Experimental and theoretical evaluation on the conformational behavior of L-aspartic acid dimethyl ester and its N-acetylated derivative

Autor(es)

Braga, Carolyne B. ^[1] ; Ducati, Lucas C. ^[2] ; Rittner, Roberto ^[1]

Afiliação do(s) autor(es)

^[1] Univ Estadual Campinas, Phys Organ Chem Lab, Inst Chem, BR-13083970 Campinas, SP - Brazil

^[2] Univ Sao Paulo, Inst Chem, BR-05508900 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: RSC ADVANCES; v. 5, n. 23, p. 18013-18024, 2015.
• Citações Web of Science: 6

Resumo

In this work the conformational preferences of L-aspartic acid dimethyl ester (AspOMe) and its N-acetylated derivative (AcAspOMe) were evaluated through spectroscopic data and theoretical calculations. Unlike amino acids, their corresponding amino ester derivatives do not exhibit a zwitterionic structure and are soluble in most organic solvents, enabling their studies in these media. Thus, the conformers of AspOMe and AcAspOMe were theoretically determined both in isolated phase and in solution (IEF-PCM model) at the omega B97X-D/aug-cc-pVTZ level. A joint analysis of the experimental and theoretical (3)J(HH) coupling constants in several aprotic solvents allowed assigning the most stable conformers, showing excellent agreement between these approaches. Also, IR spectroscopy allowed us to obtain quantitative data on AcAspOMe conformer populations in different solvents. Natural bond orbital (NBO) analysis indicated that both steric and hyperconjugative contributions count in determining the relative conformer stabilities of these compounds. Intramolecular hydrogen bonding, characterized by Quantum Theory of Atoms in Molecules (QTAIM) and Non-Covalent Interactions (NCI) methodologies, represents only a secondary factor to drive the stabilities of AspOMe and AcAspOMe conformers. (AU)

• Processo FAPESP: 12/18567-4 - Investigação conformacional e das interações intramoleculares de derivados de aminoácidos utilizando as espectroscopias de RMN e IV e cálculos teóricos
• Beneficiário: Carolyne Brustolin Braga
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 12/03933-5 - Equilíbrios conformacionais e interações intramoleculares em uma série de aminoácidos: abordagem teórica e experimental
• Beneficiário: Roberto Rittner Neto
• Modalidade de apoio: Auxílio à Pesquisa - Regular