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Three new bis(dithiocarbamato)copper(II) complexes have been prepared and characterized by elemental analysis, UV-Vis, and IR spectroscopy: bis(4-piperidonedithiocarbamato)copper(II), (Cu(Pdtc)2)2 (1), bis(piperidinedithiocarbamato)copper(II), (Cu(Ppdtc)2)2 (2), and bis((2-piperidinecarboxy)dithiocarbamato)copper(II), Cu(Ppidtc)2 (3). The crystal structures of the complexes 1 and 2 have been determined using X-ray diffraction methods and they are dimeric. The coordination sphere of copper(II) ions is described as a distorted square-pyramid: the axial Cu-S bond distances 2.7 and 2.8 Afor 1 and 2, respectively, are longer than the equatorial Cu-S ones (2.3 A ˚ ). Complexes 1 and 2 are not soluble in water. In contrast, 3 is water soluble. The interaction of 3, the previously prepared bis(N-(dithio- carboxy)sarcosine)copper(II), Cu(Sdtc)2 (4), and bis((dicarboxymethyl)dithiocarbamato)copper(II), Cu(Idadtc)2 (5), with nitric oxide in aqueous solution at pH 7.4 and 20 � C was spectrophotometrically studied and the experimental data were analysed by means of the SPEFO-LETAGROP and HYPERQUAD programs, respectively. The stability constants of the complexes CuL2(NO) and CuL2(NO)2 (L = dithio- carbamate) were determined. The interaction of 1 and 2 with nitric oxide was theoretically studied by molecular mechanics methods. Complexes 3, 4 and 5 and the previously studied bis((dihydroxyethyl)dithiocarbamato)copper(II), Cu(Deadtc)2 (6), decrease the NO pro- duced in vitro either by sodium nitroprusside (NPS) or by cultured murine macrophages J774 stimulated with lipopolysaccharide (LPS) and interferon-c (IFNc). Inducible nitric oxide synthase (iNOS) activity was determined by measuring the stable NO end product, nitrite, using a colorimetric assay. � 2006 Elsevier Ltd. All rights reserved. |
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