Studies on the Synthesis, Crystal Structure, Biological Activity of First-Row Transition Metal Complexes with 3, 5-Dichlorosalicylaldehyde Acylhydrazone
|School||Guilin University of Technology|
|Keywords||3，5-Dichlorosalicylaldehyde acylhydrazone transition metal crystal structure biological activity|
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-πconjugation 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（Ⅰ）, [Cu（L1）（DMF）]·DMF（Ⅱ）, Ni（L1）（Phen）（CH3OH）（Ⅲ）, Zn（L1）（Phen）（Ⅳ） was obtained. Three verification was taken and shows that they belong to monoclinic. The space group ofⅠis P21/c, the central ion is six coordinated. The space group ofⅡ,Ⅲ,Ⅳare P21/n, the central Cu（Ⅱ） is four coordinated, the central Ni（Ⅱ） is six coordinated, the central Zn（Ⅱ） is five coordinated. Two similar chains which like DNA double helix formed by two non-classical hydrogen bonds Cl-H and S-H ofⅠandⅡ. The copper ion ofⅡlink 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（Ⅴ）, Mn4（L2）4（DMF）4（Ⅵ） was obtained. Three verification was taken and shows that they belong to triclinic, the space group are Pī, central ions is six coordinated. With analysis of bonds and bond angles of the complexes, we have found the ligand anion L2 and Ni（Ⅱ） are the best match betweenⅤandⅥ.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（Ⅶ） 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 ofⅦwith an unusual“zero dentate”coordinated type. In the view the interactions of intermolecular ofⅠⅦ, 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 forⅡ,Ⅳ, 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（Ⅱ） complexes have sensitive inhibitory activity to Candida albicans（ATCC 10231）.Comprehensively study on properties of thermostability, UV, fluorescence, CV ofⅤ,Ⅵand H2L2. Their TG/DTG curves show that in the range of definite temperatureⅤlost 4 DMF molecules at one time, moreover,Ⅵlost 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 thatⅤhas stronger absorption peaks at 267nm, 334nm, 426nm,Ⅵhas 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 ofⅥat 329nm is almost 2 times thanⅤat 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 withⅤandⅥ, the spectra of complexes occur red shift and quench at the same position. The quench capacity ofⅤandⅥis equal. The CV spectra ofⅤ,Ⅵshow that there is no activity in the electrode reaction.A mimic SOD activity test for H2L2, H2L3, complexⅤⅦhave been made. OnlyⅥis 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 ofⅥ. This reveal thatⅥis 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 ofⅥin 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 ofⅥreplaced by water. Further research find that the van der Waals space-filling drawing of complexⅥexist 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.