Department of Chemistry, University of Texas, 78712, Austin, TX.
J Am Soc Mass Spectrom. 1992 Jul;3(5):543-8. doi: 10.1016/1044-0305(92)85031-E.
Ladders of relative alkali ion affinities of crown ethers and acyclic analogs were constructed by using the kinetic method. The adducts consisting of two different ethers bound by an alkali metal ion, (M1 + Cat + M2)(+), were formed by using fast atom bombardment ionization to desorb the crown ethers and alkali metal ions, then collisionally activated to induce dissociation to (M1 + Cat)(+) and (M2 + Cat)(+) ions. Based on the relative abundances of the cationized ethers formed, orders of relative alkali ion affinities were assigned. The crown ethers showed higher affinities for specific sizes of metal ions, and this was attributed in part to the optimal spatial fit concept. Size selectivities were more pronounced for the smaller alkali metal ions such as Li(+), Na(+), and K(+) than the larger ions such as Cs(+) and Rb(+). In general, the cyclic ethers exhibited greater alkali metal ion affinities than the corresponding acyclic analogs, although these effects were less dramatic as the size of the alkali metal ion increased.
采用动力学方法构建了冠醚和非环类似物的相对碱金属离子亲和度阶梯。通过使用快原子轰击电离解吸冠醚和碱金属离子，形成由两种不同醚通过碱金属离子结合而成的加合物 (M1 + Cat + M2)(+)，然后通过碰撞激活诱导其解离为 (M1 + Cat)(+) 和 (M2 + Cat)(+) 离子。基于形成的阳离子化醚的相对丰度，分配了相对碱金属离子亲和力的顺序。冠醚对特定大小的金属离子表现出更高的亲和力，这部分归因于最佳空间适配概念。较小的碱金属离子（如 Li(+)、Na(+) 和 K(+)）的尺寸选择性比较大的离子（如 Cs(+) 和 Rb(+)）更明显。一般来说，环状醚表现出比相应的非环类似物更高的碱金属离子亲和力，尽管随着碱金属离子尺寸的增加，这些效应不那么显著。
