Chandrasekhar, Vadapalli ; Azhakar, Ramachandran ; Senapati, Tapas ; Thilagar, Pakkirisamy ; Ghosh, Surajit ; Verma, Sandeep ; Boomishankar, Ramamoorthy ; Steiner, Alexander ; Kögerler, Paul (2008) Synthesis, structure, magnetism and nuclease activity of tetranuclear copper(II) phosphonates containing ancillary 2,2'-bipyridine or 1,10-phenanthroline ligands Dalton Transactions (9). pp. 1150-1160. ISSN 0300-9246
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Official URL: http://pubs.rsc.org/en/Content/ArticleLanding/2008...
Related URL: http://dx.doi.org/10.1039/B712876B
Abstract
The reaction of cyclohexylphosphonic acid (C6H11PO3H2), anhydrous CuCl2 and 2,2'-bipyridine (bpy) in the presence of triethylamine followed by a metathesis reaction with KNO3 afforded [Cu4(μ-Cl)2(μ3-C6H11PO3)2(bpy)4](NO3)2 (1). In an analogous reaction involving Cu(OAc)2·H2O, the complex [Cu4(μ-CH3COO)2(μ3-C6H11PO3)2(2,2'-bpy)4](CH3COO)2 (2) has been isolated. The three-component reaction involving Cu(NO3)2·3H2O, cyclohexylphosphonic acid and 2,2'-bipyridine in the presence of triethylamine afforded the tetranuclear assembly [Cu4(μ-OH)(μ3-C6H11PO3)2(2,2'-bpy)4 (H2O)2](NO3)3 (3). Replacing 2,2'-bipyridine with 1,10-phenanthroline (phen) in the above reaction resulted in [Cu4(μ-OH)(μ3-C6H11PO3)2(phen)4(H2O)2](NO3)3 (4). In all the copper(II) phosphonates (1-4) the two phosphonate ions bridge the four copper(II) ions in a capping coordination action. Each phosphonate ion bridges four copper(II) ions in a μ4, η3 coordination mode or 4.211 of the Harris notation. Variable-temperature magnetic studies on 1-4 reveal that all four complexes exhibit moderately strong intramolecular antiferromagnetic coupling. The DNA cleavage activity of complexes 1-4 is also described. Compounds 1 and 3 were able to completely convert the supercoiled pBR322 DNA form I to nick form II without any co-oxidant. In contrast, 50% conversion occurred with 2 and 40% with 4. In the presence of magnesium monoperoxyphthalate all four compounds achieved rapid conversion of form I to form II.
| Item Type: | Article |
|---|---|
| Source: | Copyright of this article belongs to Royal Society of Chemistry. |
| ID Code: | 66187 |
| Deposited On: | 21 Oct 2011 09:59 |
| Last Modified: | 13 Jul 2012 14:38 |
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