Studies On The Synthesis, Crystal Structure, Biological Activity Of First-Row Transition Metal Complexes With 3, 5-Dichlorosalicylaldehyde Acylhydrazone

Acylhydrazone compounds are made by nucleophilic addition and dehydration reaction of acylhydrazines and aldehydes or ketones. It belongs to a species of particular Schiff base which isn′t hydrolyzed easily since there is a p-Ï€conjugation in acylhydrazone group. Acylhydrazone compounds and its complexes has become the topic of intensive research in recent years due to their bio-activities, such as antibacterial activities and some pharmacological activities, and their excellent properties of chemical analysis, catalytic-activities and non-linear optics. In this contribution, different kinds of acylhydrazone and complexes were synthesized by 3, 5-Dichlorosalicylaldehyde and acylhydrazine, and they were cultivated to be single crystal, and they were applied in biology. Its specific contents and conclusions are as follows:The synthesis of 3, 5-Dichlorosalicylaldehyde thiosemicarbazone(H₂L1) was carried out, and prepare complexes with general method. The crystal structure of the complex [Co(L1)₂]·DMF(â… ), [Cu(L1)(DMF)]·DMF(â…¡), Ni(L1)(Phen)(CH3OH)(â…¢), Zn(L1)(Phen)(â…£) was obtained. Three verification was taken and shows that they belong to monoclinic. The space group ofâ… is P21/c, the central ion is six coordinated. The space group ofâ…¡,â…¢,â…£are P21/n, the central Cu(â…¡) is four coordinated, the central Ni(â…¡) is six coordinated, the central Zn(â…¡) is five coordinated. Two similar chains which like DNA double helix formed by two non-classical hydrogen bonds Cl-H and S-H ofâ… andâ…¡. The copper ion ofâ…¡link the adjacent molecular by Jahn-Teller effect form a chain.The synthesis of N'-(3, 5-dichloro-2-hydroxybenzylidene)-2-pyridinecarbohydrazide (H₂L2) was carried out, and prepare two new"grid"complexes with Ni(NO3)₂ and MnCl2. The crystal structure of the complex [Ni4(L2)₄(DMF)₄]·2H₂O(â…¤), Mn4(L2)₄(DMF)₄(â…¥) was obtained. Three verification was taken and shows that they belong to triclinic, the space group are PÄ«, central ions is six coordinated. With analysis of bonds and bond angles of the complexes, we have found the ligand anion L2 and Ni(â…¡) are the best match betweenâ…¤andâ…¥.The synthesis of N'-(3, N'-(3, 5-dichloro-2-hydroxybenzylidene)-4-pyridinecarbohydrazide (H₂L3) was carried out, and prepare complexes with CoCl2. The crystal structure of the complex [Co(H₂L3)₂(Phen)]Cl2·CH3OH(â…¦) was obtained. Three verification was taken and shows that they belong to orthorhombic, the space group is Pna21, central ion is six coordinated. The acylhydrazone group ofâ…¦with an unusual"zero dentate"coordinated type. In the view the interactions of intermolecular ofâ… ^â…¦, halogen bonds is an important factor to stabilize the crystal cell packing structures. Refer to《Technical Standard For disinfection》(Ministry of Health of People's Republic of China, 2002), an antibacterial test forâ…¡,â…£, the derivatives of halogeno-salicylaldehyde thiosemicarbazone and their some complex have been made. The results show that the antibacterial potency is changed with the kind of halgen of benzene. The number of halogen of benzene is more, the antibacterial potency is stronger. The metal ion is an important factor to influence the disinfectant effect of complexes. Of all these compounds, only Cu(â…¡) complexes have sensitive inhibitory activity to Candida albicans(ATCC 10231).Comprehensively study on properties of thermostability, UV, fluorescence, CV ofâ…¤,â…¥and H₂L2. Their TG/DTG curves show that in the range of definite temperatureâ…¤lost 4 DMF molecules at one time, moreover,â…¥lost 2 DMF molecules. These results were decided by the chemical environment of DMF molecules in complexes especially the coordinated bonds with central ions. At room temperature their UV spectra show thatâ…¤has stronger absorption peaks at 267nm, 334nm, 426nm,â…¥has stronger absorption peaks at 266nm, 329nm, 421nm, compared with the absorption peak at 338nm of H₂L2, the ligand coordinate with metal ions lead to violet shift. While the molar absorption coefficient ofâ…¥at 329nm is almost 2 times thanâ…¤at 334nm. It account for the reducing capacity of central Mn ion is stronger than Ni ion. H₂L2 has a fluorescence peak at 540 nm, compared withâ…¤andâ…¥, the spectra of complexes occur red shift and quench at the same position. The quench capacity ofâ…¤andâ…¥is equal. The CV spectra ofâ…¤,â…¥show that there is no activity in the electrode reaction.A mimic SOD activity test for H₂L2, H₂L3, complexâ…¤^â…¦have been made. Onlyâ…¥is an ideal mimic SOD enzyme, its IC50 value is 0.53μM. There is no change in the UV spectra of solution of PBS/DMF(v/v=90:10) from 15min²4h ofâ…¥. This reveal thatâ…¥is stable in the solution of PBS/DMF(v/v=90:10) and suitable for a mimic SOD. Compared with its DMF solution, the pattern of UV spectrum ofâ…¥in the solution of PBS/DMF(v/v=90:10)are similar, only at 399nm(ε=5240), 298nm(ε=5460) occur red shift, this can be seen the DMF molecules ofâ…¥replaced by water. Further research find that the van der Waals space-filling drawing of complexâ…¥exist a similar hydrophobic"basket"and weak coordinated solvent channel which found in crude SOD enzyme, these may be the crucial reason ofⅥ′s mimic SOD activity.