Ultrafast Chemical Exchange Dynamics of Hydrogen Bonds Observed via Isonitrile Infrared Sensors: Implications for Biomolecular Studies

Joachim Kübel, Giseong Lee, Saik Ann Ooi, Sebastian Westenhoff, Hogyu Han, Minhaeng Cho, Michał Maj

Research output: Contribution to journalArticle


Local probes are indispensable to study protein structure and dynamics with site-specificity. The isonitrile functional group is a highly sensitive and H-bonding interaction-specific probe. Isonitriles exhibit large spectral shifts and transition dipole moment changes upon H-bonding while being weakly affected by solvent polarity. These unique properties allow a clear separation of distinct subpopulations of interacting species and an elucidation of their ultrafast dynamics with two-dimensional infrared (2D-IR) spectroscopy. Here, we apply 2D-IR to quantify the picosecond chemical exchange dynamics of solute-solvent complexes forming between isonitrile-derivatized alanine and fluorinated ethanol, where the degree of fluorination controls their H-bond-donating ability. We show that the molecules undergo faster exchange in the presence of more acidic H-bond donors, indicating that the exchange process is primarily dependent on the nature of solvent-solvent interactions. We foresee isonitrile as a highly promising probe for studying of H-bonds dynamics in the active site of enzymes.

Original languageEnglish
Pages (from-to)7878-7883
Number of pages6
JournalJournal of Physical Chemistry Letters
Issue number24
Publication statusPublished - 2019 Dec 19


ASJC Scopus subject areas

  • Materials Science(all)
  • Physical and Theoretical Chemistry

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