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The cone conformation of 4 symmetry is shown by the Hartree-Fock method (3-21G basis) to be the predominant conformer of calix [4]arene; the compressed cone of 2 symmetry is the major conformer of calix [6] [7-9, 12, 13] and density functional [6-9, 14] methods, and only one work deals with investigation of calix [6]arenes by these methods [13]. None of these works dealing with calixarenes has reported on hydrogen bond energy calculations, although this energy is the key factor of conformational stability and conformational lability of calixarenes with free hydroxyl groups [12] and their reactivity [11].The stability of the hydrogen bond in calixarene was correlated with the reaction route involving this compound when dialkoxydihydroxycalix[4]arene was synthesized from monoalkoxytrihydroxycalix[4]arene [11] (Fig. 1). Similar alkylation and acylation reactions with intermediate phenoxide anions stabilized by the maximum number of stable hydrogen bonds were also reported for calixarenes having larger rings [11]. In his review [11] D. Rudkevich demonstrated in detail that intramolecular hydrogen bonds are as important as intermolecular hydrogen bonds for molecular void formation. Therefore further investigation of intramolecular hydrogen bonding in "guest-host" complexes (in particular, investigation of the energy parameters of hydrogen bonds) is of great importance in view of the influence of intramolecular hydrogen bonds on the route and rate of transformations involving cleavage and formation of covalent bonds and on the complexation ability of cavitands.I. I. Mechnikov Odessa National University; andrej_novikov@mail.ru, andrej_novikov@ukr.net.

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