title: A theoretical investigation into the cooperativity effect between the H∙∙∙O and H∙∙∙F⁻ interactions and electrostatic potential upon 1:2 (F⁻:N-(Hydroxymethyl)acetamide) ternary-system formation.
abstract: The cooperativity effects between the O/N-H∙∙∙F(-) anionic hydrogen-bonding and O/N-H∙∙∙O hydrogen-bonding interactions and electrostatic potentials in the 1:2 (F(-):N-(Hydroxymethyl)acetamide (signed as "ha")) ternary systems are investigated at the B3LYP/6-311++G** and MP2/6-311++G** levels. A comparison of the cooperativity effect in the "F(-)∙∙∙ha∙∙∙ha" and "FH∙∙∙ha(-)∙∙∙ha" systems is also carried out. The result shows that the increase of the H∙∙∙O interaction energy in the O-H∙∙∙O-H, N-H∙∙∙O-H or N-H∙∙∙O = C link is more notable than that in the O-H∙∙∙O = C contact upon ternary-system formation. The cooperativity effect is found in the complex formed by the O/N-H∙∙∙F(-) and O/N-H∙∙∙O interactions, while the anti-cooperativity effect is present in the system with only the O/N-H∙∙∙F(-) H-bond or the "FH∙∙∙ha(-)∙∙∙ha" complex by the N(-)∙∙∙H-F contact. Atoms in molecules (AIM) analysis and shift of electron density confirm the existence of cooperativity. The most negative surface electrostatic potential (V(S,min)) correlates well with the interaction energy E' int.(ha∙∙∙F-) and synergetic energy E(syn.), respectively. The relationship between the change of V(S,min) (i.e., ΔV(S,min)) and E(syn.) is also found.
authors.affiliation: Department of Pharmacy, Shanxi Medical University, Taiyuan, 030001, China.
authors.forename: Qing-Ping
authors.initials: QP
authors.lastname: Tian
authors.forename: Yan-Hong
authors.initials: YH
authors.lastname: Wang
authors.forename: Wen-Jing
authors.initials: WJ
authors.lastname: Shi
authors.forename: Shu-Qin
authors.initials: SQ
authors.lastname: Song
authors.forename: Hai-Fei
authors.initials: HF
authors.lastname: Tang