Concomitant polymorphs of p-iso-propylcalix[4]arene

Abstract

Sublimation of p-iso-propylcalix[4]arene under reduced pressure results in the concomitant formation of two new polymorphs (forms II P and III P). Both forms consist of interdigitated dimers of calixarene molecules, as does the known form I P. Despite similar inclusion behaviour to that of p-tert-butylcalix[4]arene, p-iso-propylcalix[4]arene does not appear to favour the formation of a transiently porous material.