Ab Initio Study of the Conformations of Tetramethoxycalix[4]arenes

Abstract

In this study we have performed ab initio computer simulations to investigate the conformational characteristics of the tetramethoxycalix[4] arenes (1 and 2). The structures of four types (cone, partial cone, 1,2-alternate, and 1,3-alternate) of conformers for each compound have been optimized using ab initio RHF/6-31G and 6-31G** methods. General trends in relative stabilities of tetramethyl ether derivatives of calix[4] arene 1 and p-tert-butylcalix[4]arene 2 are similar and decrease in following order: partial cone (most stable) > cone > 1,3-alternate > 1,2-alternate. The calculated results of the most stable conformation of partial cone structure agree with the reported NMR experimental observations.