Excitation followed by stimulated-emission from diabatic levels in all-trans- and 15-cis-β-carotenes: Effects of molecular symmetry and solvent polarity

Antioxidant Activity of Flavonoids of Different Polarity, Assayed by Modified ABTS Cation Radical Decolorization and EPR Technique

“…Aggregated forms of carotene are less effective antioxidants than monomeric forms (Cantrell et al, 2003). Such peaks were not observed in our electronic absorption steady-state study, but recent time-resolved (fs) stimulated emission data from Bialek- Bylka et al (2008) indicate the presence of aggregated forms of β-carotene, so our conclusion that all-trans β-carotene is a less efficient antioxidant than the investigated flavonoids is open to question.…”

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

“…6) are the energy states 3 1 A g -(0) and 1 1 B u -(1), respectively. The small shift of energy (PAS measurements) in comparison to the data (fluorescence technique) obtained in our previous papers [9,23] is due to the higher concentration of b-carotene (necessary for PAS measurements) and the lower signal/noise ratio. The energy level PAS-III is close to the value of energy state 1 1 B u -(0) reported by Sashima et al [22].…”

“…The non-radiative deactivations of both b-carotene isomers in the ionic liquids occur via Fig. 6 The energy levels of b-carotene isomers in n-hexane and RTILs (solid and dashed lines, respectively) obtained from our previous data [23] and PAS measurements (dashed dotted lines)…”

Inner Filter Effect in the Fluorescence Emission Spectra of Room Temperature Ionic Liquids with-β-Carotene

“…Influence of the ionic liquid viscosity has been detected by the fluorescence emission and absorption spectra. Important information is that the new electronic states of -carotene were found in the mixture of RTIL and DMF (Bialek-Bylka, 2008). Figure 8 (C1).…”

“…Unique fluorescence properties of β-carotene in room temperature ionic liquids (RTIL) (Bialek-Bylka et al, 2007) and new (β-carotene) electronic states (3A g -and 1B u -) of both important in photosynthesis isomers: all-trans and 15-cis in ionic liquid with dimethylformamide (DMF) were found (Bialek-Bylka et al, 2008) and also a sensor detecting the methoxy group in the cation part of imidazolium ionic liquid was developed by us (Pawlak et al, 2009). In order to determine a detailed answer to the unique fluorescence properties, around 100 times higher fluorescence yield of β-carotene in (IL1) (1-methyl-3-octyloxymethylimidazolium tetrafluoroborate) than in standard solvent nhexane, the designed structures of RTILs were synthesized and carefully purified: 1-methyl-3-octyloxymethylimidazolium tetrafluoroborate (IL1 …”