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Synthesis and Biophysical Studies of Bis‐Macrocyclic Cobalt/Copper(II) Complexes Having a Pyridine Spacer with CT DNA and 5′‐GMP
Author(s) -
Arjmand Farukh,
Aziz Mubashira
Publication year - 2009
Publication title -
chemistry and biodiversity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 70
eISSN - 1612-1880
pISSN - 1612-1872
DOI - 10.1002/cbdv.200800282
Subject(s) - chemistry , crystallography , ethidium bromide , cobalt , copper , titration , octahedral molecular geometry , metal , cyclic voltammetry , pyridine , molar conductivity , binding constant , absorption (acoustics) , electron paramagnetic resonance , intercalation (chemistry) , molecule , proton nmr , coordination geometry , dna , inorganic chemistry , stereochemistry , binding site , electrochemistry , medicinal chemistry , crystal structure , organic chemistry , nuclear magnetic resonance , hydrogen bond , acoustics , biochemistry , physics , electrode
New bis‐macrocyclic complexes of Co III , 1 , Ni II , 2 , and Cu II , 3 , containing pyridyl bridges between 13‐membered macrocyclic subunits, have been synthesized via an in situ one‐pot template condensation reaction (IOPTCR). The proposed structures of these new dinuclear complexes are consistent with the data obtained from elemental analysis, molar conductance, IR, EPR, UV/VIS, 1 H‐ and 13 C‐NMR, and ESI‐MS. The complexes 2 and 3 possess square‐planar geometry with four secondary N‐atoms coordinated to the metal ion, while complex 1 reveals octahedral geometry in solution due to coordinated H 2 O molecules. DNA‐Binding properties of the complexes 1 and 3 were investigated by absorption and emission titrations, cyclic voltammetry, and viscosity measurements. Complexes 1 and 3 are strong DNA binders with binding constants, K b , of 1.64×10 5 and 2.05×10 5 M −1 , respectively. Hyperchromism, decrease in emission intensity of DNA‐bound ethidium bromide (EB), and changes observed in the viscosity and cyclic voltammograms in the presence of added metal complexes reveals that the complexes bind to DNA predominantly by electrostatic attraction, substantiated by absorption titration with 5′‐GMP.