Synthesis And Antibacterial Activity Of Schiff Base Complexes Of 3-Amino-1-Adamantanol

Schiff base complexes have important applications in many fields due to their bacteriostasis,catalysis,magnetism and other properties.Adamantane and its derivatives have shown good pharmaceutical properties in the synthesis of specific drugs,which has attracted much attention of researchers.Three new Schiff bases?HL¹,HL² and HL³?and nine new complexes?1-9?were synthesized and characterized by various testing methods.Eight of complexes were characterized by X-ray single crystal diffraction,and their crystal structures were obtained.The X-ray powder diffraction of HL³ and 1-9 were also measured.In addition,the antibacterial activities of ligands?HL¹ and HL²?and their corresponding complexes?1-6?were studied.The details are as follows:1.Schiff base ligands HL¹,HL² and HL³ were synthesized by condensation of3-amino-1-adamantanol with 5-bromosalicylaldehyde or 3,5-dibromosalicylaldehyde or 4-methoxysalicylaldehyde,respectively.Then HL¹ reacted with CoCl₂·6H₂O,CuCl₂·2H₂O and ZnCl₂ in the presence of NaOH to obtain complexes,respectively:C₃₄H₃₈Br₂CoN₂O₄?1?,C₃₄H₃₈Br₂CuN₂O₄?2?,C₃₄H₃₈Br₂ZnN₂O₄?3?.In the presence of NaOH,HL² reacted with CoCl₂·6H₂O,CuCl₂·2H₂O and ZnCl₂ to obtain complexes:C₃₄H₃₆Br₄CoN₂O₄?4?,C₃₄H₃₆Br₄CuN₂O₄?5?,C₃₄H₃₆Br₄ZnN₂O₄?6?.HL³ reacted with CoCl₂·6H₂O,CuCl₂·2H₂O and ZnCl₂ in the presence of NaOH to obtain complexes:C₃₆H₄₄CoN₂O₆?7?,C₃₆H₄₄CuN₂O₆?8?,C₃₆H₄₄ZnN₂O₆?9?.2.The melting point,infrared spectra and ultraviolet-visible spectra of ligands and complexes were measured.And ligands and three zinc complexes were tested by¹H-NMR.In addition,the molar conductances of 1-9 were measured.Their possible structures were deduced by analyzing the above characterization results.Single crystals of the complexes except complex 8 were obtained by solvent slow evaporation method,and their crystal structures were obtained by X-ray single crystal diffraction analysis.The complexes are all distorted tetrahedral structures formed by N₂O₂ coordination mode.X-ray powder diffraction tests were carried out on HL³ and1-9.The peak positions of X-ray powder diffraction patterns of eight complexes with single crystal structure obtained by testing are in good agreement with the peak positions of the simulated powder diffraction patterns,which indicates that the structures of synthesized crystalline samples are identical with the single crystal structures obtained by testing.The peak positions of X-ray powder diffraction patterns of HL³ and 8 are almost different,indicating the new crystalline compound was obtained.3.The antibacterial activity of bromine substituted salicylaldehyde Schiff base?HL¹ and HL²?and their corresponding complexes?1-6?were studied.The results showed that they inhibited the three strains,had the strongest bacteriostasis against Staphylococcus aureus and weakest bacteriostasis against Escherichia coli.The ligands and complexes only inhibited Bacillus subtilis at 10^-1 and 10^-2 mol/L,and the bacteriostatic effect increased with the increase of concentration.The zinc complexes have stronger antibacterial activity against the three strains than the cobalt and copper complexes.