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·(H2O)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/6-311G(d,p) and B3LYP/6-311G(d,p) levels. The spectral analysis reveals that in both isomers the water molecules are forming cyclic hydrogen bond networks around propofols 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.
Original language | English |
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Article number | 074303 |
Journal | Journal of Chemical Physics |
Volume | 137 |
Issue number | 7 |
DOIs | |
Publication status | Published - 21 Aug 2012 |
Externally published | Yes |
Funding
The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under Grant No. 226716 and Spanish Ministry of Science and Innovation-MICINN (Consolider-Ingenio 2010/CSD2007-00013 and CTQ2009-14364/CTQ2011-22923). We would like to thank the staff of FELIX for their support during the experiment. Technical and human support provided by the Laser Facility of the SGIKER (UPV/EHU, MICINN, GV/EJ, ESF) is also gratefully acknowledged. I.L. thanks the GV for a predoctoral fellowship; E.J.C. also acknowledges a “Ramón y Cajal” contract from the MICINN. Computational resources from the SGI/IZO-SGIker and i2BASQUE were used for this work. J.M. thanks the UR for the additional support (API09/10).