Molecular properties investigation of a substituted aromatic mannich base: dynamic and static models

An analysis of the hydrogen bridge of a Mannich base-type compound [3,5,6-trimethyl-2(N,N-dimethylaminomethyl)phenol, TMM] was performed according to the Car-Parrinello molecular dynamics (CPMD) scheme. A classical treatment of nuclei coupled with a first-principle potential energy surface was obtained from molecular dynamics simulation. Dipole moment values were collected during CPMD trajectory acquisition and subsequently used for the data analysis. The vibrational features and the intramolecular hydrogen-bond properties in the gas phase and solid state of the TMM compound were analyzed on the basis of widely used approaches: Fourier transformation of the autocorrelation function of both the atomic velocities and dipole moments. In addition, the time evolution of the structural parameters related to the hydrogen bond was carried out. The optimally localized Wannier functions served to describe the electronic structure of the Mannich base studied. The second part of the TMM compound study was performed in vacuo on the basis of density functional theory and second-order Møller-Plesset perturbation theory. The potential energy functions were used to solve the 1-D vibrational Schroedinger equation for the proton motion. This enabled a prediction of the anharmonic vibrational levels of the intramolecular hydrogen bond. The description of the electron density topology of the TMM molecule was carried out using the atoms in molecules theoretical framework. The computational results were further compared with the infrared spectra in the solid state.