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Conformational and UV photochemistry studies of amino acids in matrix-isolation FTIR spectroscopy Toh, Shin Yi


The existence of amino acids in interstellar space has been a hot topic among researchers in astronomical science because of the biological molecules relevance to the origin of life. One of the most popular tools employed for the study of amino acids in relation to interstellar chemistry is matrix-isolation spectroscopy, as the cold and isolated environment provided by the matrix crystal mimics various astrophysical media such as interstellar ice. In the presented work, we reported the conformational and UV photochemistry studies of β-alanine and α-alanine via matrix-isolation Fourier transform infrared (MI-FTIR) spectroscopy in solid parahydrogen. This is the first time β-alanine and α-alanine have been registered in parahydrogen matrices, and the crystal has proven to be a more beneficial host over argon matrices for conformational analysis and in-situ UV irradiation experiment. Our claim on the superiority of solid parahydrogen is supported by the detection of high energy amino acids conformers in solid parahydrogen, which are unobserved in noble gas matrices. These conformers are conformer III for β-alanine, and conformer VI and V for α-alanine. As for UV irradiation experiment in solid parahydrogen, we obtained predominantly conformational change for β-alanine. However, α-alanine underwent complete photodestruction to give CO₂ and other unknown photoproducts we are still attempting to identify. Finally, we observed the possibility of β-alanine zwitterion formation in parahydrogen matrices, and are currently in the process of performing high accuracy quantum calculations on several β-alanine zwitterion conformers to assist us in spectral assignment.

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