Ab initio studies of the conformers and conformational distribution of gas-phase N,N -dimethylaminopropanol

Abstract

Systematic and extensive conformational search has been performed to characterize the gas-phase N,N-dimethylaminopropanol structures. A total of 91 unique trail structures were generated by allowing for all the single-bond rotamers. All the trial structures were initially optimized at the AM1 level, and the resulting structures were optimized at the B3LYP/6-311G* level of theory and then subjected to further optimization at the B3LYP/6-311++G**. A total of 36 conformers are found and their zero-point vibrational enegies, rotational constants, and dipole moments are determined. Vertical ionization energies of 11 low-lying conformers predicted with the electron propagator theory are in good agreement with the experimental data. The two most stable conformers display intramolecular H bonds (HBs): OH···N. These HBs influence on the molecular electronic structures is exhibited by natural bond orbital analyses. Combined with statistical mechanics principles, conformational distributions at various temperatures are computed and the temperature dependence of photoelectron spectra is interpreted. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010