| Coumarin and its derivatives occur widely in nature. Many natural and syntheticderivatives of coumarin are used in different applications in chemistry, biology, medicine andphysics, due to their luminescence properties. They are also used in laser dyes, nonlinearoptical chromophores, fluorescent whiteners, fluorescent probes and solar energy collectorsdue to their outstanding optical properties. Therefore, coumarin and its derivatives haveattracted considerable interests in recent years. Moreover, the benzimidazole rings as a typicalheterocyclic ligand can be formed with some main group, transition and rare-earth metalcomplexes, at the same time have good biological activity.In this paper, two ligands and eight transition metal complexes of those ligands weresynthesized. The ligands and metal complexes were measured by molecular conductivities,elemental analysis, IR, UV-Vis spectra and X-ray single crystal diffraction. Interactions of theligands and complexes with DNA were investigated by spectrophotometric methods andviscosity measurements. The fluorescence properties of the ligands were also investigated.Additionally, the antioxidant activity of the ligands and complexes were determined by thesuperoxide and hydroxyl radical scavenging methods in vitro. These complexes are listed asfollow:1.6-[bis(2-benzimidazolylmethyl)amine]coumarine（cbba）and its metal complexes:[Cd (cbba)2](pic)2·2DMF,(1)2.6-[bis(2-benzimidazolylmethyl)aminemethyl]coumarine (cbbp) and its metalcomplexes:[Cu(cbbp)(Br)(DMF)](pic),(2)[Zn(cbbp)(Cl)2]DMF,(3)[Mn(cbbp)(Cl)2]DMF,(4)[Zn(cbbp)(Br)2]DMF,(5)3. bis(2-benzimidazolylmethyl)amine (IDB) and its metal complexes:[Cu(IDB)2]2(pic)4·3DMF,(6)[Mn(IDB)2](pic)2,(7)[Ni(IDB)2]·2NO2,(8)In those complexes,(2)(3)(4)(5)(6) adopted five-coordinated modes, and except for complex(2)(6)the coordination geometry of the central metal atom may be best described as trigonalbipyramidal.(1)(7)(8) adopted six-coordinated modes, and the coordination geometry of thecentral metal atom may be best described as distorted octahedral. The results suggested thatligands and complexes can interaction with DNA in an intercalate mode. Meanwhile, ligandscbba which has a strong fluorescence response shows fluorescence quenching upon addingCu2+in Acetonitrile-H2O buffer (1:9, v/v). Additionally, we undertook a systematic investigation on the antioxidant potential of ligands and complexes and the results indicatedall complexes had stronger ability of antioxidation for hydroxyl radical except complex (5),(2)(4)(6)(7) also has good scavenging activity for superoxide radical. |
