Polymorphism and pseudopolymorphism in calixarenes: acetonitrileclathrates of p-But-calix[n]arenes (n = 6 and 8)

Abstract

Here we present four new structural determinations of p-Bu^t-calixarene acetonitrile clathrates, namely p-Bu^t-calix[6]arene·1.5MeCN (1), p-Bu^t-calix[6]arene·2MeCN (2), p-Bu^t-calix[8]arene·4MeCN (3) and p-Bu^t-calix[8]arene·2MeCN (4), and utilise the Cambridge Structural Database to highlight the extent of polymorphism and pseudopolymorphism within the solvent clathrate structures of these key compounds. Compounds 1 and 2 are the first examples of polymorphism and pseudopolymorphism in p-Bu^t-calix[6]arene solvent clathrates, the former phenomenon having been previously seen in p-Bu^t-calix[4]arene toluene clathrates and the latter in p-Bu^t-calix[8]arene pyridine clathrates, while compounds 3 and 4 themselves exhibit pseudopolymorphism.