title: A combined spectroscopic and theoretical study of propofol·(H2O)3.
abstract: Propofol (2,6-di-isopropylphenol) is probably the most widely used general anesthetic. Previous studies focused on its complexes containing 1 and 2 water molecules. In this work, propofol clusters containing three water molecules were formed using supersonic expansions and probed by means of a number of mass-resolved laser spectroscopic techniques. The 2-color REMPI spectrum of propofol[middle dot](H(2)O)(3) contains contributions from at least two conformational isomers, as demonstrated by UV/UV hole burning. Using the infrared IR/UV double resonance technique, the IR spectrum of each isomer was obtained both in ground and first excited electronic states and interpreted in the light of density functional theory (DFT) calculations at M06-2X/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels. The spectral analysis reveals that in both isomers the water molecules are forming cyclic hydrogen bond networks around propofol's OH moiety. Furthermore, some evidences point to the existence of isomerization processes, due to a complicated conformational landscape and the existence of multiple paths with low energy barriers connecting the different conformers. Such processes are discussed with the aid of DFT calculations.
authors.affiliation: Dpto. de Química Física, Facultad de Ciencia y Tecnología, Universidad del País Vasco-UPV/EHU, Bo Sarriena s/n, Leioa 48940, Spain.
authors.forename: Iker
authors.initials: I
authors.lastname: León
authors.forename: Emilio J
authors.initials: EJ
authors.lastname: Cocinero
authors.forename: Judith
authors.initials: J
authors.lastname: Millán
authors.forename: Anouk M
authors.initials: AM
authors.lastname: Rijs
authors.forename: Imanol
authors.initials: I
authors.lastname: Usabiaga
authors.forename: Alberto
authors.initials: A
authors.lastname: Lesarri
authors.forename: Fernando
authors.initials: F
authors.lastname: Castaño
authors.forename: José A
authors.initials: JA
authors.lastname: Fernández
mesh_terms: D018686:Anesthetics, Intravenous / Q000737:chemistry; D006993:Hypnotics and Sedatives / Q000737:chemistry; D015742:Propofol / Q000737:chemistry*; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D014867:Water / Q000737:chemistry*
chemical_list: D018686:Anesthetics, Intravenous; D006993:Hypnotics and Sedatives; D014867:Water; D015742:Propofol