title: Synthesis, characterization, and DNA-binding studies of nitro(oligopyridine)ruthenium(II) complexes.
abstract: The complexes of general formulas [RuII(terpy)(4-CO2H-4'-Mebpy)(X)]n+ (X = NO (n = 3) and NO2 (n = 1); 1, 2) and [RuII(terpy)(4-COGHK-4'-Mebpy)(X)] (X = NO (n = 3) and NO2 (n = 1); 3, 4) were synthesized and characterized. The complex [RuII(terpy)(4-CO2-4'-Mebpy)(NO2)]_7.5H2O has also been characterized by X-ray crystallographic studies. It crystallizes in the triclinic system: a = 9.4982(1) A, b = 13.1330(1) A, c = 14.2498(2) A; alpha = 110.5870(6) x bc, beta = 98.4048(5) x bc, gamma = 106.4353(5), P1, Z = 2. The crystal structure reveals an extended hydrogen-bonding network. Two water molecules form strong hydrogen bonds with the nitro and the carboxylic oxygen atoms of two separate units of the complex, resulting in a dimeric unit. The dimers are bridged by a (H2O)15 cluster, consisting of two cyclo-(H2O)6 species, while an exo-H2O(8) connects them. Two more exo-H2O molecules are joined together and connect the cyclo-(H2O)6 units with the H2O(1) of the dimeric unit. It was found that complexes 1 and 3 can be transformed into their nitro derivatives in aqueous media at neutral pH. Photorelease of NO in dry MeCN solutions was observed for complexes 1 and 3. Also, complex 2 partially releases (NO2)- in MeCN upon visible light irradiation. Complex 2 interacts with short fragments (70-300 bp) of calf thymus DNA shortening slightly the apparent polynucleotide length, while the conjugation of the peptide GHK to it (2) affects its DNA-binding mode. The peptide moiety of complex 4 was found to interact with the DNA helix in a synergistic way with the whole complex. Preliminary results of photocleavage of DNA by complex 2 are also reported.
authors.affiliation: Laboratory of Inorganic and General Chemistry, Department of Chemistry, University of Ioannina, Ioannina 45110, Greece.
authors.forename: Konstantina
authors.initials: K
authors.lastname: Karidi
authors.forename: Achilleas
authors.initials: A
authors.lastname: Garoufis
authors.forename: Nick
authors.initials: N
authors.lastname: Hadjiliadis
authors.forename: Martin
authors.initials: M
authors.lastname: Lutz
authors.forename: Anthony L
authors.initials: AL
authors.lastname: Spek
authors.forename: Jan
authors.initials: J
authors.lastname: Reedijk
mesh_terms: D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D009574:Nitro Compounds / Q000138:chemical synthesis*; D009942:Organometallic Compounds / Q000138:chemical synthesis*; D010777:Photochemistry; D011725:Pyridines / Q000138:chemical synthesis*; D012428:Ruthenium / Q000737:chemistry*; D013057:Spectrum Analysis; D014867:Water / Q000737:chemistry
chemical_list: D009574:Nitro Compounds; D009942:Organometallic Compounds; D011725:Pyridines; D014867:Water; D012428:Ruthenium; D004247:DNA; C427203:calf thymus DNA