# Preparation of Tautomer-Pure Molecular Beams by Electrostatic Deflection

## TL;DR

This paper shows how to separate tautomers in a molecular beam using electrostatic deflection, enabling detailed study of individual tautomers.

## Contribution

The first experimental separation of tautomers in a molecular beam and production of tautomerically pure samples.

## Key findings

- Tautomers in a molecular beam can be separated via electrostatic deflection.
- Tautomer-resolved photoelectron spectra were collected using femtosecond multiphoton ionization.
- The 2-pyridone/2-hydroxypyridine system was used as a model for tautomer separation.

## Abstract

Tautomers are ubiquitous throughout chemistry and typically
considered
inseparable in solution. Yet (bio)chemical activity is highly tautomer-specific,
with common examples being the amino and nucleic acids. While tautomers
exist in an equilibrium in solution, in the cold environment of a
molecular beam the barrier to tautomerization is typically much too
high for interconversion, and tautomers can be considered separate
species. Here we demonstrate the first separation of tautomers within
a molecular beam and the production of tautomerically pure gas-phase
samples. We show this for the 2-pyridone/2-hydroxypyridine system,
an important structural motif in both uracil and cytosine. Spatial
separation of the tautomers is achieved via electrostatic deflection
in strong inhomogeneous fields. We furthermore collect tautomer-resolved
photoelectron spectra using femtosecond multiphoton ionization. This
paves the way for studying the structure–function–dynamic
relationship on the level of individual tautomers, using approaches
that typically lack the resolution to do so, such as ultrafast dynamics
experiments.