Theoretical study of vibrational spectra of p-tert-butylcalix[4]crown-6-ether complexed with ethyl ammonium cation

Theoretical infrared (IR) absorption spectra were calculated for p-tert-butylcalix[4]crown-6-ether (1) in the cone conformer and its ethyl ammonium complex. The IR spectra were obtained by restricted Hartree–Fock (RHF) calculations with the 6-31G basis set. For the purpose of an absorption band assignment on the host molecule, guest molecule, and complexes thereof, we discussed a way to distinguish a specific molecule by comparing the calculated vibrational spectra. The theoretical result for the host molecule 1 and its ethyl ammonium complex were preliminarily compared with the experimental result, and found that the calculated result agrees well with the features of the experimental spectra.