Revealing Internal Rotation and 14N Nuclear Quadrupole Coupling in the Atmospheric Pollutant 4-Methyl-2-nitrophenol: Interplay of Microwave Spectroscopy and Quantum Chemical Calculations

Shefali Baweja, Eleonore Antonelli, Safia Hussain, Antonio Fernández-Ramos, Isabelle Kleiner, Ha Vinh Lam Nguyen, M. Eugenia Sanz*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

The structure and interactions of oxygenated aromatic molecules are of atmospheric interest due to their toxicity and as precursors of aerosols. Here, we present the analysis of 4-methyl-2-nitrophenol (4MNP) using chirped pulse and Fabry–Pérot Fourier transform microwave spectroscopy in combination with quantum chemical calculations. The rotational, centrifugal distortion, and 14N nuclear quadrupole coupling constants of the lowest-energy conformer of 4MNP were determined as well as the barrier to methyl internal rotation. The latter has a value of 106.4456(8) cm−1, significantly larger than those from related molecules with only one hydroxyl or nitro substituent in the same para or meta positions, respectively, as 4MNP. Our results serve as a basis to understand the interactions of 4MNP with atmospheric molecules and the influence of the electronic environment on methyl internal rotation barrier heights.

Original languageEnglish
Article number2153
JournalMolecules
Volume28
Issue number5
DOIs
Publication statusPublished - Mar 2023

Keywords

  • ab initio and density functional theory calculations
  • internal rotation
  • large-amplitude motion
  • nuclear quadrupole coupling
  • rotational spectroscopy

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