Journal of Chemical Sciences

, Volume 117, Issue 2, pp 179–186 | Cite as

Mixed-ligand copper(II) complexes of dipicolylamine and 1,10-phenanthrolines: The role of diimines in the interaction of the complexes with DNA

  • S Ramakrishnan
  • M PalaniandavarEmail author


Mixed-ligand copper(II) complexes of the type [Cu(dipica)(diimine)](ClO4)2, where dipica is di(2-picolyl)amine and diimine is 1,10-phenanthroline (phen), 5,6-dimethyl-1,10-phenanthroline (5,6-dmp), 2,9-dimethyl-1,10-phenanthroline (2,9-dmp) or dipyridoquinoxaline (dpq), have been isolated and characterized by analytical and spectral methods. The copper(II) complexes exhibit a broad band in the visible region around 675 nm and axial EPR spectra in acetonitrile glass (77 K) with g and A values of ∼2·22 and 185 × 10−4 cm−1 respectively, suggesting the presence of a square-based coordination geometry for the CuN5 chromophore involving strong axial interaction. The interaction of the complexes with CT DNA has been studied using absorption, emission and circular dichroic spectral methods and viscosity measurements. Absorption spectral titrations reveal that the intrinsic DNA binding affinities are dependent upon the nature of the diimine ligand: dpq > 5,6-dmp > phen > 2,9-dmp. This suggests the involvement of the diimine rather than the dipica ‘face’ of the complexes in DNA binding. An intercalative mode of DNA interaction, which involves the insertion of dpq and to a lesser extent the phen ring of the complexes in between the DNA base pairs, is proposed. However, interestingly, the 5,6-dmp complex is involved in hydrophobic interaction of the 5,6-dmp ring in the grooves of DNA. The large enhancement in the relative viscosity of DNA on binding to the dpq and 5,6-dmp complexes supports the proposed DNA binding modes. Further, remarkably, the 5,6-dmp complex is selective in exhibiting a positive-induced CD band on binding to DNA suggesting the transition of the B form of CT DNA to A-like conformation. The variation in relative emission intensities of DNA-bound ethidium bromide observed upon treatment with the complexes parallels the trend in DNA binding affinities.


