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Mixed-ligand copper(II) complexes of dipicolylamine and 1,10phenanthrolines: The role of diimines in the interaction of the
complexes with DNA
By:Ramakrishnan, S (Ramakrishnan, S); Palaniandavar, M (Palaniandavar, M)
JOURNAL OF CHEMICAL SCIENCES
Volume: 117
Issue: 2
Pages: 179-186
Published: MAR 2005
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Abstract
Mixed-ligand copper(II) complexes of the type [Cu(dipica)(diimine)](ClO4)(2), where dipica is di(2picolyl)amine and diimine is 1,10-phenanthroline (phen), 5,6-dimethyl-1,10-phenanthroline (5,6dmp),
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(parallel to)
and All values of similar to 2-22 and 185 x 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.
Keywords
Author Keywords:mixed-ligand Cu(II) complexes; dipica and 1,10-phenanthrolines; DNA binding
studies; CD spectroscopy
KeyWords Plus:CALF THYMUS DNA; RUTHENIUM(II) COMPLEXES; CIRCULARDICHROISM; NUCLEASE ACTIVITY; CLEAVAGE
ACTIVITY; BINDING;ACID; PHOTOCLEAVAGE; SPECTROSCOPY; TRANSITION
Author Information
Reprint Address: Palaniandavar, M (reprint author)
Bharathidasan Univ, Sch Chem, Tiruchchirappalli 620024, India.
Addresses:
[ 1 ] Bharathidasan Univ, Sch Chem, Tiruchchirappalli 620024, India
E-mail Addresses:[email protected]
Publisher
INDIAN ACADEMY SCIENCES, C V RAMAN AVENUE, SADASHIVANAGAR, P B #8005,
BANGALORE 560 080, INDIA
Categories / Classification
Research Areas:Chemistry
Web of Science Categories:Chemistry, Multidisciplinary
Document Information
Document Type:Article
Language:English
Accession Number: WOS:000228233400016
ISSN: 0253-4134
Other Information
IDS Number: 914NB
Cited References in Web of Science Core Collection: 46
Times Cited in Web of Science Core Collection: 71