Dioxo- and Oxovanadium(V) Complexes of Thiohydrazone ONS Donor Ligands: Synthesis, Characterization, Reactivity, and Antiamoebic Activity
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- 作者：Mannar R. Maurya ; Amit Kumar ; Abdul R. Bhat ; Amir Azam ; Cerstin Bader ; and Dieter Rehder
- 刊名：Inorganic Chemistry
- 出版年：2006
- 出版时间：February 6, 2006
- 年：2006
- 卷：45
- 期：3
- 页码：1260 - 1269
- 全文大小：156K
- 年卷期：v.45,no.3(February 6, 2006)
- ISSN：1520-510X
文摘
As a contribution to the development of novel vanadium complexes with pharmacologically interesting properties,two neutral dioxovanadium(V) complexes [VO2(Hpydx-sbdt)] (1) and [VO2(Hpydx-smdt)] (3) [H2pydx-sbdt (I) andH2pydx-smdt (II) are the Schiff bases derived from pyridoxal and S-benzyl- or S-methyldithiocarbazate] have beensynthesized by the reaction of [VO(acac)2] and the potassium salts of the ligands in methanol followed by aerialoxidation. Heating of the methanolic solutions of these complexes yields the oxo-bridged binuclear complexes[{VO(pydx-sbdt)}2
-O] (2) and [{VO(pydx-smdt)}2-O] (4). The crystals and molecular structures of 1, 3·1.5H2O,and 4·2CH3OH have been determined, confirming the ONS binding mode of the dianionic ligands in their thioenolateform. The ring nitrogen of the pyridoxal moiety is protonated in complexes 1 and 3. Acidification of 1 and 3 withHCl dissolved in methanol afforded oxohydroxo complexes, while in a methanolic KOH solution, the correspondingdioxo species K[VO2(pydx-sbdt/smdt)] are formed. Treatment of 1 and 3 with H2O2 yields (unstable) oxoperoxovanadium(V) complexes, the formation of which has been established spectrophotometrically. In vitro antiamoebicactivities (against HM1:1MSS strain of Entamoeba histolytica) were established for all of the dioxo- and oxovanadium(V) complexes. The complexes 1, 2, and 4 were more effective than metronidazole, a commonly used drug againstamoebiasis, suggesting that oxovanadium(V) complexes derived from thiohydrazones may open a new dimensionin the therapy of amoebiasis.
-O] (2) and [{VO(pydx-smdt)}2-O] (4). The crystals and molecular structures of 1, 3·1.5H2O,and 4·2CH3OH have been determined, confirming the ONS binding mode of the dianionic ligands in their thioenolateform. The ring nitrogen of the pyridoxal moiety is protonated in complexes 1 and 3. Acidification of 1 and 3 withHCl dissolved in methanol afforded oxohydroxo complexes, while in a methanolic KOH solution, the correspondingdioxo species K[VO2(pydx-sbdt/smdt)] are formed. Treatment of 1 and 3 with H2O2 yields (unstable) oxoperoxovanadium(V) complexes, the formation of which has been established spectrophotometrically. In vitro antiamoebicactivities (against HM1:1MSS strain of Entamoeba histolytica) were established for all of the dioxo- and oxovanadium(V) complexes. The complexes 1, 2, and 4 were more effective than metronidazole, a commonly used drug againstamoebiasis, suggesting that oxovanadium(V) complexes derived from thiohydrazones may open a new dimensionin the therapy of amoebiasis.