Conformation effects on the electronic structures of beta-alanine.
Ten low-lying conformers of beta-alanine have been studied by the hybrid density functional B3LYP/aug-cc-pVDZ method. Energetic extrapolation calculations at the MP3 and MP4(SDQ) levels of theory and the theoretical photoelectron spectra simulated with the electron propagation theory demonstrate that there are at least three gauche conformers (G1, G2, and G3) in gas-phase experiments. The calculated ionization potentials are in good agreement with the experimental data available in the literature. Natural bond orbital and atoms-in-molecules analyses exhibit a remarkable influence on the molecular electronic structures by the strong intramolecular hydrogen bonding O-H...N in the neutral conformer G2. Remarkable internal rotations of the COOH group are found in the cationic G1+ and G3+ with respect to the neutral conformers. A distonic [NH3+-(CH2)2-COO*] radical can be formed through the spontaneous intramolecular proton transfer in G2+. A novel intramolecular hydrogen bonding, C-H...O, is found in the anti A1+ cation.
Tian
Shan Xi
SX
Hefei National Laboratory for Physical Sciences at Microscale, Laboratory of Bond Selective Chemistry, Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
D003198:Computer Simulation; D004583:Electrons; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D011789:Quantum Theory; D015091:beta-Alanine / Q000737:chemistry*
D015091:beta-Alanine