Aprotic solvents effect on the UV–visible absorption spectra of bixin

Rahmalia, Winda; Fabre, Jean-Charles; Usman, Thamrin; Mouloungui, Zéphirin

doi:10.1016/j.saa.2014.03.119

Cited by 46 publications

(53 citation statements)

References 27 publications

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“…Acetone and dimethyl carbonate were used as solvents because bixin was highly soluble in both these aprotic solvents. We previously reported that the transition energy and molar attenuation coefficient of bixin in dimethyl carbonate were similar to those in acetone [ 28 ]. Dimethyl carbonate would therefore be an appropriate alternative to volatile organic solvents like the nonpolar aprotic solvent acetone.…”

Section: Introductionmentioning

confidence: 96%

Adsorption Characteristics of Bixin on Acid- and Alkali-Treated Kaolinite in Aprotic Solvents

Rahmalia

Fabre

Usman

et al. 2018

Bioinorganic Chemistry and Applications

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The adsorption of bixin in aprotic solvents onto acid- and alkali-treated kaolinite was investigated. Kaolinite was treated three times, for 6 h each, with 8 M HCl or 5 M KOH. The adsorbents were characterized by XRD, FT-IR, EDS, and BET-N2. The effects of contact time and dye concentration on adsorption capacity and kinetics, electronic transition of bixin before and after adsorption, and also mechanism of bixin-kaolinite adsorption were investigated. Dye adsorption followed pseudo-second order kinetics and was faster in acetone than in dimethyl carbonate. The best adsorption results were obtained for KOH-treated kaolinite. In both of the solvents, the adsorption isotherm followed the Langmuir model and adsorption capacity was higher in dimethyl carbonate (q m = 0.43 mg/g) than in acetone (0.29 mg/g). The adsorption capacity and kinetics of KOH-treated kaolinite (q m = 0.43 mg/g, k 2 = 3.27 g/mg·min) were better than those of HCl-treated kaolinite (q m = 0.21 mg/g, k 2 = 0.25 g/mg·min) and natural kaolinite (q m = 0.18 mg/g, k 2 = 0.32 g/mg·min). There are shift in the band position of maximum intensity of bixin after adsorption on this adsorbent. Adsorption in this system seemed to be based essentially on chemisorption due to the electrostatic interaction of bixin with the strong basic and reducing sites of kaolinite.

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Section: Introductionmentioning

confidence: 96%

Adsorption Characteristics of Bixin on Acid- and Alkali-Treated Kaolinite in Aprotic Solvents

Rahmalia

Fabre

Usman

et al. 2018

Bioinorganic Chemistry and Applications

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“…Britton et al 49 showed that the UV spectral shift of carotenoids in solution depends on the polarizability rather than the polarity of the solvent; as the refractive index of the solvent increases a spectral shift to longer wavelength is observed. Recently, Rahmalia et al 30 showed that the S 0 → S 2 transition energy of bixin in solution was dependent mainly on the refractive index of the solvents and the bixin-solvent dispersion interaction. The electronic behavior of bixin in solvents with different polarities experiences a different chemical environment, however, it has been shown that a slight perturbation of the polyenic electronic distribution occurs when the solute is in contact with the solvent molecules.…”

Section: Resultsmentioning

confidence: 99%

“…For that DMSO and CHCl 3 were used. Both are aprotic polar solvents which efficiently solubilize cis-bixin; 30 CHCl 3 is the most efficient solvent for the quantitative extraction of bixin, 29 whereas DMSO is commonly used to solubilize compounds in biological assays. [58][59][60] The analyses were performed with an increasing number of solvent molecules in which each one has been inserted in different orientations as shown in Figures 6A and 6B.…”

Section: Resultsmentioning

confidence: 99%

“…Despite both solvents have similar polarizability values they possess very different dielectric constants, which could explain the differences observed in solvation around the cis-bixin. According to Rahmalia et al, 30 the extension of the bixin conjugated chain may be responsible for the preponderance of solute-solvent interactions which were more pronounced in DMSO and CHCl 3 . The absorbance at λ max of bixin increased linearly with increasing concentration of aprotic polar solvents mainly in CHCl 3 .…”

Section: Molecular Dynamicsmentioning

confidence: 97%

“…28,29 It is therefore soluble in most polar organic solvents, conferring an orange coloration to the solution, but is largely insoluble in vegetable oil 29 and aprotic apolar solvents. 30 Seeds and powder form are commercially available as annatto and their main orange-red colored component is referred to as bixin (cis-bixin or Z-bixin). This compound has been extensively used as a food colorant 27,28 with a wide range of pharmacological activities 31,32 and due to its physicochemical properties it is used as a sensitizer for dye sensitized solar cells.…”

Section: Introductionmentioning

confidence: 99%

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Understanding Solvent/Bixin Interactions by Raman Spectroscopy

Maia

Rimulo

Oliveira

et al. 2020

J. Braz. Chem. Soc.

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In this work, Raman spectroscopy and density functional theory (DFT) calculations have been used in order to understand the nature of the interaction between the carotenoid bixin and organic solvents with dielectric constant varying from ca. 2 (toluene) to ca. 47 (dimethyl sulfoxide). Raman shifts registered for the main carotenoid marker band, the C=C stretching mode (1525-1533 cm −1), were used as a probe to monitor spectral changes due to chemical interaction between bixin in the solid state with the analogous solvated species. Raman spectra of bixin in solution showed significant bathochromic shifts in the wavenumber position of ν(C=C) when compared with the solid state. Among the solutions, subtle differences were observed and the polarizability rather than dielectric constant of the solvents seems to be a more appropriate parameter to explain the differences in Raman shifts which could be correlated with the solvation degree of bixin. Correlation between DFT analysis and molecular dynamics simulations obtained for cis-bixin in DMSO and CHCl 3 demonstrated that the interaction of the solute with the respective solvents occurs in specific portions of the molecule, however, this result was not confirmed by the experimental data since bixin is solvated by larger numbers of solvent molecules.

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