Intramolecular Hydrogen Bonding, Gauche Interactions, and Thermodynamic Functions of 1,2-Ethanediamine, 1,2-Ethanediol, and 2-Aminoethanol:  A Global Conformational Analysis

Abstract

The global conformational potentials of 1,2-ethanediol, 1,2-ethanediamine, and 2-aminoethanol (X-CH 2 -CH 2 -Y; X, Y ) OH or NH 2 ) were obtained at the MP2/6-311+G(2d,p) level by scanning through the dihedral angles of the two functional groups and the carbon-carbon bond with the remaining nuclear coordinates being energy-minimized. It was found that the potentials could be represented by the direct-bond potentials between the adjacent molecular fragments and by the through-space electrostatic potentials between the vicinal and geminal fragments. Here, the through-direct-bond potentials are represented by the conventional three Fourier terms of the internal rotation angles, and the through-space potentials, which include the intramolecular hydrogen bonding between X and Y, are represented by the general functional forms of the electric dipoledipole, dipole-quadrupole, and quadrupole-quadrupole interaction terms. The fitted electrostatic interaction strengths between the X and Y fragments are in good agreement with the predictions of the theoretical molecular fragment dipole and quadrupole moments calculated by the Hirshfeld charge population analysis. Under the present energy decomposition scheme, the intrinsic gauche interactions, which are free of the contribution of the intramolecular H-bonding, could be obtained and correlated with the group electronegativities of X and Y. The potentials were also calculated by the MM3 molecular mechanics method and compared with the present results. With the global conformation potentials, the thermodynamic functions of the molecules and also their individual conformers are calculated and compared with the gas-phase experimental thermodynamic data in the literature.

Structure–Activity Relationships of Cyanoquinolines with Corrector–Potentiator Activity in ΔF508 Cystic Fibrosis Transmembrane Conductance Regulator Protein

“…18 Since 5 is also active, however, a 26 -like conformation would need to be energetically accessible. Altering the conformation of 5 such that the isoquinoline and methoxyphenyl groups are in the same relative orientation as in 26 (and allowing the rest of the molecule to relax; see Supporting Information for details) is predicted to be accompanied by an increase in energy of approximately 4 kcal/mol (likely the result of not only disrupting π-stacking, but also disrupting the gauche conformation of the N–C–C–N substructure, which is preferred on both steric and orbital-based grounds over less-staggered conformations; 19 note that this distorted conformation is predicted to be approximately 8 kcal/mol above the lowest energy conformation of 5 in water). Thus, 5 could adopt the shape of 26 if this energy penalty is not enough to cause dissociation or is counterbalanced by favorable interactions with a binding site cavity complementary to 26 .…”

Structural and vibrational characterisation of 3-amino-1-propanol a concerted SCF-MO ab initio, Raman and infrared (matrix isolation and liquid phase) spectroscopy study

“….e. nearly twice that associated with the intramolecular process in the most stable conformer [1,9]), leads necessarily to the break of the intramolecular OH N hydrogen bond of the two most stable forms found in the vapour phase. Indeed, no spectroscopic evidence of the presence of these two forms in liquid 2AE could be found [1].…”

Pairwise interaction enthalpies of enantiomers of β‐amino alcohols in DMSO + H2O mixtures at 298.15 K

“…It has been also confirmed by Mulla that aminopropanol can form intramolecular hydrogen bond with a six‐membered ring structure. In addition, according to Chang and Katagiri, it has been certainly inferred that 2‐amino‐1‐alcohol forms intramolecular hydrogen bond with a five‐membered ring structure, which is very stable (Scheme ).…”