Fluorescence emission characterization of all-trans and 15-cis-β-carotene in imidazolium based room temperature ionic liquids

• The influence of temperature on the β-carotene isomer stability was investigated.
• The fluorescence of all-trans and 15-cis-β-carotene was measured in ionic liquids.
• The absorption of all-trans and 15-cis-β-carotene was measured in ionic liquids.

β-Carotene is an important molecule in the photosynthetic system, medicine and pharmacy, and has two important functions, photoprotection and light harvesting. Eleven different ionic liquids were designed, synthesized and purified for our experiment in order to obtain samples with predicted physicochemical parameters. The absorption and fluorescence emission spectra of all-trans and 15-cis-β-carotene, at concentrations of 5 μM and 50 μM, in different ionic liquids were recorded. The influence of temperature (in the physiological range important for the isomer stability) on the absorption and fluorescence emission spectra of the carotenes was investigated.