Synthesis and characterization of new thiocarbohydrazone ligands and their MO(VI), V(IV) and NI(II) complexes

In the first part our this study; Two new chalcone-based symmetric bistiocarbohydrazones and one chalcone monothiocarbohydrazone were synthesized using 2'-hydroxychalcone and thiocarbohydrazide (TCH) starting substances. Three new asymmetric bistiocarbohydrazone ligands were synthesized from the reactions of the synthesized chalcone monothiocarbohydrazone with salicylaldehyde derivatives.A total of new six ligands were synthesized successfully. The interpreted structures of the ligands match exactly the predicted structures. In the second stage, a total of twenty-five new complexes were obtained, including solvated molybdenum(VI), mixed ligand vanadium(IV) and Ni(II) complexes, using symmetric and asymmetric bisthiocarbohydrazone ligands. The structures of the compounds synthesized for the first time were examined by analytical and spectroscopic methods. The X-ray single crystal structures of the appropriate crystals (nine unit ) were analyzed. When the spectroscopic data and crystal analysis results are evaluated, distorted octahedral structures are suggested for molybdenum(VI) and vanadium(IV) complexes. For nickel(II) complexes, a distorted squre planar geometric structures are seen. According to the literature, it is predicted that the ligand will not rearrange during complexation. Some of the complexes obtained support this predicted structure. In some complexes, the ligands are rearranged by cyclization during complexation. Crystal structure analyzes have been very guiding in proposing structures and new structures have been presented in the literature. In the third stage, the total antioxidant capacities of all ligands and complexes were examined and they were found to exhibit high antioxidant capacity compared to the standard substance Trolox. When the antioxidant capacities of all ligands and complexes were compared among themselves, the ligands and complexes showed higher activity when they contained a methoxy group than other derivatives that did not.