The thermal deactivation of all-trans and 15-cis beta-carotene-excited states in the ionic liquids without and with methylenoxy group

• Published in: Journal of thermal analysis and calorimetry 2015-04, Vol.120 (1), p.627-632
• Main Authors: Pawlak, Krzysztof, Szurkowski, Janusz, Skrzypczak, Andrzej, Bialek-Bylka, Grazyna E.
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Chemistry; Chemistry and Materials Science; Deactivation; Evaporation; Excitation; Excitation spectra; Inorganic Chemistry; Ionic liquids; Isomers; Measurement Science and Instrumentation; Physical Chemistry; Polymer Sciences; Solvents; Volatility
• ISSN: 1388-6150; 1588-2926; 1572-8943
• DOI: 10.1007/s10973-014-4185-5

Photoacoustic spectroscopy was used to study thermal (dark) paths of excited state deactivation of β-carotene in ionic liquids. The dark paths of excited state deactivation of all- trans and 15- cis β-carotene isomers are very important in photosynthesis and medicine. The photoacoustic measurements of β-carotene in traditional solvents are difficult due to fast evaporation of the solvent which leads to concentration fluctuation. Room temperature ionic liquids are good medium for temperature study due to their high thermal stability and low volatility. Dark deactivation of both β-carotene isomers in ionic liquids occurs in a similar way except for an additional path of deactivation of excited state 1 1 A g + (‘ cis ’ peak). The thermal-excited state deactivation of all- trans and 15- cis β-carotene isomers is not sensitive to the ionic liquid structure, in contrast to the radiative path.