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Ab initio and density functional studies of cooperative hydrogen bonding in calix[4]-and calix[6]arenes

“…Also, note the following: the results of RHF/6-31G(d) and RHF/6-31G calculations of the structural and energy parameters of hydrogen bonding in compound I are quite comparable with one another and with experimental data (see also [6,9]); the experimental values of the energy parameters of hydrogen bonding in calixarenes are yet unknown; RHF/6-31G(d), RHF/6-31G(d,p), 2/6-31G(d), and 2/6-31G(d,p) studies of compound III still present great difficulty. As can be seen from the data of Tables 1, 2, and 3, calculations on calix [4]arenes using 3-21G, 3-21G(d,p), 6-31G, and 6-31G(d) bases, as well as calculations on calix [6]arenes using STO-2G, 3-21G, and 6-31G bases, give reliable structural data because the results of these calculations are in reasonable agreement with experimental data (see also [13]). …”

“…Our RHF/STO-2G [13] and RHF/3-21G ab initio calculations predict that the 4 cone is the most stable conformer of calix [4]arene (Fig. 2 ) and that the 2 compressed cone is the most stable conformer of calix [6]arene (Fig.…”

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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.

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“…These compounds along with crown ethers are useful in modeling molecular recognition processes and in studies of molecular and ion transfer across cell membranes [10]. A few works are devoted to studies of calix [4]arenes and thiacalix [4]arenes by ab initio [7-9, 12, 13] and density functional [6][7][8][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].…”

Interaction of para-tert-butylcalix[6]arene molecules in Langmuir films with cadmium ions and their effects on molecular conformation and surface potential

“…The Calix6 molecule was assumed to adopt the cone conformation, which is considered the most stable for calixarene derivatives with six rings. 31,39,40 The difference in the experimentally observed value (135 Å 2 ) may be ascribed to two factors: (i) the theoretical calculations were performed using zero Kelvin temperature, under vacuum, with no water molecules that could H-bond to Calix6 and (ii) repulsion between Calix6 molecules, which is not taken into account in the theoretical modeling. A similar reasoning was adopted by Torrent-Burgués et al 10 for the derivative p-tertbutylcalix [7]arene ethyl ester.…”