SO2 capture by tricyanomethanide ionic liquids: Unraveling anion-gas interactions by resonance Raman spectroscopy

• Published in: Chemical physics letters Vol. 784; p. 139106
• Main Authors: Morselli, Giovanni R., Ando, Rômulo A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-12-2021
• Subjects: Charge transfer; Gas absorption; Room temperature ionic liquids; Solvation; Sulfur dioxide; Gas absorption; Solvation; Room temperature ionic liquids; Charge transfer; Sulfur dioxide
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/j.cplett.2021.139106

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•Normal Raman spectra suggests only dispersion forces between ions and SO2.•Resonance Raman spectra evidences charge transfer interactions between TCM and SO2.•The charge transfer solvation states contribute to the high absorption of SO2.
Interactions concerning the high SO2 absorption capacity in 1-butyl-3-methyilimidazolium tricyanomethanide (BMITCM) were analyzed through Raman spectroscopy. The SO2 symmetric stretching band, νs(SO2), remained equal in shape and wavenumber regardless the SO2 molar fraction, suggesting no specific interaction between TCM and SO2. However, by increasing the Raman excitation energy from 568 to 405 nm, a pre-resonance condition was reached, where a shifting and broadening of νs(SO2) is noticed. Such results evidence solvation states where charge transfer interactions between TCM and SO2 prevail, corroborating the high absorption capacity of TCM based ionic liquids.