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Synthesis and characterization of dinuclear macrocyclic cobalt(II), copper(II) and zinc(II) complexes derived from 2,2,2 ′,2 ′- S, S[bis(bis- N, N-2-thiobenzimidazolyloxalato-1,2-ethane)]: DNA binding and cleavage studies
Ist Teil von
European journal of medicinal chemistry, 2009-02, Vol.44 (2), p.834-844
Ort / Verlag
Kidlington: Elsevier Masson SAS
Erscheinungsjahr
2009
Link zum Volltext
Quelle
Elsevier ScienceDirect Journals Complete
Beschreibungen/Notizen
New homodinuclear macrocyclic complexes of cobalt(II), copper(II) and zinc(II) were isolated from the newly synthesized ligand 2,2,2′,2′-
S,
S[bis(bis-
N,
N-2-thiobenzimidazolyloxalato-1,2-ethane)]. The structures of the complexes were elucidated by elemental analysis, molar conductance measurements, IR,
1H NMR,
13C NMR, electronic and ESI-MS spectroscopic techniques. In complex
1, Co(II) ions possess a tetrahedral coordination environment composed of O
2S
2 donor atoms while its Cu(II) and Zn(II) counterparts
2 and
3, respectively, reveal a six coordinate octahedral structure, defined by the O
2S
2 donors from the macrocyclic ring and two chloride ions. Molar conductance and spectroscopic data also support the proposed geometry of the complexes. DNA binding properties of complexes
1–
3 were investigated using electronic absorption spectroscopy, fluorescence spectroscopy, viscosity measurements and cyclic voltammetry. The absorption spectra of complexes
2 and
3 with calf thymus DNA showed hypochromism, while complex
1 showed hyperchromism attributed to a partial intercalation and electrostatic binding modes, respectively. The intrinsic binding constant
K
b of complexes
1–
3 were determined as 16.6
×
10
4
M
−1, 4.25
×
10
4
M
−1 and 3.0
×
10
4
M
−1, respectively. The decrease in the relative specific viscosity of calf thymus DNA with increasing concentration of the complexes authenticates the partial intercalation binding mode. Gel electrophoresis of complex
2 with plasmid DNA demonstrated that complex exhibits excellent “artificial” nuclease activity.
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