title: A B3LYP and MP2(full) theoretical investigation on the cooperativity effect between hydrogen-bonding and cation-molecule interactions and thermodynamic property in the 1: 2 (Na⁺: N-(Hydroxymethyl)acetamide) ternary complex.
abstract: The cooperativity effects between the O/N-H∙∙∙O hydrogen-bonding and Na⁺∙∙∙O cation-molecule interactions in the 1: 2 (Na⁺: N-(Hydroxymethyl)acetamide) systems were investigated at the B3LYP/6-311++G**, MP2(full)/6-311++G** and MP2(full)/aug-cc-pvtz levels. The thermodynamic cooperativity calculations were also carried out for two pathways of the ternary-complex formation. The result shows that, in most ternary complexes, the O/N-H∙∙∙O and Na⁺∙∙∙O interactions are weakened in comparison with those in binary systems, leading to the anti-cooperativity effects, in particular in the complexes in which only the Na⁺∙∙∙O interactions exist. Shifts of electron density confirm the existence of anti-cooperativity. The increase of favorable enthalpic contribution leads to the positive cooperativity effect with negative ΔG(coop.) on forming the ternary complex by initial N-(Hydroxymethyl)acetamide dimer followed by addition of Na⁺. In forming the ternary complex by Na⁺∙∙∙N-(Hydroxymethyl)acetamide with the second N-(Hydroxymethyl)acetamide unit, the large unfavorable entropy change leads to the negative cooperativity effect with positive ΔG(coop.). The ternary complex is more easily formed by the pathway in which Na⁺ binds to N-(Hydroxymethyl)acetamide dimer.
authors.affiliation: College of Mining Engineering, Taiyuan University of Technology, Taiyuan, 030024, China.
authors.forename: Guo-rui
authors.initials: GR
authors.lastname: Feng
authors.forename: Ting-ye
authors.initials: TY
authors.lastname: Qi
authors.forename: Wen-jing
authors.initials: WJ
authors.lastname: Shi
authors.forename: Yu-xia
authors.initials: YX
authors.lastname: Guo
authors.forename: Yu-jiang
authors.initials: YJ
authors.lastname: Zhang
authors.forename: Jun
authors.initials: J
authors.lastname: Guo
authors.forename: Li-xun
authors.initials: LX
authors.lastname: Kang
mesh_terms: D000081:Acetamides / Q000737:chemistry*; D000465:Algorithms; D002412:Cations / Q000737:chemistry*; D006860:Hydrogen Bonding; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D011789:Quantum Theory; D013816:Thermodynamics
chemical_list: D000081:Acetamides; D002412:Cations; C030686:acetamide