Synthesis, Crystal Structure And Anticancer Activity Of The Thiosemicarbazone Schiff-Bases And Their Metal Complexes

Recently sulfur-containing Schiff-bases compounds and their metal complexes are of much interest in bioinorganic chemistry and have been studied extensively, due to their biological properties, such as antibacterial, antiviral, antituberculostatic and anticancer activities. The biological activities of the sulfur-containing Schiff-bases compounds may be attributed to a chelation phenomenon with transition metal ions bonding through sulfur and nitrogen atoms. Similarly thiosemicarbazones and their metal complexes also have attracted a cresent interest in recent years due to their wide range of biological applications. In addition, it is found that metal complexes of thiosemicarbazones often display enhanced biological activities compared to the corresponding ligands. So researches on the synthesis and biological activities of the thiosemicarbazone schiff-base compounds and their metal complexes make a good sence in the finding of new drugs against bacteria and cancer.Heterocyclic thiosemicarbazones and their metal complexes have been studied extensively. In this paper, we investigated the synthesis, characterization, single-crystal structure and anticancer biological activities of three kinds of nitrogenous heterocyclic thiosemicarbazones and their metal complexes. The text has divided into three Chapter which were introduced as follows:Chapter 1 Synthesis, characterization and crystal structure of the pyridine thiosemicarbazone and their metal complexesTwo thiosemicarbazone ligands (HL1 and HL2) were synthesized by reaction of pyridine-3-carbaldehyde and pyridine-4-carbaldehyde with thiosemicarbazide, respectively. Then we obtained two metal complexes by reaction of pyridine-3-carbaldehyde thiosemicarbazone with manganese perchlorate in the presence of potassium thiocyanate and pyridine-4-carbaldehyde thiosemicarbazone with Zn(CH3 COO) 2·2H2 O, respectively.1. Mn(HL1 )2 (NCS) 2 (CH3 CH2 OH) 2·2C7 H8 N4S: triclinic, P-1, a = 8.896(2) A, b = 9.530(2) A, c = 14.520(4) A,α= 87.04(1)°,β= 88.11(1)°,γ= 69.43(1)°, V = 1150.9(5) A3, Z = 1, Dc = 1.420 Mg/m3,μ= 0.612 mm-1, R1 = 0.0574, wR2 = 0.1547.2. [Zn(HL2 )(CH3 COO) 2·H2 O]n: triclinic, P-1, a = 7.968(1) A, b = 9.531(1) A, c = 10.559(1) A,α= 94.44(1)°,β= 90.18(1)°,γ= 99.38(1)°, V = 788.7(2) A3, Z = 2, Dc = 1.607 Mg/m3,μ= 1.717 mm-1, R1 = 0.0491, wR2 = 0.1027. Chapter 2 Synthesis, characterization, crystal structure and antitumor activity of the pyrazine thiosemicarbazone and their metal complexesTwo thiosemicarbazone ligands (HL3 and HL4) were prepared by reacting 2-acetylpyrazine with thiosemicarbazide and 4-methyl-3-thiosemicarbazide, respectively. Reaction of the HL3 with Co(NO3) 2·6H2O leads to the formation of a cobalt complex. Otherwise we obtained two similarly iron complexes by treatment of HL3 or HL4, respectively, with iron(III) chloride hexahydrate.3. [Co(L3) 2 ]·2H2O: orthorhombic, Pbcn, a = 10.462(1) A, b = 22.653(1) A, c = 20.179(1) A, V = 4782.3(7) A3, Z = 8, Dc = 1.343 Mg/m3 ,μ= 0.921 mm -1, R1 = 0.0644, wR2 = 0.2164.4. [Fe(HL 3 ) 2 ]Cl 3·1.5H2 O: monoclinic, P21/n, a = 11.342(6) A, b = 12.547(6) A, c = 17.056(9) A,β= 103.55(1)°, V = 2360(2) A3, Z = 2, Dc = 1.632 Mg/m3,μ= 1.188 mm-1, R1 = 0.0955, wR2 = 0.2626.5. [Fe(L4)2]Cl: monoclinic, P2 1/n, a = 11.362(1) A, b = 13.502(1) A, c = 14.921(1) A, β= 104.45(1)°, V = 2216.6(4) A3, Z = 4, Dc = 1.522 Mg/m3 ,μ= 1.015 mm -1, R1 = 0.0466, wR2 = 0.0778.Chapter 3 Synthesis, characterization, crystal structure and antitumor activity of the 2-benzoylpyridine thiosemicarbazone and their metal complexesReaction of the 2-benzoyl pyridine with thiosemicarbazide leads to the formation of the 2-benzoylpyridine thiosemicarbazone ligand. Then let the ligand react with Zn(CH3 COO) 2·2H2 O and CoCl 2·6H2O, respectively. We have synthesized zinc(II) and cobalt(III) complexes of the 2- benzoylpyridine thiosemicarbazone6. [Zn(L5)2]·DMF: triclinic, P-1, a = 11.065(2) A, b = 12.651(2) A, c = 15.021(3) A,α= 114.14(1)°,β= 96.49(1)°,γ= 103.23(1)°, V = 1816.8(6) A3, Z = 2, Dc = 1.187 Mg/m3,μ= 0.824 mm-1, R1 = 0.0642, wR2 = 0.1710.7. [Co(L5 )2]Cl·4H2 O: monoclinic, P21/n, a = 10.227(3) A, b = 17.363(4) A, c = 17.459(4) A,β= 100.41(1)°, V = 3049.2(13) A3, Z = 4, Dc = 1.475 Mg/m3,μ= 0.834 mm-1, R1 = 0.0747, wR2 = 0.0896.The compounds were characterized by elemental analysis, IR, UV and MS spectroscopy and single crystal X-ray structural analysis. In addition, the antitumor activity has been evaluated for some compounds, in which some of them exhibited preferable biological activity.