### Abstract

The aim of this work was to present a comprehensive vibrational spectroscopic study of 25,26,27,28-tetrahydroxycalix[4]arene. For this purpose, quantum chemical calculations were carried out at the ab initio HF/4-31G* level, as a consequence of the great size of the molecule. In the frame of these calculations, the symmetry of the molecule was investigated. Trying C_{4V}, C_{2V}, and C_{s} symmetries as input, the geometry optimization, however, pointed to the C_{2} configuration. In the latter case, all the calculated vibrational frequencies were greater than zero, and therefore the equilibrium geometry could be identified. Medium and far infrared as well as Raman spectra of the compound were measured. On the basis of the calculated force constants and geometric parameters, normal coordinate analysis was applied for the interpretation of the experimental vibrational spectra. Problems arose with the choice of the internal coordinates of the molecule, which are important from the point of view of the internal macrocycle ("lower rim") of the molecule. On the basis of the theory of redundant coordinates, a program was written for choosing the coordinates of this 16-membered cycle. Full interpretation of the vibrational fundamentals of the compound is presented. Several force constant matrix elements have surprisingly high values. As a result of the normal coordinate analysis, the relative rigidity of the lower rim was concluded. Ab initio calculations and assignment of the vibrational spectra of 25,26,27,28-tetrahydroxycalix[4]arene based on the calculations are presented.

Original language | English |
---|---|

Pages (from-to) | 451-459 |

Number of pages | 9 |

Journal | Supramolecular Chemistry |

Volume | 14 |

Issue number | 5 |

DOIs | |

Publication status | Published - Oct 2002 |

### Fingerprint

### Keywords

- Ab initio
- Calix[4]arene
- Geometry
- Normal coordinate analysis
- Vibrational spectra

### ASJC Scopus subject areas

- Chemistry(all)

### Cite this

*Supramolecular Chemistry*,

*14*(5), 451-459. https://doi.org/10.1080/10610270212491

**Ab initio equilibrium geometry and vibrational spectroscopic study of 25,26,27,28-tetrahydroxycalix[4]arene.** / Billes, F.; Mohammed-Ziegler, Ildikó.

Research output: Contribution to journal › Article

*Supramolecular Chemistry*, vol. 14, no. 5, pp. 451-459. https://doi.org/10.1080/10610270212491

}

TY - JOUR

T1 - Ab initio equilibrium geometry and vibrational spectroscopic study of 25,26,27,28-tetrahydroxycalix[4]arene

AU - Billes, F.

AU - Mohammed-Ziegler, Ildikó

PY - 2002/10

Y1 - 2002/10

N2 - The aim of this work was to present a comprehensive vibrational spectroscopic study of 25,26,27,28-tetrahydroxycalix[4]arene. For this purpose, quantum chemical calculations were carried out at the ab initio HF/4-31G* level, as a consequence of the great size of the molecule. In the frame of these calculations, the symmetry of the molecule was investigated. Trying C4V, C2V, and Cs symmetries as input, the geometry optimization, however, pointed to the C2 configuration. In the latter case, all the calculated vibrational frequencies were greater than zero, and therefore the equilibrium geometry could be identified. Medium and far infrared as well as Raman spectra of the compound were measured. On the basis of the calculated force constants and geometric parameters, normal coordinate analysis was applied for the interpretation of the experimental vibrational spectra. Problems arose with the choice of the internal coordinates of the molecule, which are important from the point of view of the internal macrocycle ("lower rim") of the molecule. On the basis of the theory of redundant coordinates, a program was written for choosing the coordinates of this 16-membered cycle. Full interpretation of the vibrational fundamentals of the compound is presented. Several force constant matrix elements have surprisingly high values. As a result of the normal coordinate analysis, the relative rigidity of the lower rim was concluded. Ab initio calculations and assignment of the vibrational spectra of 25,26,27,28-tetrahydroxycalix[4]arene based on the calculations are presented.

AB - The aim of this work was to present a comprehensive vibrational spectroscopic study of 25,26,27,28-tetrahydroxycalix[4]arene. For this purpose, quantum chemical calculations were carried out at the ab initio HF/4-31G* level, as a consequence of the great size of the molecule. In the frame of these calculations, the symmetry of the molecule was investigated. Trying C4V, C2V, and Cs symmetries as input, the geometry optimization, however, pointed to the C2 configuration. In the latter case, all the calculated vibrational frequencies were greater than zero, and therefore the equilibrium geometry could be identified. Medium and far infrared as well as Raman spectra of the compound were measured. On the basis of the calculated force constants and geometric parameters, normal coordinate analysis was applied for the interpretation of the experimental vibrational spectra. Problems arose with the choice of the internal coordinates of the molecule, which are important from the point of view of the internal macrocycle ("lower rim") of the molecule. On the basis of the theory of redundant coordinates, a program was written for choosing the coordinates of this 16-membered cycle. Full interpretation of the vibrational fundamentals of the compound is presented. Several force constant matrix elements have surprisingly high values. As a result of the normal coordinate analysis, the relative rigidity of the lower rim was concluded. Ab initio calculations and assignment of the vibrational spectra of 25,26,27,28-tetrahydroxycalix[4]arene based on the calculations are presented.

KW - Ab initio

KW - Calix[4]arene

KW - Geometry

KW - Normal coordinate analysis

KW - Vibrational spectra

UR - http://www.scopus.com/inward/record.url?scp=0036799891&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0036799891&partnerID=8YFLogxK

U2 - 10.1080/10610270212491

DO - 10.1080/10610270212491

M3 - Article

VL - 14

SP - 451

EP - 459

JO - Supramolecular Chemistry

JF - Supramolecular Chemistry

SN - 1061-0278

IS - 5

ER -