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Effects of Anthracene and Pyrene Units on the Interactions of Novel Polypyridylruthenium( II ) Mixed‐Ligand Complexes with DNA
Author(s) -
Mariappan Mariappan,
Maiya Bhaskar G.
Publication year - 2005
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200400952
Subject(s) - chemistry , phenanthroline , ruthenium , intercalation (chemistry) , ligand (biochemistry) , dna , pyrene , cyclic voltammetry , redox , anthracene , titration , stereochemistry , photochemistry , luminescence , bipyridine , base pair , crystallography , medicinal chemistry , inorganic chemistry , electrochemistry , organic chemistry , catalysis , biochemistry , physics , receptor , optoelectronics , electrode , crystal structure
2‐(9‐Anthryl)‐1 H ‐imidazo[4,5‐ f ][1,10]phenanthroline (aip) and [2‐(1‐pyrenyl)‐1 H ‐imidazo[4,5‐ f ][1,10]phenanthroline (pyip) and their complexes [Ru(phen) 2 (aip)] 2+ ( 1 ) and [Ru(phen) 2 (pyip)] 2+ ( 2 ) (phen = 1,10‐phenanthroline) have been synthesized and characterized by elemental analysis, UV/Vis, IR and 1 H NMR spectroscopy, FAB‐MS and cyclic voltammetry methods. Both 1 and 2 are redox‐active and undergo oxidation at 1.43 and 1.47 V (vs. SCE), respectively. Both 1 and 2 show only the 3 MLCT emission typical of any polypyridylruthenium( II ) complex. These new complexes are seen to be excellent binders of calf‐thymus (CT) DNA, as revealed by the results of absorption, luminescence, viscometric titrations, and thermal denaturation studies. These results also indicate that while ruthenium‐bound aip and pyip intercalate within the base pairs of the duplex, the phen moieties act only as spectator ligands in each case. Steady‐state emission studies carried out in aqueous media with and without DNA reveal that [Ru(phen) 2 (pyip)] 2+ is a better “molecular light switch” for DNA than [Ru(phen) 2 (aip)] 2+ . Under an identical set of experimental conditions of light and drug dose, the DNA photocleavage ability of [Ru(phen) 2 (pyip)] 2+ is also higher than that of [Ru(phen) 2 (aip)] 2+ . “Inhibitor studies” suggest that the oxygen species are mainly responsible for the DNA photocleavage by these complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)