Issue 9, 2008

Synthesis, structure, magnetism and nuclease activity of tetranuclear copper(ii) phosphonates containing ancillary 2,2′-bipyridine or 1,10-phenanthroline ligands

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)23-C6H11PO3)2(bpy)4](NO3)2 (1). In an analogous reaction involving Cu(OAc)2·H2O, the complex [Cu4(µ-CH3COO)23-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.

Graphical abstract: Synthesis, structure, magnetism and nuclease activity of tetranuclear copper(ii) phosphonates containing ancillary 2,2′-bipyridine or 1,10-phenanthroline ligands

Supplementary files

Article information

Article type
Paper
Submitted
21 Aug 2007
Accepted
16 Nov 2007
First published
07 Jan 2008

Dalton Trans., 2008, 1150-1160

Synthesis, structure, magnetism and nuclease activity of tetranuclear copper(II) phosphonates containing ancillary 2,2′-bipyridine or 1,10-phenanthroline ligands

V. Chandrasekhar, R. Azhakar, T. Senapati, P. Thilagar, S. Ghosh, S. Verma, R. Boomishankar, A. Steiner and P. Kögerler, Dalton Trans., 2008, 1150 DOI: 10.1039/B712876B

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements