Inter- and intramolecular hydrogen bonding in phenol derivatives: a model system for poly-L-tyrosine.
The ultrafast dynamics of solutions of phenol and two phenol derivatives--hydroquinone (1,4-benzenediol) and pyrocatechol (1,2-benzenediol)--have been studied with Optically Heterodyne-Detected Optical Kerr-Effect (OHD-OKE) spectroscopy. The solvents, methanol and acetonitrile, were selected to provide strong and weak solvent-solute hydrogen-bonding interactions, respectively, while pyrocatechol features an intramolecular hydrogen bond. Together these provide a series of model systems for polypeptides such as polytyrosine, which facilitate the direct study of inter- and intramolecular hydrogen bonding. A broad contribution to the Raman spectral density of the methanol solutions at frequencies between 150 and 300 cm(-1) has been observed that is absent in acetonitrile. This contribution has been assigned to solvent-solute hydrogen-bond stretching vibrations. The OHD-OKE response of poly-L-tyrosine has been measured and was found to contain a similar contribution. Density functional theory geometry optimizations and normal mode calculations have been performed using the B3LYP hybrid functional and 6-311++G** basis set. These have yielded a complete assignment of the low-frequency Raman and far-infrared spectra of pyrocatechol for the first time, which has provided information on the nature of the intramolecular hydrogen bond of pyrocatechol.
Hunt
Neil T
NT
Department of Physics, University of Strathclyde, John Anderson Building, 107 Rottenrow East, Glasgow G4 0NG, Scotland, United Kingdom.
Turner
Andrew R
AR
Wynne
Klaas
K
D003198:Computer Simulation; D006860:Hydrogen Bonding; D008956:Models, Chemical; D010455:Peptides / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D012680:Sensitivity and Specificity; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013997:Time Factors; D014732:Vibration
D010455:Peptides; D010636:Phenols; C017663:polytyrosine