title: Efficient DNA binding by optically Pure Ruthenium Tris(bipyridyl) complexes incorporating carboxylic functionalities. Solution and structural analysis.
abstract: Herein, we report on the binding of optically pure ruthenium complexes Delta- or Lambda-[Ru(bpy)(2)(L-L)][PF(6)](2) [L-L = Hcmbpy = 4-carboxy-4'-methyl-2,2'-bipyridine (1), L-L = H(2)dcbpy = 4,4'-dicarboxy-2,2'-bipyridine (2)] to DNA. The binding constants of the two enantiomeric Delta-1 and Lambda-1 complexes to DNA were estimated from titration monitored by (1)H NMR spectroscopy. 2D transferred NOESY (TRNOESY) experiments support the conclusion that Delta-1 and Lambda-1 bind to DNA and that an intermediate-to-fast exchange occurs between bound and free Ru(II) complex. Further, evidence for enantioselective DNA cleavage by Delta-2 is provided by means of gel electrophoresis performed in the presence and in the absence of light; in contrast, the Lambda-2 enantiomer does not. The IR spectrum of enantiomer Delta-2 (or Lambda-2) compared to that of the racemate (rac-2) gives evidence that, in the latter form, the enantiomers are strongly associated. Moreover the X-ray structure of rac-2 was also determined and exhibits as an outstanding feature the formation of a one-dimensional supramolecular species in which the cohesion of the system is maintained by strong hydrogen bonding between carboxylic acid groups of enantiomers Delta-2 and Lambda-2 (cationic parts) with d(O...O) = 2.6 A in agreement with the infrared results. The conclusion that can be drawn from IR and X-ray spectroscopies together is that the self-association in rac-2 is strong.
authors.affiliation: Université Paris 6, Pierre et Marie Curie, 4 place Jussieu, case 42, 75252 Paris Cedex 05, France.
authors.forename: Régis
authors.initials: R
authors.lastname: Caspar
authors.forename: Léna
authors.initials: L
authors.lastname: Musatkina
authors.forename: Alexander
authors.initials: A
authors.lastname: Tatosyan
authors.forename: Hani
authors.initials: H
authors.lastname: Amouri
authors.forename: Michel
authors.initials: M
authors.lastname: Gruselle
authors.forename: Carine
authors.initials: C
authors.lastname: Guyard-Duhayon
authors.forename: Raphaël
authors.initials: R
authors.lastname: Duval
authors.forename: Christine
authors.initials: C
authors.lastname: Cordier
mesh_terms: D015082:2,2'-Dipyridyl / Q000737:chemistry*; D000465:Algorithms; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013237:Stereoisomerism
chemical_list: D009942:Organometallic Compounds; D015082:2,2'-Dipyridyl; D012428:Ruthenium; D004247:DNA