl2(µ2-Cl)(ƞ1-S-Hacpmtsc)2]2} (1), {[BiCl2(µ2-Cl)(ƞ1-S-Hacpetsc)2]2} (2), {[BiBr2(µ2-Br)(ƞ1-S-Hacpmtsc)2]2} (3), {[BiBr2(µ2-Br)(ƞ1-S-Hacpetsc)2]2} (4) {[BiCl3(ƞ1-S-Hbzmtsc)3]} (5), {[BiCl3(ƞ1-S-Hbzetsc)3]·(CH3OH)} (6), {[BiBr3(ƞ1-S-Hbzmtsc)3]} (7) and {[BiBr3(ƞ1-S-Hbzetsc)3]} (8). Compounds 1-4 have dimeric structure, while compounds 5-8 have monomeric structure. The monomeric units of the compounds in dimeric structure form the square pyramid geometry by bonding three halogen atoms and two sulfur atoms from the ligand to the bismuth atom, monomeric units with square pyramid geometry form the dimeric structure by connecting to each other with halogen bridges. Compounds 5-8 in monomeric structure have octahedral geometry with three halide atoms and three sulfur atoms from each ligand and meridional isomerism occurs in compounds as a result of the presence of three halogen atoms in a single plane of octahedral geometry. In this thesis study, the inhibitory effects of the lipoxygenase (LOX) enzyme of ligand and bismuth(III) thiosemicarbazone compounds, which were synthesized and their chemical structures were elucidated, were investigated. The results show that bismuth(III) compounds (1-8) have a stronger enzyme inhibition than free ligands and that the enzyme inhibition values of bismuth(III) compounds are compared with cisplatin (IC50: 65.9 µM) (2), (3) and (8) compounds appear to have a higher enzyme inhibition than cisplatin.