title: The hydration structure of 18-crown-6/K+ complex as studied by Monte Carlo simulation using ab initio fitted potential.
abstract: The intermolecular potential between a 18-crown-6/K+ complex and a water molecule is derived from 1200 energy points obtained from quantum chemical calculations using the 6-31G** basis set. The ab initio fitted potential was then applied to study the structural properties of the complex in an aqueous solution using the Monte Carlo simulation method. The radial distribution function (RDF) centered at K+ to the oxygen atom of water shows a sharp first peak at 2.88 A. The corresponding coordination number, integrated up to the first minimum at 3.76 A, is 2 water molecules. The results indicate clearly that the 18-crown-6/K+ complex was solvated by the two nearest neighbors, one above and other below the ligand's plane. Evaluation was focused on the precise position and orientation of the two water molecules. It was found that the oxygen atoms of the two nearest neighbors bind to the K+ while their hydrogen atoms rotate freely around the vector perpendicular to the ligand's molecular plane.
authors.affiliation: Physics Department and Capability Building Center for Nanoscience and Nanotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Sriprajak
authors.initials: S
authors.lastname: Krongsuk
authors.forename: Teerakiat
authors.initials: T
authors.lastname: Kerdcharoen
authors.forename: Supot
authors.initials: S
authors.lastname: Hannongbua
mesh_terms: D002414:Cations, Monovalent / Q000737:chemistry; D003198:Computer Simulation; D043844:Crown Ethers / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry; D015394:Molecular Structure; D009010:Monte Carlo Method; D010100:Oxygen / Q000737:chemistry; D011188:Potassium / Q000737:chemistry*; D011789:Quantum Theory; D012995:Solubility; D014867:Water / Q000737:chemistry*
chemical_list: D002414:Cations, Monovalent; D043844:Crown Ethers; D014867:Water; C015762:18-crown-6; D006859:Hydrogen; D011188:Potassium; D010100:Oxygen