title: Molecular hydration of propofol dimers in supersonic expansions: formation of active centre-like structures.
abstract: Spectroscopic studies of molecular aggregates are a powerful tool to understand the weak interactions between molecules. Here, propofol2(H2O)6,7 clusters were formed in supersonic expansions and their electronic and infrared spectroscopy was explored using several mass-resolved laser-based spectroscopic techniques. Using REMPI, their S1 ← S0 electronic spectrum was obtained with vibrational resolution, while the UV/UV hole burning revealed the presence of a single isomer of propofol2(H2O)6 and of two isomers of propofol2(H2O)7. Employment of IR/UV double resonance yielded the IR spectrum in the OH stretch region. Comparison with the spectra predicted for the structures calculated at the M06-2X/6-31+G(d) level demonstrated that the two propofol molecules interact mainly through C-Hπ contacts between the lipophilic sides of the molecules, while the hydroxyl moieties are in close contact, forming a kind of "active centre" with which the water molecules interact, forming polyhedral structures.
authors.affiliation: Department of Physical Chemistry, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Bo Sarriena s/n, Leioa 48940, Spain. josea.fernandez@ehu.es.
authors.forename: Iker
authors.initials: I
authors.lastname: León
authors.forename: Judith
authors.initials: J
authors.lastname: Millán
authors.forename: Emilio J
authors.initials: EJ
authors.lastname: Cocinero
authors.forename: Alberto
authors.initials: A
authors.lastname: Lesarri
authors.forename: José A
authors.initials: JA
authors.lastname: Fernández
mesh_terms: D019281:Dimerization; D057927:Hydrophobic and Hydrophilic Interactions; D015394:Molecular Structure; D015742:Propofol / Q000737:chemistry*; D011789:Quantum Theory; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D015742:Propofol