RSC Publishing


Publishing

 

Cover image for Dalton Transactions, select for current issue

Dalton Transactions

The international journal for inorganic, organometallic and bioinorganic chemistry



Subscribers

Non-subscribers

Free access



Paper

Dalton Trans., 2009, 9183 - 9191, DOI: 10.1039/b909249h

Interaction with DNA of a heteronuclear [Na2Cu4] coordination cluster obtained from the assembly of two hydroxo-bridged [CuII2] units by a dimeric sodium nitrate template

Debashree Mandal, Mala Chauhan, Farukh Arjmand, Guillem Aromí and Debashis Ray

The heteronuclear [Na2Cu4(bemp)2(OH)2(NO3)2(OH2)4]·5H2O ( 1·5H2O; H3bemp: 2,6-bis-[(2-hydroxyethylimino)-methyl]-4-methyl-phenol) cluster has been synthesized in aqueous-methanol at room temperature and structurally characterized. The water soluble complex is obtained from the template assembly of two [Cu2(bemp)(OH)] neutral fragments through their weak oxophillic interactions with two interconnected NaNO3 units as core. Four [Na2Cu4] units form a metal–organic cage arrangement in the crystal lattice that traps a (H2O)7 cluster. Variable-temperature magnetic susceptibility measurements (2–300 K) reveals a strong antiferromagnetic coupling between the CuII ions within the dimers with J = -124.1 cm-1 (in the H = -2JS1S2 convention). The interaction of complex 1·3H2O with calf thymus DNA (binding constant Kb, 4.6 × 104 M-1) in Tris buffer was studied by UV-visible and emission titration, and cyclic voltammetry. The hexanuclear Na2Cu4 complex also binds double-stranded supercoiled plasmid pBR322 DNA and displays efficient hydrolytic cleavage. The hydrolytic mechanism is supported by evidence from DNA relegation employing T4 ligase assay and reactive oxygen species (ROS) quenching cleavage experiments.

Graphical abstract image for this article (ID: b909249h)