Coupling of complex aromatic ring vibrations to solvent through hydrogen bonds: effect of varied on-ring and off-ring hydrogen-bonding substitutions.
J Phys Chem B
; 112(13): 4022-35, 2008 Apr 03.
Article
em En
| MEDLINE
| ID: mdl-18331017
ABSTRACT
In this study, we examine the coupling of a complex ring vibration to solvent through hydrogen-bonding interactions. We compare phenylalanine, tyrosine, l-dopa, dopamine, norepinephrine, epinephrine, and hydroxyl-dl-dopa, a group of physiologically important small molecules that vary by single differences in H-bonding substitution. By examination of the temperature dependence of infrared absorptions of these molecules, we show that complex, many-atom vibrations can be coupled to solvent through hydrogen bonds and that the extent of that coupling is dependent on the degree of both on- and off-ring H-bonding substitution. The coupling is seen as a temperature-dependent frequency shift in infrared spectra, but the determination of the physical origin of that shift is based on additional data from temperature-dependent optical experiments and ab initio calculations. The optical experiments show that these small molecules are most sensitive to their immediate H-bonding environment rather than to bulk solvent properties. Ab initio calculations demonstrate H-bond-mediated vibrational coupling for the system of interest and also show that the overall small molecule solvent dependence is determined by a complex interplay of specific interactions and bulk solvation characteristics. Our findings indicate that a full understanding of biomolecule vibrational properties must include consideration of explicit hydrogen-bonding interactions with the surrounding microenvironment.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Aminas Biogênicas
/
Aminoácidos Aromáticos
Tipo de estudo:
Prognostic_studies
Idioma:
En
Ano de publicação:
2008
Tipo de documento:
Article