title: DNA binding by Ru(II)-bis(bipyridine)-pteridinyl complexes.
abstract: The interactions of five bis(bipyridyl) Ru(II) complexes of pteridinyl-phenanthroline ligands with calf thymus DNA have been studied. The pteridinyl extensions were selected to provide hydrogen-bonding patterns complementary to the purine and pyrimidine bases of DNA and RNA. The study includes three new complexes [Ru(bpy)(2)(L-pterin)](2+), [Ru(bpy)(2)(L-amino)](2+), and [Ru(bpy)(2)(L-diamino)](2+) (bpy is 2,2'-bipyridine and L-pterin, L-amino, and L-diamino are phenanthroline fused to pterin, 4-aminopteridine, and 2,4-diaminopteridine), two previously reported complexes [Ru(bpy)(2)(L-allox)](2+) and [Ru(bpy)(2)(L-Me(2)allox)](2+) (L-allox and L-Me(2)allox are phenanthroline fused to alloxazine and 1,3-dimethyalloxazine), the well-known DNA intercalator [Ru(bpy)(2)(dppz)](2+) (dppz is dipyridophenazine), and the negative control [Ru(bpy)(3)](2+). Reported are the syntheses of the three new Ru-pteridinyl complexes and the results of calf thymus DNA binding experiments as probed by absorption and fluorescence spectroscopy, viscometry, and thermal denaturation titrations. All Ru-pteridine complexes bind to DNA via an intercalative mode of comparable strength. Two of these four complexes--[Ru(bpy)(2)(L-pterin)](2+) and [Ru(bpy)(2)(L-allox)](2+)--exhibit biphasic DNA melting curves interpreted as reflecting exceptionally stable surface binding. Three new complexes--[Ru(bpy)(2)(L-diamino)](2+), [Ru(bpy)(2)(L-amino)](2) and [Ru(bpy)(2)(L-pterin)](2+)--behave as DNA molecular "light switches."
authors.affiliation: Department of Chemistry, Bryn Mawr College, Bryn Mawr, PA 19010, USA.
authors.forename: Shannon R
authors.initials: SR
authors.lastname: Dalton
authors.forename: Samantha
authors.initials: S
authors.lastname: Glazier
authors.forename: Belinda
authors.initials: B
authors.lastname: Leung
authors.forename: Sanda
authors.initials: S
authors.lastname: Win
authors.forename: Courtney
authors.initials: C
authors.lastname: Megatulski
authors.forename: Sharon J Nieter
authors.initials: SJ
authors.lastname: Burgmayer
mesh_terms: D015082:2,2'-Dipyridyl / Q000737:chemistry*; D000042:Absorption; D000818:Animals; D002417:Cattle; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry*; D046032:Microscopy, Energy-Filtering Transmission Electron; D009691:Nucleic Acid Denaturation; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011621:Pteridines / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D055672:Static Electricity; D044366:Transition Temperature
chemical_list: D009942:Organometallic Compounds; D011621:Pteridines; D015082:2,2'-Dipyridyl; D012428:Ruthenium; D004247:DNA; C427203:calf thymus DNA