Synthesis,Characterization And Properties Of Six Novel Heterocyclic Schiff Bases Of Benzil Dihydrazone

Schiff base is a class of organic compounds containing the core group imine or methylimine（-RC=N-）.Usually,Schiff base is synthesized by the condensation of an amine and an active carbonyl group.The formula of Schiff base is R₁R₂C=NR₃.Various Schiff bases with different functional characteristics can be obtained bychanging the structures of amine or aldehyde.At the same time,the Schiff base ligand can coordinate with various metal ions leading to the formation of various complexes.In recent years,a large number of novel Schiff bases have been synthesized and studied for the treatment of cancer,HIV,Alzheimer,malaria and parasitic diseases.Due to the simplicity in syntheses,coordination versatility of the-C=N-N=C-fragments and changeable structures,Schiff-bases derived from benzil dihydrazone（BDH）have become a kind of excellent ligands in the design and synthesis of new materials.Also known as a class of bio-active compounds,benzil dihydrazone-based Schiff bases deserve to be further studied in their synthesis,structure and properties.In terms of synthesis and structure,BDH was used as the common start material to react with 1-formylnaphtyalene,2-formylfuran,3,4-dimethoxy benzaldehyde,2-acetylpyrazine,4-acetylbiphenyl,and phenylethanone,respectively,in the solvent of anhydrous methanol,acetonitrile or 1,2-propanediol.As a result,six Schiff bases,i.e.benzil dihydrazone-N,N’-bis（1-formylnaphtyalene）（BDHFN）,benzil dihydrazone-N N’-bis（2-formylfuran）（BDHFF）,benzil dihydrazone-N N’-bis（3,4-dimethoxy benzaldehyde）（BDHMB）,benzil dihydrazone-N,N-bis（2-Acetylpyrazine）（BDHAP）,benzildihydrazone-N,N-bis（4-Acetylbiphenyl）（BDHAB）,andbenzil dihydrazone-N-bis（phenyl methyl ketone）（BDHPMK）,were obtained.The as-synthesized compounds were characterized by single crystal X-ray diffraction,elemental analysis,¹HNMR and UV-Vis.Chemical Abstract searching proves that they are new compounds that have not been reported before.After the confirmation of their structures,the fluorescence emission spectra have been performed.The results proved that all of them have good fluorescence properties.Most of the fluorescence peaks are between 310 and 380 nm,hoping to be used as fluorescence materials.At last,the in vitro inhibitory activity of six Schiff bases have been performed by the MTT method against human lung cancer A549 cell lines.It was found that only BDHMB has moderate inhibitory activity(IC₅₀=73.0μmol/L).While the IC₅₀values of other Schiff bases are greater than 100μmol/L.The inhibitory activities against other cancer cell lines and various bacteria are on-going.