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DNA Binding of an Organic dppz-Based Intercalator

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posted on 02.11.2004, 00:00 by Tim Phillips, Ihtshamul Haq, Anthony J. H. M. Meijer, Harry Adams, Ian Soutar, Linda Swanson, Matthew J. Sykes, Jim A. Thomas
An improved synthesis of a water-soluble derivative of dipyrido[3,2-a:2‘,3‘-c]phenazine (dppz) is reported. The structures of both dppz and the cation ethylene-bipyridyldiylium-phenazine dinitrate {[1][(PF6)2]} have been obtained via X-ray crystallography. Metal complex derivatives of dppz are very well studied. However, using the water soluble [1][(NO3)2], the nature of the interaction of a simple dppz unit with duplex DNA has been investigated for the first time. In both organic solvents and water, 1 displays unstructured luminescence, assigned to an intramolecular charge transfer. The emission is quenched on binding to natural and synthetic duplex DNA, including poly(dA)·poly(dT). A variety of techniques reveal that the cation binds to DNA with an affinity comparable to those of many metal dppz complexes, via an intercalative binding mode.