Issue 21, 2012

Zinc(ii) complexes of constrained antiviral macrocycles

Abstract

The configurations of metallocyclams are of interest in relation to protein recognition and anti-HIV activity. We have synthesised four novel zinc(II) complexes with hexyl-Me2-cyclam (HMC; 3,14-dimethyl-2,6,13,17-tetraazatricyclo(16.4.0.07,12)docosane), 1, and naphthyl-hexyl-Me2-cyclam (NHMC; 2,13-bis(1-naphthylmethyl)-5,16-dimethyl-2,6,13,17-tetraazatricyclo(16.4.0.07,12)docosane), 2, as ligands. X-ray crystallographic data for Zn(II)–HMC diacetate, 3 show that zinc is six-coordinate in a distorted octahedral environment bound to four equatorial N atoms from the macrocycle and two axial acetato O atoms. The 14-membered metallo-macrocycle adopts a trans-III (RRSS) configuration with two six-membered rings in chair forms and two five-membered rings in gauche forms. In the chlorido Zn(II)–HMC complex 5, zinc appears to be 5-coordinate with square-pyramidal geometry. Interestingly, the chlorido Zn(II)–NHMC complex 6 crystallised in a trans-I configuration containing 4-coordinate tetrahedral zinc bound to three cyclam ring N atoms, a possible model for intermediates formed during the uptake and release of metals by cyclams. The ligand 1 and the zinc complex 3 were active towards viral strains HIV-1 (IIIB) (IC50 values of 10.51 ± 0.23 and 3.50 ± 0.33 μM, respectively), and HIV-2 (ROD) (IC50 values of 133.78 ± 14.10 and >110.67 μM, respectively). 2D [1H, 13C] and [1H, 15N] NMR spectroscopic studies suggested that the types of configurational isomers present in solution depend on the axial ligand.

Graphical abstract: Zinc(ii) complexes of constrained antiviral macrocycles

Supplementary files

Article information

Article type
Paper
Submitted
19 Jan 2012
Accepted
29 Feb 2012
First published
02 Apr 2012

Dalton Trans., 2012,41, 6408-6418

Zinc(II) complexes of constrained antiviral macrocycles

A. Ross, J. Choi, T. M. Hunter, C. Pannecouque, S. A. Moggach, S. Parsons, E. De Clercq and P. J. Sadler, Dalton Trans., 2012, 41, 6408 DOI: 10.1039/C2DT30140G

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