MICROWAVE SPECTRUM AND STRUCTURE OF PHENYLACETYLENE···METHANOL COMPLEX

Gupta, Surabhi

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https://hdl.handle.net/2142/122314 Copy

Description

Title

MICROWAVE SPECTRUM AND STRUCTURE OF PHENYLACETYLENE···METHANOL COMPLEX

Author(s)

Gupta, Surabhi

Contributor(s)

• Arunan, Elangannan
• Walker, Nick
• Cummings, Charlotte

Issue Date

2023-06-19

Keyword(s)

• Large amplitude motions
• internal rotation

Abstract

Phenylacetylene (PhAc) is a multifunctional molecule and has been termed a “Hydrogen Bonding Chameleon”ᵃ. In 2008, Patwari and co-workers studied complexes of PhAc with various molecules, including H₂O and CH₃OH, by the IR-UV double resonance spectroscopic techniqueᵇ. This study found that H₂O donates the H-bond to the acetylenic π-system, whereas CH₃OH donates the H-bond to the phenyl π-system. Recently, Suhm’s group used FTIR spectroscopy of supersonic jet expansions to study PhAc with H₂O and CH₃OH and observed that both H₂O and CH₃OH donate H-bond to the acetylenic π-systemᶜ. The acetylenic preference in the PhAc···H₂O complex has already been confirmed by rotational spectroscopyᵈ. In this work, the rotational spectrum of PhAc···CH₃OH complex has been studied. The rotational spectrum of the parent and isotopologues of PhAc···CH₃OH complex was recorded over the 2-8 GHz frequency range using the Chirped Pulse Fourier Transform Microwave (CP-FTMW) Spectrometer at Newcastle University, UK, and from 8-14 GHz using the Pulsed Nozzle Fourier Transform Microwave Spectrometer (PN-FTMW) at IISc Bangalore, India. The structure where CH₃OH donates the H-bond to the acetylenic π-system and CH₃OH accepts a weak H-bond through the ortho hydrogen of the PhAc was observed. The rotational transitions were split, indicating the internal motion of the CH₃ group in CH₃OH. The observed global minimum structure has been compared with several CH₃OH-containing complexes to understand the internal rotation of the CH₃ group and its effect on V₃ barrier height.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Handle URL

https://hdl.handle.net/2142/122314

DOI

https://doi.org/10.15278/isms.2023.6843

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