Issue 9, 2004

Nickel(ii), copper(ii) and zinc(ii) binding properties and cytotoxicity of tripodal, hexadentate tris(ethylenediamine) – analogue chelators

Abstract

Three tripodal hexamine chelators based on cis,cis-1,3,5-triaminocyclohexane (tach) have been synthesized and their aqueous coordination chemistry with Ni(II), Cu(II) and Zn(II) is reported. The chelators have a 2-aminoethyl pendant arm attached to each nitrogen of tach, specifically ‘tachen’ (N,N′,N″-tris(2-aminoethyl)cyclohexane-cis,cis-1,3,5-triamine), and two with S,S,S-chiral pendant arms, ‘tachpn’ (N,N′,N″-tris(2-aminopropyl)cyclohexane-cis,cis-1,3,5-triamine) and ‘tachbn’ (N,N′,N″-tris(2-amino-3-phenylpropyl)cyclohexane-cis,cis-1,3,5-triamine. These chelators complex Ni(II), Cu(II) and Zn(II) in aqueous or aqueous/methanolic medium. The crystalline products [MIIL](X)2 are isolated, where M = Ni(II), Cu(II) or Zn(II), L = tachen, tachpn or tachbn, and X = ClO4. Crystallographic study of selected tachpn and tachbn complexes shows the chelate arms are constrained in a Λ(δδδ) configuration about M(II), which is attributed to their chirality. Solution UV-vis spectroscopy of the Ni(II) and Cu(II) complexes indicates six-coordination and little effect of the pendant arm substitution on ligand-field strength. The single exception is [Cu(tachbn)]2+, whose spectrum is consistent with five-coordination in solution. The cytotoxicities of tachen, tachpn and tachbn toward cultured cancer cells is in the order tachen < tachpn < tachbn < tachpyr, where tachpyr is the aminopyridyl chelator N,N′,N″-tris(2-pyridylmethyl)cyclohexane-cis,cis-1,3,5-triamine. The cytotoxicity difference is attributed to an order of increasing lipophilicity, tachen < tachpn < tachbn.

Graphical abstract: Nickel(ii), copper(ii) and zinc(ii) binding properties and cytotoxicity of tripodal, hexadentate tris(ethylenediamine) – analogue chelators

Supplementary files

Article information

Article type
Paper
Submitted
05 Mar 2004
Accepted
10 Mar 2004
First published
31 Mar 2004

Dalton Trans., 2004, 1304-1311

Nickel(II), copper(II) and zinc(II) binding properties and cytotoxicity of tripodal, hexadentate tris(ethylenediamine) – analogue chelators

N. Ye, G. Park, A. M. Przyborowska, P. E. Sloan, T. Clifford, C. B. Bauer, G. A. Broker, R. D. Rogers, R. Ma, S. V. Torti, M. W. Brechbiel and R. P. Planalp, Dalton Trans., 2004, 1304 DOI: 10.1039/B403476G

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