Shape-Persistent Triptycene-Derived Pillar[6]arenes: Synthesis, Host-Guest Complexation, and Enantioselective Recognitions of Chiral Ammonium Salts

Construction of macrocyclic hosts with a novel structureand excellentproperty has emerged as an intriguing undertaking for the past fewyears. Here, we reported the synthesis of shape-persistent triptycene-derivedpillar[6]arene (TP[6]). The single crystal structureanalysis revealed that the macrocyclic molecule adopts a hexagonalstructure, featuring a helical and electron-rich cavity capable ofencapsulating electron-deficient guests. In order to obtain chiral TP[6] from an enantiomerically pure triptycene building block,an efficient resolution of chiral triptycene was successfully developedthrough introducing chiral auxiliaries into triptycene skeletons.The H-1 NMR and isothermal titration calorimetry investigationsdemonstrated that chiral TP[6] exhibited enantioselectivitytoward four pairs of chiral guests containing a trimethylamino group,implying a significant promising application in area of enantioselectiverecognition.