Cation complexation of quinocrown ethers in electrospray ionization mass spectrometry. A comparison with benzocrown ethers
作者:Akihiko Tsuda、Hiroshi Moriwaki、Takumi Oshima
DOI:10.1039/a808752k
日期:——
The alkali metal complexation of 15- to 18-membered ring quinocrown ethers Q15–18, 18- and 24-membered diquinocrown ethers DQ18,24, and 18-membered quinobenzocrown ether QB18 is compared with that of the corresponding benzocrown ethers B15–18 and dibenzo crown ethers DB18,24 in electrospray ionization mass spectrometry (ESI-MS). The quinocrown ethers exhibit lower cation affinity than the benzocrown ethers, although the two crown series essentially show the same ion selectivity except 18-membered DQ18 which preferentially binds Na+. The reduced binding ability of the quinocrowns is interpreted in terms of the deformation of the crown rings by the steric repulsion with the quinone carbonyls as well as the electron withdrawing ability of the fused quinone.
在电喷雾离子化质谱(ESI-MS)中,将 15 至 18 元环喹冠醚 Q15-18、18 元环和 24 元环二喹冠醚 DQ18,24 以及 18 元环喹苯并冠醚 QB18 的碱金属络合与相应的苯并冠醚 B15-18 和二苯并冠醚 DB18,24 的碱金属络合进行了比较。与苯并冠醚相比,醌冠醚的阳离子亲和力较低,但除了 18 元 DQ18 更倾向于结合 Na+ 外,这两种冠醚系列基本上表现出相同的离子选择性。醌冠醚结合能力降低的原因是冠环在与醌羰基的立体排斥作用下发生了形变,以及融合醌的电子撤回能力。