Coupling of complex aromatic ring vibrations to solvent through hydrogen bonds: Effect of varied on-ring and off-ring hydrogen-bonding substitutions

Nathaniel V. Nucci, J. Nathan Scott, Jane M. Vanderkooi

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)4022-4035
Number of pages14
JournalJournal of Physical Chemistry B
Volume112
Issue number13
DOIs
StatePublished - Apr 3 2008
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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