RAMAN SPECTRA OF TETRAOXA[8]CIRCULENES - <i>para</i>-DINAPHTHYLENODIPHENYLENOTETRAFURAN AND ITS TETRAALKYL DERIVATIVES (DFT STUDY AND EXPERIMENT)
The equilibrium molecular geometry, harmonic vibrational frequencies, and Raman band intensities are calculated by the density functional theory B3LYP method with the 6-31G(d) basis set for tetraoxa[8]circulenes - para-dinaphthylenodiphenylenotetrafuran (p-2B2N) and para-dinaphthyleno-2,3,10,11-tetraethyldiphenyleno tetrafuran (p-2B2N4R, R = C2H5) whose molecules belong to D2h and D2 point symmetry groups. Based on quantum chemical calculations of the frequencies and normal vibration modes of these molecules, all the bands in the measured Raman spectrum of tetraoxa[8]circulene para-dinaphthyleno-2,3,10,11-tetraundecyldiphenylenotetrafuran (p-2B2N4R, R = n-C11H23) have been assigned. Comparison of the calculated vibrational spectra with those from the experiment makes it possible to assign reliably all observed bands in the Raman spectrum. The results of quantum-chemical calculations are in a good agreement with the experimental data.