DFT conformational study of the monomethoxycalix[5]arene

Abstract

In this study, we have performed DFT calculations to investigate the conformational characteristics and the hydrogen bonds of the monomethyl ether of p-tert-butylcalix[5]arene (1: 5,11,17,23,29-Penta-tert-butyl-31-methoxy-32,33, 34,35-tetrahydroxycalix[5]arene). The structures of different conformers of 1 were optimized by using B3LYP/6-31+G(d,p) method. The relative stability of the various conformers of 1 is in the following order: 2,3-alternate (most stable) > 1-partial-cone ∼ 1,2-alternate > cone > 2-partial-cone > 3-partial-cone ∼ 2,4-alternate ∼ 1,3-alternate. The primary factor affecting the relative stabilities of the various conformers of the monomethoxy-t-butylcalix[5]arene (1) are the number of the intramolecular hydrogen bonds.