Lee Seoung Ho, Kim Jong Yeol, Ko Jaejung, Lee Ji Yeon, Kim Jong Seung
Department of Chemistry, Konyang University, Nonsan 320-711, Korea.
J Org Chem. 2004 Apr 16;69(8):2902-5. doi: 10.1021/jo049954o.
A series of 1,3-alternate chromogenic azo-coupled calix[4]biscrowns in which the crown size varied with crown-5 and crown-6 have been synthesized. From the results of UV/vis band shift upon metal ion complexation, metal ions were entrapped only by the upper crown loop, causing the hypsochromic shift on the UV/vis spectra. Calix[4]bis(crown-5)(crown-6) revealed K(+) ion selectivity while calix[4]bis(crown-6)(crown-6) showed Cs(+) ion selectivity caused by a size complementarity between hosts and guest ions. From the UV band shift of 4 in which the NO(2) group is replaced by the NH(2) group, we observed bathochromic shift upon the metal ion addition, indicating that the metal ion is encapsulated in the lower crown ring because of strengthened pi-cation interaction by introducing the electron-donating NH(2) unit regardless of the steric hindrance between two azo-phenyl groups adjacent to the crown ring.
已经合成了一系列1,3-交替的发色偶氮偶联杯[4]双冠醚，其中冠醚大小随冠-5和冠-6而变化。根据金属离子络合时紫外/可见光谱带的移动结果，金属离子仅被上部冠醚环捕获，导致紫外/可见光谱发生紫移。杯[4]双（冠-5）（冠-6）表现出对K(+)离子的选择性，而杯[4]双（冠-6）（冠-6）由于主体和客体离子之间的尺寸互补性而表现出对Cs(+)离子的选择性。从4中NO(2)基团被NH(2)基团取代后的紫外光谱带移动情况来看，我们观察到加入金属离子后发生红移，这表明由于引入供电子的NH(2)单元增强了π-阳离子相互作用，金属离子被封装在下部冠醚环中，而不管与冠醚环相邻的两个偶氮苯基之间的空间位阻如何。
