Probing The Conformational Landscape And Thermochemistry Of Dinucleotide Anions Via Helium Nanodroplet Infrared Action Spectroscopy

Thomas, Daniel A

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https://hdl.handle.net/2142/111466 Copy

Description

Title

Probing The Conformational Landscape And Thermochemistry Of Dinucleotide Anions Via Helium Nanodroplet Infrared Action Spectroscopy

Author(s)

Thomas, Daniel A

Contributor(s)

• von Helden, Gert
• Meijer, Gerard
• Greis, Kim
• Lettow, Maike
• Mucha, Eike
• Chang, Rayoon

Issue Date

2021-06-22

Keyword(s)

Ions

Abstract

When molecules are captured in a helium nanodroplet, the rate of cooling to an equilibrium temperature of ca. 0.4 K is faster than the rate of isomerization, resulting in “shock-freezing” that kinetically traps molecules in the local conformational minimum. This unique property enables the study of temperature-dependent conformational equilibria via infrared spectroscopy without the deleterious effects of spectral broadening at higher temperatures.\footnote{D. S. Skvortsov, A. F. Vilesov, \textit{J. Chem. Phys.} \textbf{2009}, \textit{130}, 151101.}$^{, }$\footnote{C. M. Leavitt \textit{et al.}, \textit{J. Phys. Chem. A} \textbf{2014}, \textit{118}, 9692-9700.} We utilize this approach to explore the equilibrium conformer populations of deprotonated dinucleotides, which have been shown previously by ion mobility spectrometry to exhibit a strong temperature dependence.\footnote{J. Gidden, M. T. Bowers, \textit{Eur. Phys. J. D} \textbf{2002}, \textit{20}, 409-419.} Dinucleotide anion species were generated by electrospray ionization, confined in a helium-buffer-gas ion trap at temperatures between 90 and 350 K, and entrained in traversing helium nanodroplets. The infrared spectra of the dinucleotide ions captured in nanodroplets show a strong dependence on pre-pickup ion temperature, consistent with the preservation of conformer populations prior to cooling in the helium nanodroplet. Non-negative matrix factorization was utilized to identify component conformer infrared spectra and thereby determine temperature-dependent conformer populations. Relative enthalpies and entropies of conformers were subsequently obtained from a van ’t Hoff analysis. These initial results demonstrate the promise of this technique to elucidate competing intramolecular interactions and experimentally measure thermochemical parameters for isolated biomolecular ions.\footnote{D. A. Thomas \textit{et al.}, \textit{Phys. Chem. Chem. Phys.} \textbf{2020}, \textit{22}, 18400-18413.}

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Permalink

http://hdl.handle.net/2142/111466

DOI

10.15278/isms.2021.TL08

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