Synthesis,characterization And Luminescent Property Studies Of Terephthalate Bridged Zn(?)-DNA-Macrocyclic Schiff-base Complexes

Utilizing DNA template effect,a series of symmetric or asymmetric DNA-macrocyclic Schiff-base complexes [Zn₂Cl₂LnenCl₂]?L¹ = D11-4M-D12-4M,L² = D11-4H-D12-4H,L³ = D11-4T-D12-4T,L⁴ = D11-4Cl-D12-4Cl,L⁵ = D11-4M-D12-4T,4M = 2,6-diformyl-4-methylphenol,4H = 2-hydroxyisophthaladehyde,4Cl = 2,6-diformyl-4-chlorophenol,4T = 4-Tert-butyl-2,6-diformylphenol,D11 = C151H197O90N58P15,D12 = C151H200O93N55P15?have been synthesized step by step.The compositions and structures have been characterized,and the fluorescence properties have also been studied.The complexes contain dinuclear metal unit,conforming by mass spectrometry and ultraviolet-visible absorption spectra.In the unit,the Zn???ions are with square-pyramidal configuration,with the axial position occupied by chloride ion.Fluorescence property studies shows that the fluorescence intensity of the symmetric [Zn₂Cl₂L¹en] complex is strongest,while that of the asymmetric schiff base complexes [Zn₂Cl₂L⁵en] is the weakest among the above complexes.By adjusting the p H value of the system,the tetra-nuclear zinc?II?-DNA-schiff base complexes {[Zn₂ClLn?en?]2?C8H4O4?}?n=1-4?were synthesized with the bridge of carboxylate group of terephthalate ligand,substituting terephthalate ligands for the Cl – ions at the axil position,which is conformed by mass spectrometry.The ultraviolet-visible absorption spectra indicate that the absorption peak range from 420 nm to 370 nm,duing to the metal-ligand charge transfer?MLCT?.Fluorescence property studies show that the four nuclear complexes emit fluorescence at about 500 nm,but the fluorescent intensity is greatly reduced compared with the dinuclear complexes.The terephthalic acid could be used as an effective fluorescence quenching agent in the system.