Nine-Coordinate Lanthanide Podates with Predetermined Structural and Electronic Properties: Facial Organization of Unsymmetrical Tridentate Binding Units by a Protonated Covalent Tripod
作者:Fabien Renaud、Claude Piguet、Gérald Bernardinelli、Jean-Claude G. Bünzli、Gérard Hopfgartner
DOI:10.1021/ja990898w
日期:1999.10.1
producing a clipped conformation preorganized for the complexation of lanthanide metal ions. Reactions of L10 and [L10+H]+ with Ln(ClO4)3 (Ln = La−Lu) in acetonitrile provide stable nine-coordinate podates [Ln(L10)]3+ and [Ln(L10+H)]4+. Thermodynamic investigations indicate that the increased electrostatic repulsion associated with the complexation of the protonated podand is compensated by preorganization
三个不对称的三齿吡啶-2,6-二甲酰胺结合单元已连接到三(2-(N-甲基)氨基乙基)胺三脚架上,以提供作为四种构象异构体在溶液中的统计混合物存在的 podand L10。在水性酸性介质中,三脚架的质子化顶端氮原子 (pKa([L10+H]+) = 4.66(2)) 采用内构象,与三脚架的氧原子形成双和三叉氢键相容。近端羧酰胺基团,从而产生为镧系金属离子络合而预先组织的剪裁构象。L10 和 [L10+H]+ 与 Ln(ClO4)3 (Ln = La−Lu) 在乙腈中的反应提供了稳定的九配位足类 [Ln(L10)]3+ 和 [Ln(L10+H)]4+ . 热力学研究表明,与质子化豆荚的络合相关的静电排斥增加被预组织补偿,导致对最终豆荚稳定性的影响很小。溶液中的结构表征使用...