The Synthesis, Crystal Structure And Properties Investigations On Thiosemicarbazide Schiff Base Compounds

1. Seven organic ligands of thiosemicarbazide Schiff base have been synthesizedand characterized by elemental analysis, IR spectra, UV spectra, ¹H NMR spectra, andthe electrochemical properties have been studied by cyclic voltammetric approach.The seven ligands are 4-phenyl-1-(propan-2-ylidene)thiosemicarbazide(1),(E)-N-phenyl-2-(1-phenylethylidene)hydrazinecarbothioamide(2), 1-(1-(4-methoxy-phenyl)ethylidene)-4-phenylthiosemicarbazide(3), 1-(furan-2-ylmethylene)-4-phenylthiosemicarbazide(4), 1-(4-hydroxybenzylidene)-4-phenylthiosemicarbazide(5), 1-(butan-2-ylidene)-4-phenylthiosemicarbazide(6) and 1-(4-methylpentan-2-ylidene)-4-phenyl-thiosemicarbazide(7). Five single crystal structures of the ligands have beendetermined.2. Ten metal complexes were synthesized using two ligands of 4-phenyl-1-(propan-2-ylidene)thiosemicarbazide(1) and 1-(furan-2-ylmethylene)-4-phenyl-thiosemicarbazide(2). These complexes were synthesized via the reaction of theligands with halide of transition metal, such as Ni(â…¡), Cu(â…¡), Co(â…¡), Zn(â…¡), Cd(â…¡)inratio of 2: 1, and then characterized by elemental analysis and IR spectra. Thecomplexes for Ni(â…¡) and Cu (â…¡) of (2) were obtained and characterized by elemental analysis, IR spectra and DTG/TG.3. The crystal structure of complexes [C₂₄H₂₀N₆O₂S₂Ni] and [C₂₄H₂₀N₆O₂S₂Cu]have been determined. As a rind plane character was built up, the complexes showfluorescent property in different solvents. The results show that the maximum peakadsorption and the quantum yield were influenced by polarity of the solvents. Directelectrochemistry of the two complexes was performed in nonaqueous andethanol-water mixed solvents. The interaction of the complexes with yeast-RNA wasstudied by UV spectra and cyclic voltammetric approach, and the results show thatthey have some nuclease activity.4. The compound 5,5-dimethyl-4-phenyl-4,5-dihydro-1,2,4-triazole-3-thione wassynthesized using FeCl₃ as the oxidant. Its single crystal structures have beendetermined and the electrochemical properties been studied. The oxidation process ofbis(N-phenylthiourea) was studies by cyclic voltammetric approach and its oxidationmechanism was concluded.