Mechanism of Hydrogen Bond Array Isomerization in Tetrahydroxycalix[4]arene and Tetrahydroxythiacalix[4]arene
| Authors | |
|---|---|
| Year of publication | 2008 |
| Type | Article in Periodical |
| Magazine / Source | Journal of Physical Chemistry A |
| MU Faculty or unit | |
| Citation | |
| Field | Physical chemistry and theoretical chemistry |
| Keywords | Calixarene DFT RIMP2 Hydrogen bond array mechanism |
| Description | Possible rearrangement mechanisms of hydrogen bond array formed at the lower rim of tetrahydroxycalix[4]arene and tetrahydroxythiacalix[4]arene were studied by means of the density functional theory and RI/MP2 modification of Moller Plesset perturbation theory. Influence of solvent to height of energy barriers was quantified using the COSMO model of implicit solvent (chloroform). Generally, two types of mechanisms were investigated. The first is represented by synchronous single step jump of all four hydroxyl protons. Pathways of the second mechanism include the rotation of one or more hydroxyl groups around the CArO bond. Theoretical results, in agreement with recently published experimental data (Lang, J. et al. J. Chem. Phys. 2005, 122, 044056), prefer jump mechanism for the methylene bridged calix[4]arene. Concerning the thiacalix[4]arene, results obtained by COSMO as well as RI-MP2 calculations show, that the rotational mechanism is very competitive and it could even be more favorable. |
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