From Tweezers to Cyclophanes

As a compromise, host 6.66 was designed. This species uses a napthyl spacer and incorporates a hydrogen-bond accepting pyridyl moiety at the core of its bonding pocket. One of the hexadiyne bridges has also been replaced by a shorter p-xylyl spacer, which results in additional edge-to-face Jt-Jt interactions. The association constant of this host for p-nitrophenol is much larger  

6 X 10 M in CD2CI2 solution. Intracavity complexation is strongly suggested by unusual H 

---