A Comprehensive Picture of the Structures, Energies, and Bonding in the Alanine Dimers. Issue 23 (22nd October 2021)

• Record Type: Journal Article
• Authors: David, Jorge; Gómez, Sara; Guerra, Doris; Guerra, Dario; Restrepo, Albeiro
• Is Part Of: Chemphyschem. Volume 22:Issue 23(2021)
• Page Start: 2401
• Page End: 2412
• Publication Date: 2021-10-22
• Subjects: Alanine dimers -- NBO -- NCI -- QTAIM -- Stochastic search of potential energy surfaces; Chemistry, Physical and theoretical -- Periodicals; 541.05
• DOI: 10.1002/cphc.202100585
• Languages: English
• ISSNs: 1439-4235

Abstract

Abstract: High level quantum mechanical computations and extensive stochastic searches of the potential energy surfaces of the Alanine dimers uncover rich and complex structural and interaction landscapes. A total of 416 strongly bound (up 13.4 kcal mol −1 binding energies at the DLPNO‐CCSD(T)/6–311++G( d, p ) level corrected by the basis set superposition error and by the zero point vibrational energies over B3LYP‐D3 geometries), close energy equilibrium structures were located, bonded via 32 specific types of intermolecular contacts including Y⋅⋅⋅H−X primary and Y⋅⋅⋅H−C secondary hydrogen bonds, H⋅⋅⋅H dihydrogen contacts, and non conventional anti‐electrostatic Y δ - ⋯ X δ - interactions. The putative global minimum is triply degenerate, corresponding to the structure of the common dimer of a carboxylic acid. All quantum descriptors of chemical bonding point to a multitude of weak individual interactions within each dimer, whose cumulative effect results in large binding energies and in an attractive fluxional wall of non‐covalent interactions in the interstitial region between the monomers. Abstract : 32 different types of intermolecular interactions are at play stabilizing 416 alanine dimers.