title: Intercalation of fac-[(4,4'-bpy)ReI(CO)3(dppz)]+, dppz = dipyridyl[3,2-a:2'3'-c]phenazine, in polynucleotides. On the UV-vis photophysics of the Re(I) intercalator and the redox reactions with pulse radiolysis-generated radicals.
abstract: The intercalation of fac-[(4,4'-bpy)Re(I)(CO)3(dppz)]+ (dppz = dipyridyl[3,2-a:2'3'-c]phenazine) in polynucleotides, poly[dAdT]2 and poly[dGdC]2, where A = adenine, G = guanine, C = cytosine and T = thymine, is a major cause of changes in the absorption and emission spectra of the complex. A strong complex-poly[dAdT]2 interaction drives the intercalation process, which has a binding constant, Kb approximately 1.8 x 10(5) M(-1). Pulse radiolysis was used for a study of the redox reactions of e(-)(aq), C*H(2)OH and N3* radicals with the intercalated complex. These radicals exhibited more affinity for the intercalated complex than for the bases. Ligand-radical complexes, fac-[(4,4'-bpy*)Re(I)(CO)3(dppz)] and fac-[(4,4'-bpy)Re(I)(CO)3(dppz *)], were produced by e(-)(aq) and C*H(2)OH, respectively. A Re(II) species, fac-[(4,4'-bpy)Re(II)(CO)3(dppz)](2+), was produced by N3* radicals. The rate of annihilation of the ligand-radical species was second order on the concentration of ligand-radical while the disappearance of the Re(II) complex induced the oxidative cleavage of the polynucleotide strand.
authors.affiliation: INIFTA, Universidad Nacional de La Plata, C. C. 16, Suc. 4, 1900, La Plata, Argentina.
authors.forename: G T
authors.initials: GT
authors.lastname: Ruiz
authors.forename: M P
authors.initials: MP
authors.lastname: Juliarena
authors.forename: R O
authors.initials: RO
authors.lastname: Lezna
authors.forename: E
authors.initials: E
authors.lastname: Wolcan
authors.forename: M R
authors.initials: MR
authors.lastname: Feliz
authors.forename: G
authors.initials: G
authors.lastname: Ferraudi
mesh_terms: D015082:2,2'-Dipyridyl / Q000737:chemistry*; D004563:Electrochemistry; D005609:Free Radicals / Q000737:chemistry*; D007364:Intercalating Agents / Q000737:chemistry*; D008024:Ligands; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010619:Phenazines / Q000737:chemistry*; D010777:Photochemistry; D011119:Polynucleotides / Q000737:chemistry*; D011675:Pulse Radiolysis; D012211:Rhenium / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D014466:Ultraviolet Rays
chemical_list: D005609:Free Radicals; D007364:Intercalating Agents; D008024:Ligands; D009942:Organometallic Compounds; D010619:Phenazines; D011119:Polynucleotides; D015082:2,2'-Dipyridyl; D012211:Rhenium