Monte Carlo Structure Simulations for Aqueous 1,4-Dioxane Solutions

• Published in: The journal of physical chemistry. B 2008-02, Vol.112 (7), p.2085-2094
• Main Authors: Nagy, Peter I., Völgyi, Gergely, Takács-Novák, Krisztina
• Format: Article
• Language: English
• Subjects: Computer Simulation; Dioxanes - chemistry; Hydrogen Bonding; Molecular Structure; Monte Carlo Method; Solutions; Water
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp075603c

Monte Carlo simulations in the NpT ensembles have been performed for the structure exploration of aqueous 1,4-dioxane solutions. Three different systems with all-atom dioxane:TIP4P water molar compositions of 2:500 (code:D2), 8:465 (D8), and 17:425 (D17) modeled solutions of 0.22, 0.88, and 1.86 mol/dm3 concentrations, respectively, at T = 298 K and p = 1 atm. The calculated solution densities increase from 0.992 to 1.002 g/cm3 with increasing dioxane concentration and approach the experimentally determined densities within 1%. This close agreement was achieved by utilizing RESP charges fitted to the in-solution IEF-PCM/B3LYP/6-31G* electrostatic potential of dioxane taken in its chair conformation and recently developed C, H steric parameters for ethers for calculations with a 12-6-1 all-atom potential. Solution structure analyses pointed out that the dioxane molecules arrange in the solutions with favorable distances of 4−8 Å for the ring symmetry centers. Within this range not only pairs of rings but triangular triads and tetrads have also been observed with center−center distances