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Solvent effect on the spectral properties of Neutral Red.

Rauf MA, Soliman AA, Khattab M - Chem Cent J (2008)

Bottom Line: This showed that the unified scale for estimating the solvent effect on the absorption of the Neutral Red dye is more adopted and more applicable than the pi* scale model.The unified scale for estimating the solvent effect on the absorption of Neutral Red dye is more adopted and more applicable than the pi* scale model.This may be due to complications from both pi-pi* charge transfer interactions and incomplete complexation of the solute; these effects are averaged out in the derived beta and pi parameters and thus limit their applicability.

View Article: PubMed Central - HTML - PubMed

Affiliation: Chemistry Department, UAE University, Al-Ain, UAE. raufmapk@yahoo.com

ABSTRACT

Background: The study was aimed at investigating the effect of various solvents on the absorption spectra of Neutral Red, a dye belonging to the quinone-imine class of dyes. The solvents chosen for the study were water, ethanol, acetonitrile, acetone, propan-1-ol, chloroform, nitrobenzene, ethyleneglycol, acetic acid, DMSO and DMF.

Results: The results have shown that the absorption maxima of dyes are dependent on solvent polarity. In non-hydrogen-bond donating solvents, solvation of dye molecules probably occurs via dipole-dipole interactions, whereas in hydrogen-bond donating solvents the phenomenon is more hydrogen bonding in nature. To estimate the contribution of the different variables on the wave number of the Neutral Red dye, regression analyses using the ECW model were compared with the pi* scale model. This showed that the unified scale for estimating the solvent effect on the absorption of the Neutral Red dye is more adopted and more applicable than the pi* scale model.

Conclusion: Absorption maxima of dyes are dependent on solvent polarity. Solvation of dye molecules probably occurs via dipole-dipole interactions in non-hydrogen-bond donating solvents, whereas in hydrogen-bond donating solvents the phenomenon is more hydrogen bonding in nature. The unified scale for estimating the solvent effect on the absorption of Neutral Red dye is more adopted and more applicable than the pi* scale model. This may be due to complications from both pi-pi* charge transfer interactions and incomplete complexation of the solute; these effects are averaged out in the derived beta and pi parameters and thus limit their applicability.

No MeSH data available.


Related in: MedlinePlus

(A) Absorption shift of dye solution in non-hydrogen-bond donating solvents as a function of solvent polarity parameter φ(ε, n), (B) Absorption shift of dye solution in hydrogen bonding solvents as a function of solvent polarity parameter φ(ε, n).
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Figure 5: (A) Absorption shift of dye solution in non-hydrogen-bond donating solvents as a function of solvent polarity parameter φ(ε, n), (B) Absorption shift of dye solution in hydrogen bonding solvents as a function of solvent polarity parameter φ(ε, n).

Mentions: where, ε is the dielectric constant and n is the refractive index and both these quantities reflect the freedom of motion of electrons in the solvent and the dipole moment of the molecules. Specific solvent effects occur by interactions of the solvent and the chromophores. Figure 5A and 5B shows the trend when the spectral position (λmax) of the dyes in various solvents (non-protic and protic) were plotted against the solvent polarity parameter φ(ε, n).


Solvent effect on the spectral properties of Neutral Red.

Rauf MA, Soliman AA, Khattab M - Chem Cent J (2008)

(A) Absorption shift of dye solution in non-hydrogen-bond donating solvents as a function of solvent polarity parameter φ(ε, n), (B) Absorption shift of dye solution in hydrogen bonding solvents as a function of solvent polarity parameter φ(ε, n).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2571090&req=5

Figure 5: (A) Absorption shift of dye solution in non-hydrogen-bond donating solvents as a function of solvent polarity parameter φ(ε, n), (B) Absorption shift of dye solution in hydrogen bonding solvents as a function of solvent polarity parameter φ(ε, n).
Mentions: where, ε is the dielectric constant and n is the refractive index and both these quantities reflect the freedom of motion of electrons in the solvent and the dipole moment of the molecules. Specific solvent effects occur by interactions of the solvent and the chromophores. Figure 5A and 5B shows the trend when the spectral position (λmax) of the dyes in various solvents (non-protic and protic) were plotted against the solvent polarity parameter φ(ε, n).

Bottom Line: This showed that the unified scale for estimating the solvent effect on the absorption of the Neutral Red dye is more adopted and more applicable than the pi* scale model.The unified scale for estimating the solvent effect on the absorption of Neutral Red dye is more adopted and more applicable than the pi* scale model.This may be due to complications from both pi-pi* charge transfer interactions and incomplete complexation of the solute; these effects are averaged out in the derived beta and pi parameters and thus limit their applicability.

View Article: PubMed Central - HTML - PubMed

Affiliation: Chemistry Department, UAE University, Al-Ain, UAE. raufmapk@yahoo.com

ABSTRACT

Background: The study was aimed at investigating the effect of various solvents on the absorption spectra of Neutral Red, a dye belonging to the quinone-imine class of dyes. The solvents chosen for the study were water, ethanol, acetonitrile, acetone, propan-1-ol, chloroform, nitrobenzene, ethyleneglycol, acetic acid, DMSO and DMF.

Results: The results have shown that the absorption maxima of dyes are dependent on solvent polarity. In non-hydrogen-bond donating solvents, solvation of dye molecules probably occurs via dipole-dipole interactions, whereas in hydrogen-bond donating solvents the phenomenon is more hydrogen bonding in nature. To estimate the contribution of the different variables on the wave number of the Neutral Red dye, regression analyses using the ECW model were compared with the pi* scale model. This showed that the unified scale for estimating the solvent effect on the absorption of the Neutral Red dye is more adopted and more applicable than the pi* scale model.

Conclusion: Absorption maxima of dyes are dependent on solvent polarity. Solvation of dye molecules probably occurs via dipole-dipole interactions in non-hydrogen-bond donating solvents, whereas in hydrogen-bond donating solvents the phenomenon is more hydrogen bonding in nature. The unified scale for estimating the solvent effect on the absorption of Neutral Red dye is more adopted and more applicable than the pi* scale model. This may be due to complications from both pi-pi* charge transfer interactions and incomplete complexation of the solute; these effects are averaged out in the derived beta and pi parameters and thus limit their applicability.

No MeSH data available.


Related in: MedlinePlus