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2,2,3,3,3-Pentafluoro-1-propanol and its dimer: structural diversity, conformational conversion, and tunnelling
Bowei Wu1, Nathan A Seifert1,2, Aran Insausti1,3,4
1Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta, T6G 2G2, Canada. yunjie.xu@ualberta.ca.
Physical Chemistry Chemical Physics : PCCP
|June 10, 2022
Summary
This study measured rotational spectra of pentafluoropropanol (PFP) monomers and dimers. It identified stable PFP conformers and analyzed their interactions, revealing insights into fluorination effects.
Area of Science:
- Physical Chemistry
- Spectroscopy
- Computational Chemistry
Background:
- Understanding the conformational landscape and intermolecular interactions of fluorinated alcohols is crucial for predicting their behavior in various chemical environments.
- 2,2,3,3,3-pentafluoro-1-propanol (PFP) is a fluorinated alcohol whose structural properties and interactions are not fully characterized.
Purpose of the Study:
- To experimentally determine the stable monomeric and dimeric conformers of PFP using microwave spectroscopy.
- To computationally predict and analyze the structural diversity and stability of PFP conformers and dimers.
- To investigate the non-covalent intermolecular interactions within PFP dimers and compare the effects of fluorination with non-fluorinated analogs.
Main Methods:
- Measurement of rotational spectra of PFP monomers and dimers using cavity and chirped pulse Fourier transform microwave spectrometers.
- Conformational search using the CREST tool and Density Functional Theory (DFT) calculations (B3LYP-D3(BJ)/def2-QZVP).
- Analysis of non-covalent interactions using Quantum Theory of Atoms in Molecules (QTAIM) and Non-Covalent Interaction (NCI) analyses.
Main Results:
- Observed and assigned rotational spectra for the two most stable monomeric PFP conformers and their isotopologues.
- Identified five stable PFP dimer conformers, matching the most stable predicted by computational methods, exclusively formed from the most stable monomer subunits.
- Developed a kinetic and thermodynamic model to explain conformer observation/non-observation, validated by the 'argon test'.
Conclusions:
- The study successfully characterized the most stable monomeric and dimeric conformers of PFP, providing experimental evidence for their structures.
- Computational methods accurately predicted the stable conformers, highlighting the structural diversity of PFP dimers.
- The findings offer insights into the role of fluorination in shaping the conformational preferences and intermolecular interactions of alcohols.
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