title: Complexation of solvents and conformational equilibria in solutions of the simplest calix[4]arenes.
abstract: Structure optimization and calculation of electronic adsorption spectra of 25,26,27,28-tetrahydroxycalix[4]arene and 25,27-dimethoxy-26,28-dihydroxycalix[4]arene conformers have been performed by density-functional theory using hybrid B3LYP functional in cc-p VTZ and cc-p VDZ basis sets in Gaussian 09 package. Analysis of experimental UV-Vis spectra of solutions of 25,26,27,28-tetrahydroxycalix[4]arene, 4-tert-butylcalix[4]arene and 25,27-dimethoxy-26,28-dihydroxycalix[4]arene in various solvents has been carried out. It was shown that the ratio of absorption maxima at characteristic wavelengths at ca. 274 and 283 nm may be used to assess the extent of calix[4]arene/solvent interactions. The conclusion is drawn that spectral characteristics of calix[4]arenes are strongly affected by acid-base interactions.
authors.affiliation: G.A. Krestov Institute of Solution Chemistry, Russian Academy of Sciences, Akademicheskaya Str. 1, 153045 Ivanovo, Russian Federation. Electronic address: ovs@isc-ras.ru.
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Surov
authors.affiliation: G.A. Krestov Institute of Solution Chemistry, Russian Academy of Sciences, Akademicheskaya Str. 1, 153045 Ivanovo, Russian Federation.
authors.forename: Mikhail A
authors.initials: MA
authors.lastname: Krestianinov
authors.affiliation: G.A. Krestov Institute of Solution Chemistry, Russian Academy of Sciences, Akademicheskaya Str. 1, 153045 Ivanovo, Russian Federation.
authors.forename: Marina I
authors.initials: MI
authors.lastname: Voronova
mesh_terms: D047250:Calixarenes / Q000737:chemistry*; D008968:Molecular Conformation; D015394:Molecular Structure; D012996:Solutions; D012997:Solvents / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet
chemical_list: C000599855:25,26,27,28-tetrahydroxycalix(4)arene; C000599856:25,27-dimethoxy-26,28-dihydroxycalix(4)arene; D012996:Solutions; D012997:Solvents; D047250:Calixarenes
keywords: Calix[4]arene; Conformational analysis; Solvent effects; Supramolecular chemistry