A study of conformational stability and vibrational assignments of 1-aminocyclopropanecarboxylic acid c-C3H4(NH2)-COOH

作者：Badawi Hassan M^*

来源：Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy , 2009, 73(4): 707-712.

DOI：10.1016/j.saa.2009.03.014

• Vibrational spectra and assignments
• Conformational equilibrium constant
• 1-Aminocyclopropanecarboxylic acid

The structural stability of 1-aminocyclopropanecarboxylic acid was investigated at DFT-BLYP, DFT-B3LYP and ab initio MP2 levels of theory with 6-311G** basis set. The molecule was predicted at the three levels of calculation to exist in cis-syn double left right arrow trans-syn conformational equilibrium. The equilibrium constants for the conformational interconversion were calculated and found to correspond to an equilibrium mixture of about 35% cis-syn and 65% trans-syn conformations at 298.15 K. The cis-trans rotational barrier and the NH2 syn-anti inversion barrier were estimated to be about 6 and 7 kcal/mol, respectively. The O-H rotational barrier was calculated to be of the order 12-14 kcal/mol. The vibrational frequencies of the two stable conformers of the acid were computed at the BLYP and the B3LYP levels of theory. Only vibrational assignments were provided for the low energy trans-syn conformer on the basis of normal coordinate analysis and experimental data. No clear evidence was found for the presence of the second high energy cis-syn structure in the spectra of the molecule.

• 出版日期2009-8-15
• 单位中国石油大学（北京）