Ambrosi Gianluca, Formica Mauro, Fusi Vieri, Giorgi Luca, Guerri Annalisa, Lucarini Simone, Micheloni Mauro, Paoli Paola, Rossi Patrizia, Zappia Giovanni
Institute of Chemical Sciences and Institute of Pharmaceutical Chemistry, University of Urbino, P.za Rinascimento 6, I-61029 Urbino, Italy.
Inorg Chem. 2005 May 2;44(9):3249-60. doi: 10.1021/ic0484607.
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 L3 and of two analogous macrocyclic ligands (L1 and L2) toward Cu(II) and Zn(II) metal ions are reported. All three ligands show the 3-hydroxy-2(1H)-pyridinone (HPO) groups attached as sidearms to a polyaza fragment, which is a macrocyclic framework in the case of L1 and L2 while it is an open chain in the case of L3. The role of the polyaza fragments in preorganizing the two sidearms was investigated. The basicity of L3 and the binding properties of 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 the HPO and of the polyaza fragments in the stabilization of the cations. While L1 forms stable mono- and dinuclear complexes, L2 and L3 can form only mononuclear species with each of the metal ions investigated. In the main mononuclear species of L2 and L3, the two HPO moieties stabilize the M(II) in a square planar geometry due to the two oxygen atoms of each HPO. The coordination sphere of the metal is completed by adding a secondary ligand such as water molecules in the case of Cu(II) systems or OH- in the Zn(II) systems. These results are confirmed by the crystal structures of the [CuH(-1)L2]+ and [CuH(-1)L3]+ species reported herein. Two conformations of L1 can be hypothesized in the formation of the dinuclear species, as suggested by NMR experiments on the [ZnH(-2)L1] species, which shows two conformers slowly interchanging on the NMR time scale, one of which was found to be more insoluble.
报道了新型多齿配体2-(N)，2'-(N')-双[2-(3-羟基-2-氧代-2H-吡啶-1-基)乙酰胺基]-1(N')，2(N)，2'(N')-三甲基-2，2'-二氨基二乙胺(L3)的合成与表征。报道了L3以及两种类似大环配体(L1和L2)对Cu(II)和Zn(II)金属离子的配位性质。所有三种配体都显示出3-羟基-2(1H)-吡啶酮(HPO)基团作为侧链连接到多氮杂片段上，在L1和L2的情况下，该片段是大环骨架，而在L3的情况下是开链。研究了多氮杂片段在预组织两个侧链中的作用。通过在水溶液(298.1±0.1 K，I = 0.15 mol dm(-3))中的电位测量确定了L3的碱度以及L1-L3的结合性质。紫外可见光谱以及1H和13C NMR实验用于了解HPO和多氮杂片段在阳离子稳定中的作用。虽然L1形成稳定的单核和双核配合物，但L2和L3与所研究的每种金属离子只能形成单核物种。在L2和L3主要的单核物种中，由于每个HPO的两个氧原子，两个HPO部分以平面正方形几何结构稳定M(II)。在Cu(II)体系中，通过添加二级配体如水分子或在Zn(II)体系中添加OH-来完成金属的配位球。本文报道的[CuH(-1)L₂]+和[CuH(-1)L₃]+物种的晶体结构证实了这些结果。如对[ZnH(-2)L1]物种的NMR实验所表明的，在形成双核物种时可以假设L1有两种构象，该物种显示出两种构象在NMR时间尺度上缓慢互换，其中一种被发现更难溶解。
