Acta Phys. -Chim. Sin. ›› 2013, Vol. 29 ›› Issue (10): 2162-2172.doi: 10.3866/PKU.WHXB201308152


Synthesis and Characterization of a Cu(I) Complex of Dipyrido[3,2-a:2’,3’-c]-7-aza-phenazine and Its Interaction with DNA

GAO Yun-Yan1, CAO Lu1, OU Zhi-Ze1, CHEN Chen1, LI Yi2, WANG Xue-Song2   

  1. 1 Key Laboratory of Space Applied Physics and Chemistry of the Ministry of Education, School of Science, Northwestern Polytechnical University, Xi'an 710072, P. R. China;
    2 Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
  • Received:2013-06-20 Revised:2013-08-15 Published:2013-09-26
  • Contact: OU Zhi-Ze, GAO Yun-Yan;
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21073143),"Chunhui Project" fromthe Ministry of Education of China (Z2009-1-71002, Z2009-1-71006), NPU Foundation for Fundamental Research, China (JC200822, JC20100239), and NPU Foundation for Graduate Innovation, China.


A 1,10-phenanthroline dipyrido[3,2-a:2',3'-c]-7-aza-phenazine derivative (dpapz) and its Cu(I) complex [Cu(dpapz)2]PF6 are prepared and characterized by proton nuclear magnetic resonance spectroscopy (1H NMR), Fourier transform infrared spectroscopy (FTIR), and high resolution electrospray ionization mass spectrometry (HR ESI-MS). The interactions of dpapz and [Cu(dpapz)2]PF6 with calf thymus DNA (CT DNA) are studied by ultraviolet-visible spectroscopy (UV-Vis), fluorescence spectroscopy, DNA melting temperature, and cyclic voltammetry. When the ligand dpapz interacts with DNA, there is no red shift of the absorption peak and only a small hypochromic (<30%) effect on the absorption spectra. In addition, the interaction leads to a slight increase in the melting temperature of DNA (ΔTm=7.8 ℃). All the results indicate that groove binding is the primary interaction of dpapz with CT DNA. However, when [Cu(dpapz)2]PF6 interacts with DNA, there is a red shift of the absorption peak (2-3 nm), a large hypochromic effect on the absorption spectrum (>50%), and a significant increase in the melting temperature of DNA (ΔTm=11.1 ℃), indicating that [Cu(dpapz)2]PF6 electrostatically associates with DNA in a partial intercalation manner. The complexes of dpapz and [Cu(dpapz)2]PF6 with DNA are further confirmed by ethidium bromide (EB) fluorescence assays and cyclic voltammetry. The association constants for dpapz and [Cu(dpapz)2]PF6 with CT DNA are 2.88×105 and 5.32×105 mol·L-1, respectively. The yield of singlet oxygen produced by [Cu(dpapz)2]PF6 is similar to that of dpapz, while the yield of superoxide anion radical for [Cu(dpapz)2]PF6 is lower than that of dpapz. Active oxygen quencher experiments indicate that singlet oxygen, superoxide anion radicals, and hydrogen radicals all take part in the photocleavage of DNA by [Cu(dpapz)2]PF6 and dpapz. However, [Cu(dpapz)2]PF6 causes more photodamage of plasmid DNA than does dpapz, most likely because of its higher affinity for DNA.

Key words: Phenanthroline derivative, Cu(I) complex, Photocleavage of DNA, Active oxygen, Mode of DNAinteraction


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