Figure 4
(a) Intramolecular hydrogen bond distances of the most likely conformer of MPC calculated at a dielectric constant of 4.20. Intramolecular hydrogen bonds, HB1–HB11, are indicated by the dashed lines. The bond lengths at a dielectric constant of 2.07 are given in parentheses. The four hydrogen bonds that show a remarkable change in length due to the difference in dielectric constant are marked in red. The table shows the optimized bond lengths in Å calculated at the dielectric constant of 4.20 with the Petersson-Frisch dispersion model (pfd)40, the D3 version of Grimme’s dispersion (gd3)41, and without dispersion correction (–). (b) Vibrational modes given as ν1–ν5 in the right panel in Fig. 3b (δas: asymmetric bending in plane or rocking, τ: torsion). The frequency of each mode is the result calculated with a dielectric constant of 4.20 using the pfd model for dispersion correction. Intramolecular hydrogen bonds are indicated by the dashed lines. The blue arrows indicate the atomic displacement vectors. Mainly moving parts are marked with red circles. The stretching vibration of an intramolecular hydrogen bond is indicated by a red arrow along with the name of hydrogen bond.