Mixed-ligand Cu(II) complexes dipica and 1,10-phenanthrolines DNA binding studies CD spectroscopy 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Dervan P B 1986 Science 464 6232Google Scholar
  2. 2.
    Lu P, Zhu M L and Yang P 2003 J. Inorg. Biochem. 95 31CrossRefGoogle Scholar
  3. 3.
    Wu J Z, Li H, Zhang J G and Xu J H 2002 Inorg. Chem. Commun. 5 71CrossRefGoogle Scholar
  4. 4.
    Hemmert C, Pitie M, Renz M, Gornitzka H, Soulet S and Meunier B 2001 J. Biol. Inorg. Chem. 6 14CrossRefGoogle Scholar
  5. 5.
    Navarro M, Cisneros-Fajardo E J, Sierralta A, Fernadez-Mastre M, Silva P, Arrieche D and Marchan E 2003 J. Biol. Inorg. Chem. 8 401Google Scholar
  6. 6.
    Liu J, Mei W J, Lin L J, Zheng K C, Chao H, Yun F C and Ji L N 2004 Inorg. Chim. Acta 357 285CrossRefGoogle Scholar
  7. 7.
    Chao H, Mei W J, Huang Q W and Ji L N 2002 J. Inorg. Biochem. 92 165CrossRefGoogle Scholar
  8. 8.
    Wu J Z and Yuan L 2004 J. Inorg. Biochem. 98 41CrossRefGoogle Scholar
  9. 9.
    Arounagiri S and Maiya B G 1996 Inorg. Chem. 35 4267CrossRefGoogle Scholar
  10. 10.
    Pitie M, Horn V D J, Brion D, Burrows C J and Meunier B 2000 Bioconjugate Chem. 11 892CrossRefGoogle Scholar
  11. 11.
    Chand D K, Schneider H J, Bencini A, Bianchi A, Georgi C, Ciattini S and Valtancoli B 2000 Chem. Eur. J. 6 4001CrossRefGoogle Scholar
  12. 12.
    Lamour E, Routier S, Bernier J L, Catteau J P, Bailly C and Vezin H J 1999 J. Am. Chem. Soc. 121 862CrossRefGoogle Scholar
  13. 13.
    Povirk L F 1991 Mutat. Res. 257 127CrossRefGoogle Scholar
  14. 14.
    Sigman D S, Graham D R, Aurora V D and Stern A M 1979 J. Biol. Chem. 254 12269Google Scholar
  15. 15.
    Spassky A and Sigman D S 1985 Biochemistry 24 8050CrossRefGoogle Scholar
  16. 16.
    Mahadevan S and Palaniandavar M 1998 Inorg. Chem. 37 693CrossRefGoogle Scholar
  17. 17.
    Ranford J D, Sadler P J and Tocher D A 1993 J. Chem. Soc., Dalton Trans. 3393Google Scholar
  18. 18.
    Chikira M, Tomizava Y, Fukita D, Sugizaki T, Sugawara N, Yamazaki T, Sasano A, Shindo S, Palaniandavar M and Anthroline W E 2002 J. Inorg. Biochem. 89 163CrossRefGoogle Scholar
  19. 19.
    Santra B K, Reddy P A N, Neelakanta G, Mahadevan S, Nethaji M and Chakravarty A R 2002 J. Inorg. Biochem. 89 191CrossRefGoogle Scholar
  20. 20.
    Dhar S, Senapati D, Das P K, Chattopadhyay P, Nethaji M and Chakravarty A R 2003 J. Am. Chem. Soc. 125 12118CrossRefGoogle Scholar
  21. 21.
    Dhar S, Reddy P A N, Nethaji M, Mahadevan S, Saha M K and Chakravarty A R 2002 Inorg. Chem. 41 3469CrossRefGoogle Scholar
  22. 22.
    Hegg E L and Burstyn J N 1998 Coord. Chem. Rev. 173 133CrossRefGoogle Scholar
  23. 23.
    Mahadevan S and Palaniandavar M 1998 Inorg. Chem. 37 3927CrossRefGoogle Scholar
  24. 24.
    Palaniandavar M, Butcher R J and Addison A W 1996 Inorg. Chem. 35 467CrossRefGoogle Scholar
  25. 25.
    Uma Maheswari P and Palaniandavar M 2004 J. Inorg. Biochem. 98 219CrossRefGoogle Scholar
  26. 26.
    Tamilselvi P and Palaniandavar M 2002 Inorg. Chim. Acta 337 420CrossRefGoogle Scholar
  27. 27.
    Itoh K and Bernstein H J 1956 Can. J. Chem. 34 170CrossRefGoogle Scholar
  28. 28.
    Marmur J 1961 J. Mol. Biol. 3 208CrossRefGoogle Scholar
  29. 29.
    Huang G, Su C, Wang S, Liao F and Lin K 2000 J. Coord. Chem. 43 211CrossRefGoogle Scholar
  30. 30.
    (a) Palaniandavar M, Somasundaram I, Lakshminarayanan M and Manohar H 1996 J. Chem. Soc., Dalton Trans, 1333; (b) Tamil Seliv P, Murali M, Palaniandavar M, Cockerling M and Henkel G 2002 Inorg. Chim. Acta 340 139Google Scholar
  31. 31.
    Parkinson A, Hawken M, Hall M, Sanders K J and Rodger A 2000 Phys. Chem. Chem. Phys. 2 5469CrossRefGoogle Scholar
  32. 32.
    Barton J K, Danishefsky A T and Goldberg J M 1984 J. Am. Chem. Soc. 106 2127Google Scholar
  33. 33.
    Tysose S A, Morgan R J, Barker A D and Strekas T C 1993 J. Phys. Chem. 97 1707.CrossRefGoogle Scholar
  34. 34.
    Kelly T M, Tossi A B, Mckonnell D J and Strekas T C 1985 Nucleic Acid Res. 13 6017.CrossRefGoogle Scholar
  35. 35.
    Uma Maheswari P and Palaniandavar M 2004 Inorg. Chim. Acta 357 901CrossRefGoogle Scholar
  36. 36.
    Uma Maheswari P, Rajendiran V, Palaniandavar M, Parthasarathi R and Subramanian V Bull. Chem. Soc. Jpn (in press)Google Scholar
  37. 37.
    Norden B and Tjerneld T 1982 Biopolymers 21 1713CrossRefGoogle Scholar
  38. 38.
    Lerman L 1961 J. Mol. Biol. 3 18CrossRefGoogle Scholar
  39. 39.
    Raja A, Rajendiran V, Uma Maheswari P, Balamurugan R and Palaniandavar M (unpublished results)Google Scholar
  40. 40.
    Ivanov V I, Minchenkova L E, Schyolkina A K and Polytayer A I 1973 Biopolymers 12 89CrossRefGoogle Scholar
  41. 41.
    Collins J G, Shields T P and Barton J K 1994 J. Am. Chem. Soc. 116 9840CrossRefGoogle Scholar
  42. 42.
    Liu J G, Zhang Q L and Ji L N 2001 Transition Met. Chem. 26 733CrossRefGoogle Scholar
  43. 43.
    Mahadevan S and Palaniandavar M 1997 Inorg. Chim. Acta 254 291CrossRefGoogle Scholar
  44. 44.
    (a) Thomas T J and Bloomfield V A 1983 Nucleic Acids Res. 17 1919; (b) Gupta G, Dhingra M M and Sarna R H 1983 J. Biomol. Struct. Dyn. 12 89Google Scholar

Copyright information

© Indian Academy of Sciences 2005

Authors and Affiliations

  1. 1.School of ChemistryBharathidasan UniversityTiruchirappallliIndia

Personalised recommendations