作者:Sebastian Schmidt-Schäffer、Lutz Grubert、Ulrich W. Grummt、Karin Buck、Werner Abraham
DOI:10.1002/ejoc.200500421
日期:2006.1
the end of the molecular thread and the number of oxygen atoms within the chain. By tuning the chain length it has also been achieved that both of the rotaxanes incorporating the diarylcycloheptatriene unit and the tropylium-containing rotaxanes adopt an unfolded structure in solution. The tetracationic ring resides exclusively on the second aryl station within the tropylium rotaxanes. Switching between
新型 [2] 轮烷含有四阳离子环双 (paraquat-4,4-亚联苯) 和哑铃形分子线,包含光敏二芳基环庚三烯站和光失活芳基站,产率近 30%分子线的两半耦合。每一半包含由四阳离子环识别的两个站之一。转换原理基于带有合适的离去基团(例如甲氧基取代基)的二芳基环庚三烯的光杂解作用。通过电化学氧化将轮烷转化为相关的含有二芳基托鎓单元的轮烷。所有轮烷的共构象均通过 1 H NMR 和 UV/Vis 光谱确定。已经表明,四阳离子环对两个不同站点的占用取决于这些站点的电子供体容量和站点之间的链单元。通过对分子线末端的终止基团和链内氧原子数进行微调,实现了二芳基环庚三烯站的所需优选占据。通过调整链长,还实现了结合二芳基环庚三烯单元的轮烷和含托鎓的轮烷在溶液中均采用未折叠结构。四阳离子环仅位于 tropylium 轮烷内的第二个芳基位置上。可以通过甲氧基取代的二芳基环庚三烯的光杂解作用来实现含环庚三烯