Characterization, Crystal Structure and Initial DNA Binding Mechanism Research of Multi‐nuclear Homometallic Complexes of 4,5‐Diazafluoren‐9‐one with Copper(II) and Cobalt(II)

Abstract

Two new multi-nuclear homometallic complexes, [Cu 2 (OAc) 4 (H 2 O) 2 ]•2dafo (1) and [(µ 2 -O) 2 -Co 3 (dafo) 6 ]-(ClO 3 ) 2 •H 2 O (2) (dafo＝4,5-diazafluoren-9-one), were synthesized. The two complexes have been fully characterized by elemental analysis, IR, absorption spectra, emission spectra, and single-crystal X-ray diffraction analysis. The initial DNA binding mechanisms of the two complexes have been investigated by absorption spectra, emission spectra and cyclic voltammograms. Both complexes show similar perturbations on addition of calf thymus DNA in the UV region, their luminescence intensities in aqueous buffer are all enhanced in the presence of increasing amounts of DNA, and their electrochemical behavior is both completely different in the absence and presence of DNA. The results of the three methods indicate that the spectral characters and the electrochemical behavior of the two complexes are very similar to those of the known metallointercalators. So it can be concluded that the action mode of the two complexes with DNA is mainly intercalative.

Pushing Single-Oxygen-Atom-Bridged Bimetallic Systems to the Right: A Cryptand-Encapsulated Co–O–Co Unit

“…The absence of well-characterized M–O–M systems for metals in the +2 formal oxidation state, and more generally, for total d electron counts >10, is a direct consequence of the electronic considerations embodied by the “oxo wall” . For metals right of the oxo wall, the M–O–M framework has been structurally characterized only for a Co and a Ni complex, and when the single O on Co is complexed by a Lewis acid . The zeolite catalysts Cu-ZSM-5 and Cu-MOR have been characterized as having [Cu 2 O] 2+ active sites that are formed upon either O 2 or N 2 O activation and are responsible for the selective oxidation of methane to methanol …”

Reduction of CO2 by a masked two-coordinate cobalt(i) complex and characterization of a proposed oxodicobalt(ii) intermediate

“…The presence of an oxo in 3 is particularly notable, given the paucity of cobalt( ii ) oxo complexes 17,18. Co III 2 (μ-O) 2 complexes have also been described 34,38.…”

“…Stauber et al presented a formally dianionic dicobalt( iii ) oxo species, for which XAS and computational results indicated an unusual electronic structure comprising two cobalt( ii ) ions, a bridging oxyl radical and an additional “hole” on the supporting ligand 17. The earlier example of a dicobalt oxo species by Zhang et al does not include sufficient spectroscopic details to establish the oxidation states of the metals 18. Thus, understanding the chemical behavior of dicobalt( ii ) oxo complexes remains elusive.…”

Evaluation of DNA-binding, radical scavenging and cytotoxic activity of five coordinated Cd(ii) complexes containing 2-acetylpyridine-N4-substituted thiosemicarbazone

“…The interaction of small molecules with DNA has been an active area of research at the interface of chemistry and biology. [1][2][3][4][5][6][7][8][9][10] These small molecules are stabilized in binding to DNA through a series of weak interactions, such as the p-stacking interactions associated with interacting with a planar aromatic group between the hydrogen-bonding of the base pairs, van der Waals interactions of functionalities bound along the groove of the DNA helix, 11 and the electrostatic interaction of the cation with the phosphate group of DNA. 12 Studies directed toward the design of site-and conformation-specific reagents provide a rational approach for new drug design as well as a means to develop sensitive chemical probes of nucleic acid structure.…”