Synthesis of p-tert-butylthiacalix[4]arene and its inclusion property

A practical method for the synthesis of p-tert-butylthiacalix[4]arene (TC4A), in which the methylene bridges of p-tert-butyl-calix[4]arene (C4A) are replaced by epithio groups, is presented by heating a mixture of p-tert-butylphenol, elemental sulfur S-8, and NaOH as a base catalyst in tetraethylene glycol dimethyl ether. The inclusion behavior of TC4A for a wide range of solvent molecules is examined by recrystallization, showing preference for the guests depending upon the size and/or the substituent of the guests. The X-ray structure of a 1:2 host-guest complex of TC4A with 1,2-dichloroethane reveals that one guest molecule is included in the cavity of TC4A, while the other is included in the crystal lattice to form a clathrate-type complex. It is shown that the inclusion in the cavity is attained by a cooperative deformation of both the host and the guest. (C) 2000 Elsevier Science Ltd. All rights reserved.