Cryogenic ion spectroscopy of adenine complexes containing alkali metal cations.

Han Jun Eun, Shun-Ich Ishiuchi, Ji Young Baek, Seulgi Lee, Jiyoung Heo, Masaaki Fujii, Nam Joon Kim

Physical chemistry chemical physics : PCCP 2021 Mar 21

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Cryogenic ion spectroscopy was used to characterize adenine complexes containing alkali metal cations (M+A, M = Cs, Rb, K, Na, and Li) produced by electrospray ionization. The ultraviolet (UV) photodissociation spectra of the complexes stored in a cryogenic ion trap exhibited well-resolved vibronic bands near their origin bands of the S0-S1 transition. The UV-UV hole-burning and infrared ion-dip spectra showed that all the M+A ions in the ion trap were single isomers of M+A7a, where the M+ ion was not bound to canonical 9H-adenine (A9) but bound to a rare tautomer, 7H-adenine (A7). Density functional theory calculations showed lower tautomerization barriers for M+A9 than for bare A9 in aqueous solution. We suggest that M+ ions not only play a catalytic role in the tautomerization of A9 to A7 but also increase the tautomerization yield by forming stable M+A7a isomers.

Citation

Han Jun Eun, Shun-Ich Ishiuchi, Ji Young Baek, Seulgi Lee, Jiyoung Heo, Masaaki Fujii, Nam Joon Kim. Cryogenic ion spectroscopy of adenine complexes containing alkali metal cations. Physical chemistry chemical physics : PCCP. 2021 Mar 21;23(11):6783-6790