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Effect of Substitution Pattern of Ancillary Ligands on the DNA‐Binding Behavior of Two New Ru II –Polypyridyl Complexes
Author(s) -
Tan LiFeng,
Liu JianHua,
Wang Fang,
Zhang Sheng
Publication year - 2007
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.200790236
Subject(s) - chemistry , intercalation (chemistry) , steric effects , dna , ligand (biochemistry) , circular dichroism , stereochemistry , phenanthroline , fluorescence , crystallography , receptor , biochemistry , inorganic chemistry , physics , quantum mechanics
The new ligand 2‐(4‐phenoxyphenyl)‐1 H ‐imidazo[4,5‐ f ][1,10]phenanthroline (ppip) and its Ru II complexes [Ru(2,9‐dmp) 2 (ppip)] 2+ ( 1 ) and [Ru(4,7‐dmp) 2 (ppip)] 2+ ( 2 ; 2,9‐ and 4,7‐dmp=2,9‐ and 4,7‐dimethyl‐1,10‐phenanthroline, resp.) were synthesized and characterized. The binding properties of the two complexes towards calf‐thymus DNA (CT‐DNA) in buffered H 2 O (pH 7.2) were investigated by different spectrophotometric methods and viscosity measurements. Both 1 and 2 strongly bind to CT‐DNA by means of intercalation, but with different binding strengths. In contrast to the more tightly bound complex 2 , the sterically more‐demanding complex 1 showed no fluorescence emission, neither alone nor in the presence of CT‐DNA. Our results demonstrate that the position of Me groups on phenanthroline (phen) ancillary ligands significantly affects the overall DNA‐recognition propensities of Ru II –polypyridyl complexes. Further, the partly resolved complex 2 was shown by circular dichroism (CD) to stereoselectively recognize CT‐DNA, in contrast to 1 .