Vibrational analysis of p-tert-butyl-calix[4]arene conformers by ab initio calculations

Abstract

Band frequencies and intensities in the IR spectra of calix[4]arene have been calculated. Ab initio calculations at HF/6-311G (d, p) level gave vibrational frequencies and infrared intensities for four conformers: cone, partial cone, 1,2- and 1,3-alternate. The geometry optimization has been performed in the basis of C2 symmetry frame of p-tert-butyl-calix[4]arene as a calculation input because it contains no imaginary vibrational frequencies. Additionally the experimental IR spectra of the p-tert-butyl-calix[4]arene were measured and related to the theoretical geometric parameters and force constants. The bands characteristic for each conformation and its reference with respect to specially the OH stretching were defined. Finally we discuss the possibility of hydrogen bonding stability of conformers were discussed.

Keywords:

• Calixarenes
• Conformations
• Normal vibrations
• IR spectra