Coordination Behavior toward Copper(II) and Zinc(II) Ions of Three Ligands Joining 3-Hydroxy-2-pyridinone and Polyaza Fragments
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- 作者：Gianluca Ambrosi ; Mauro Formica ; Vieri Fusi ; Luca Giorgi ; Annalisa Guerri ; Simone Lucarini ; Mauro Micheloni ; Paola Paoli ; Patrizia Rossi ; and Giovanni Zappia
- 刊名：Inorganic Chemistry
- 出版年：2005
- 出版时间：May 2, 2005
- 年：2005
- 卷：44
- 期：9
- 页码：3249 - 3260
- 全文大小：232K
- 年卷期：v.44,no.9(May 2, 2005)
- ISSN：1520-510X
文摘
The synthesis and characterization of new polydentate ligand 2-(N),2'-(N')-bis[2-(3-hydroxy-2-oxo-2H-pyridin-1-yl)acetamido]-1(N'),2(N),2'(N')-trimethyl-2,2'-diaminodiethylamine (L3) is reported. The coordination properties of L3and of two analogous macrocyclic ligands (L1 and L2) toward Cu(II) and Zn(II) metal ions are reported. All threeligands show the 3-hydroxy-2(1H)-pyridinone (HPO) groups attached as sidearms to a polyaza fragment, which isa macrocyclic framework in the case of L1 and L2 while it is an open chain in the case of L3. The role of thepolyaza fragments in preorganizing the two sidearms was investigated. The basicity of L3 and the binding propertiesof L1-L3 were determined by means of potentiometric measurements in aqueous solution (298.1 ± 0.1 K, I =0.15 mol dm-3). UV-vis spectra as well 1H and 13C NMR experiments were used to understand the role of theHPO and of the polyaza fragments in the stabilization of the cations. While L1 forms stable mono- and dinuclearcomplexes, L2 and L3 can form only mononuclear species with each of the metal ions investigated. In the mainmononuclear species of L2 and L3, the two HPO moieties stabilize the M(II) in a square planar geometry due tothe two oxygen atoms of each HPO. The coordination sphere of the metal is completed by adding a secondaryligand such as water molecules in the case of Cu(II) systems or OH- in the Zn(II) systems. These results areconfirmed by the crystal structures of the [CuH-1L2]+ and [CuH-1L3]+ species reported herein. Two conformationsof L1 can be hypothesized in the formation of the dinuclear species, as suggested by NMR experiments on the[ZnH-2L1] species, which shows two conformers slowly interchanging on the NMR time scale, one of which wasfound to be more insoluble.