Synthesis, spectroscopic studies of new water-soluble Co(II) and Cu(II) macrocyclic complexes of 4,15-bis(2-hydroxyethyl)-2,4,6,13,15,17-hexaazatricyclodocosane: their interaction studies with calf thymus DNA and guanosine 5′ monophosphate

  • Farukh ArjmandEmail author
  • Mubashira Aziz
  • Mala Chauhan
Original Article


New water soluble Co(II) 1, Ni(II) 2 and Cu(II) 3 complexes of 4,15-bis(2-hydroxyethyl)-2,4,6,13,15,17-hexaazatricyclodocosane Co(II) were synthesized and characterized by various techniques, viz. elemental analysis, conductivity measurements, infrared, electronic, ESI-MS, 1H and 13C NMR spectroscopy. Molar conductance measurements in aqueous solution showed that complexes 1, 2 and 3 are ionic in nature. On the basis of spectroscopic data, a square planar geometry was assigned to the complexes involving four N-atoms of the two cyclohexane moieties. Interaction studies of 1 and 3 with CT-DNA were carried using UV/Visible absorption spectroscopy, fluorescence spectrophotometry, cyclic voltammetry and viscosity measurements. Absorption spectral traces reveal 27.7 and 23.3% hyperchromism for complexes 1 and 3, respectively indicative of strong binding to CT-DNA. These results were authenticated by fluorescence quenching experiments and viscosity measurements. The intrinsic binding constants K b of 1 and 3 are 2.94 × 104 and 2.71 × 104 M−1, respectively. Early transition metals show preference for O6 position while later ones copper and cobalt prefer N7 position of DNA base guanine. To validate this hypothesis, interaction studies of copper (II) and cobalt (II) complexes were carried out with 5′GMP, which revealed electrostatic interactions are more favored along with hydrogen bonding than coordinate covalent interaction to N7 position of guanine.


Binding studies CT-DNA 5′GMP binding studies NMR and UV/vis Fluorescence Macrocyclic complexes 



Calf thymus DNA


Cyclic voltammetry




Ethidium bromide


5′Guanosine monophosphate


Ligand field





The authors are grateful to Council of Scientific and Industrial Research, New Delhi, India for generous financial support (Scheme No. 01 (1982)/05-EMR-II). Thanks to Regional Sophisticated Instrumentation Center, Central Drug Research Institute, Lucknow, India for providing elemental analysis, ESI-MS and NMR, Indian Institute of Technology Bombay, Mumbai, India for EPR measurements and Sophisticated Analytical Instrumentation Facility, Punjab University, Chandigarh, India for running the NMR experiments.


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© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  1. 1.Department of ChemistryAligarh Muslim UniversityAligarhIndia

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