X-ray crystal structure of tetrakis(1-methylcytosine)copper(II) perchlorate dihydrate: effect of 1-methyl substitution on cytosine on the spectral and redox behaviour

Complex Formation of Nickel(II) with Sugar Residues, Nucleobases, Phosphates, Nucleotides, and Nucleic Acids

“…(ii) The data point for the Ni(Cyd) 2ϩ complex [82] fi ts on the reference line defi ned by the M(oPyN) 2ϩ species, meaning that the neighboring carbonyl group does not participate in metal ion binding and that only the steric inhibition of the (C6)NH 2 group is in action. (iii) This is different for the Cu(Cyd) 2ϩ complex which shows an increased complex stability thus indicating the participation of the (C2)O group in metal ion binding in accord with the mentioned X-ray study [81]. In other words, the steric inhibiting effect of the (C6)NH 2 group is partially offset by the (C2)O group.…”

“…It is important to emphasize in this context the ambivalent properties of the cytosine moiety as revealed by crystal structure studies: In the dimeric [(En)Pt(CMP)] 2 complex the square plane around (En)Pt 2ϩ is completed by N3 of one CMP 2Ϫ and a phosphate oxygen of the other [48,79], whereas in Ba(CMP) • 8.5H 2 O the alkaline earth metal ion is bonded to (C2)O (and the sugar, but not the phosphate) [48,80]. Between these two 'extremes' are cases where both N3 and (C2)O participate as, e.g., in the tetrakis(1-methylcytosine)- [81]. Here, the four N3 atoms of the nucleobases form a CuN 4 plane (mean Cu-N distance 2.03 Å) with more weakly bound C2 carbonyls (mean 2.73 Å) above and below this plane.…”

Structures, spectra, and DNA-binding properties of mixed ligand copper(II) complexes of iminodiacetic acid: The novel role of diimine co-ligands on DNA conformation and hydrolytic and oxidative double strand DNA cleavage

“…The frozen solution EPR spectra of the complexes are axial with g i > g^> 2.0 and G = [(g i À 2)/ (g^À 2)] = 3.6 suggesting that the nearly square-based geometries observed in the solid state are retained in solution. Further, a square-based CuN 4 chromophore is expected [45,46] to show a g i value of 2.200 and an A i value of 180-200 · 10 À4 cm À1 (Table 3) and the replacement of nitrogen atom in this chromophore by an oxygen atom is expected to increase the g i value and decrease the A i value. On the other hand, incorporation of strong axial interaction as in the present complexes would increase the g i and decrease the A i values.…”

The replacement of chlorides by cytosines in copper(II) complexes containing guanidine derivatives

“…These activities have guided us to prepare copper(II) complexes containing a CuN 2 Cl 2 chromophore analog to cisplatin and then to study their interactions with DNA nucleobases. Several studies have mainly focused on the direct interaction of metal salts, where M = Cu, Rh, Cd, Mn or Co, with the cytosine nucleobase and its derivative 1-methylcytosine [12][13][14][15][16][17][18][19], but not the direct nucleobase replacement of the anionic ligands on metal complexes like the cisplatin system. However, Reedijk and coworkers have studied on interactions of the octahedral ruthenium(II) complexes [cis-Ru(bpy) 2 Cl 2 ] [20] and [a-Ru(azpy) 2 -(NO 3 ) 2 ] [21] (bpy = 2,2 0 -bipyridine and azpy = 2-(phenylazo)pyridine) with 9-ethylguanine, 9-methylhypoxanthine and guanosine, which replace only one of the two anionic ligands to yield the monofunctional binding adducts.…”