title: Effect of solvation on pinched cone-pinched cone interconversion of tetraethoxycalix[4]arene and tetraethoxythiacalix[4]arene.
abstract: The pinched cone-pinched cone interconversion (PCI) of tetraethoxy substituted calix[4]arene and thiacalix[4]arene was studied by means of molecular dynamics using the GAFF force field and quantum mechanics. Influence of solvent was expressed by changes in cavity geometries as well as in free energy barriers that were calculated using constrained MD simulations. Water and chloroform were found to reduce the energy barriers in comparison with vacuum simulations. Only qualitative agreement between energy barriers calculated by MD and experimental values was achieved. Also, quantum chemical calculations were performed with the RI-MP2 method, and a better description of PCI was achieved than that previously obtained by HF or DFT methods. The combination of qualitative MD data on solvated systems with RI-MP2 gas-phase data gave us very good agreement with experimental results.
authors.affiliation: National Centre for Biomolecular Research, Faculty of Science, Masaryk University in Brno, Kotlárská 2, CZ-611 37 Brno, Czech Republic.
authors.forename: Jirí
authors.initials: J
authors.lastname: Matousek
authors.forename: Petr
authors.initials: P
authors.lastname: Kulhánek
authors.forename: Michal
authors.initials: M
authors.lastname: Cajan
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Koca
mesh_terms: D047250:Calixarenes / Q000737:chemistry*; D008968:Molecular Conformation; D010636:Phenols / Q000737:chemistry*; D012995:Solubility; D012997:Solvents / Q000737:chemistry*
chemical_list: D010636:Phenols; D012997:Solvents; C121325:calix(4)arene; D047250:Calixarenes