Electronic effect on the molecular motion of aromatic amides: Combined studies using VT-NMR and quantum calculations

Sungsoo Kim, Jungyu Kim, Jieun Kim, Daeun Won, Suk Kyu Chang, Wansik Cha, Keunhong Jeong, Sangdoo Ahn, Kyungwon Kwak

Research output: Contribution to journalArticle

Abstract

Rotational barrier energy studies to date have focused on the amide bond of aromatic compounds from a kinetic perspective using quantum calculations and nuclear magnetic resonance (NMR). These studies provide valuable information, not only regarding the basic conformational properties of amide bonds but also the molecular gear system, which has recently gained interest. Thus, we investigate the precise motion of the amide bonds of two aromatic compounds using an experimental rotational barrier energy estimation by NMR experiments and a theoretical evaluation of the density functional theory calculation. The theoretical potential energy surface scan method combined with the quadratic synchronous transit 3 method and consideration of additional functional group rotation with optimization and frequency calculations support the results of the variable temperature1H NMR, with deviations of less than 1 kcal/mol. This detailed experimental and theoretical research strongly supports molecular gear motion in the aromatic amide system, and the difference in kinetic energy indicates that the electronic effect from the aromatic structure has a key role in conformational movements at different temperatures. Our study provides an enhanced basis for future amide structural dynamics research.

Original languageEnglish
Article number2294
JournalMolecules
Volume23
Issue number9
DOIs
Publication statusPublished - 2018 Sep 8

Keywords

  • Amide bond
  • Density functional theory
  • Kinetic
  • Nuclear magnetic resonance
  • Rotational barrier energy

ASJC Scopus subject areas

  • Analytical Chemistry
  • Chemistry (miscellaneous)
  • Molecular Medicine
  • Pharmaceutical Science
  • Drug Discovery
  • Physical and Theoretical Chemistry
  • Organic Chemistry

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