Collision-assisted stripping for determination of microsolvation-dependent protonation sites in hydrated clusters by cryogenic ion trap infrared spectroscopy: the case of benzocaineH+(H2O)n. Issue 10 (24th February 2022)

• Record Type: Journal Article
• Authors: Hirata, Keisuke; Haddad, Fuad; Dopfer, Otto; Ishiuchi, Shun-ichi; Fujii, Masaaki
• Is Part Of: Physical chemistry chemical physics. Volume 24:Issue 10(2022)
• Page Start: 5774
• Page End: 5779
• Publication Date: 2022-02-24
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/d1cp05762f
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Protonation sites in hydrated clusters can be clearly determined by CAS-IRPD (collision-assisted stripping infrared photodissociation) spectroscopy as shown for the example of hydrated protonated benzocaine. Abstract : The protonation site of molecules can be varied by their surrounding environment. Gas-phase studies, including the popular techniques of infrared spectroscopy and ion mobility spectrometry, are a powerful tool for the determination of protonation sites in solvated clusters but often suffer from inherent limits for larger hydrated clusters. Here, we present collision-assisted stripping infrared (CAS-IR) spectroscopy as a new technique to overcome these problems and apply it in a proof-of-principle experiment to hydrated clusters of protonated benzocaine (H + BC), which shows protonation-site switching depending on the degree of hydration. The most stable protomer of H + BC in the gas phase (O-protonated) is interconverted into its most stable protomer in aqueous solution (N-protonated) upon hydration with three water molecules. CAS-IR spectroscopy enables us to unambiguously assign protonation sites and quantitatively determine the relative abundance of various protomers.