Synthesis,Characterization,Co-releasing And Biological Activity Of Aromatic Schiff Base Modified Mn Carbonyl Complexes

Recent studies have shown that the carbon monoxide produced by human physiology can be used as a signaling molecule and has important applications in the treatment of cardiovascular diseases and inflammation.As a carbon monoxide carrier,transition metal carbonyl complexes have the advantages of controlled release of CO and low toxicity.On the other hand,Schiff-base compounds have practical application value in the fields of anti-virus,anti-bacterial,anti-inflammatory and anti-tumor due to their remarkable biological activity.Based on the application of transition metals as CO carriers and the biological activities of Schiff-base compounds,the following studies have been carried out in this paper:Firstly,we have synthesized seven aromatic Schiff-base compounds3-N-?pyridin-2-ylmethylene?pyridin-3-amine L1,4-N-?2'-pyridylimine?benzoic acid L2,2-??pyridin-3-ylimino?methyl?phenol L3,4-??2-hydroxybenzylidene?amino?benzoic acid L4,1,2-bis?pyridin-2-ylmethylene?hydrazine L5,bis?pyridin-2-ylmethylene?benzene-1,4-diamine L6 and 2,2'-?1,4-phenylenebis?azanylylidene??bis?methanylylidene?)diphenol L7 according to the literature.Secondly,seven new aromatic Schiff-base modified Mn carbonyl complexes Mn?CO?₃BrL1?1?,Mn?CO?₃BrL2?2?,Mn?CO?₃BrL3?3?,Mn?CO?₃BrL4?4?,?Mn?CO?₃Br?₂L5?5?,?Mn?CO?₃Br?₂L6?6?and?Mn?CO?₃Br?₂L7?7?were obtained by solvent refluxing or solvothermal reaction using L1^L7 as ligands to react with transition metal Mn carbonyl compound MnBr?CO?₅.Four new complexes[Mn?CO?₂?PPh₃?₂L1]ClO₄?8?,[Mn?CO?₂?PPh₃?₂L2]Cl O₄?9?,[?Mn?CO?₃?₂?PPh₃?₂L5]?C lO₄?₂?10?and[?Mn?CO?₃?₂?PPh₃?₂L6]?ClO₄?₂?11?were formed by substituting AgClO₄-PPh₃ for Br in the complexes 1,2,5 and 6,respectively.The structures of the new complexes were characterized by elemental analysis,IR,¹H-NMR and X-ray single crystal diffraction analysis.The results of CO-releasing test show that the 11new complexes have good CO-releasing properties under the irradiation of 365 nm UV light,which can be used as potential UV-controlled carbon monoxide CO-releasing molecules.In addition,this kind of complex can also release CO through the substitution of mercapto group.Finally,the cytotoxicity and intracellular diffusion of complexes 1,2,5,and 6were studied using MTT assay and laser confocal microscopy.The results show that complexes 1,2 and 6 are less toxic to normal hepatocytes and can emit fluorescence,which could be used for intracellular fluorescence labeling of CO release molecules.Complex 5 is more toxic to hepatoma cells and can be used as an anticancer agent.Laser confocal microscopy imaging results show that the complexes are mainly distributed in the cytoplasm of cells.