Table 5 Regression fits to Kamlet–Abboud–Taft solvatochromic parameters for absorbance, fluorescence and Stokes’ shift for Azo form of dyes in organic solvents.
Dyes | \((\tilde{v}_{{}} )_{0} (10^{3} cm^{ - 1} )\) | \(a\,\left( {10^{3} cm^{ - 1} } \right)\) | \(b\;\left( {10^{3} cm^{ - 1} } \right)\) | \(s\,\left( {10^{3} cm^{ - 1} } \right)\) | R2 |
|---|---|---|---|---|---|
Ponceau 4R | |||||
Absorbance | 24.132 (± 1.408) | − 1.164 (± 0.254) | − 3.371 (± 1.168) | − 1.278 (± 0.626) | 0.91 |
Fluorescence | 22.063 (± 2.121) | − 1.397 (± 0.303) | − 4.127(± 1.690) | − 1.142 (± 0.965) | 0.96 |
Stokes’ shift | 5.069 (± 1.465) | 0.536 (± 0.446) | − 2.563 (± 1.301) | − 1.028 (± 0.812) | 0.86 |
Sunset yellow FCF | |||||
Absorbance | 22.607 (± 1.315) | − 0.474(± 1.251) | − 1.835(± 1.780) | − 0.618 (± 1.761) | 0.94 |
Fluorescence | 29.099 (± 4.092) | − 5.032 (± 1.918) | − 7.769 (± 2.653) | − 1.729 (± 0.832) | 0.83 |
Stokes’ shift | 5.107 (± 0.129) | − 0.446 (± 0.124) | − 1.869 (± 0.140) | − 1.280(± 0.150) | 0.99 |
Tartrazine | |||||
Absorbance | 32.268 (± 3.689) | − 1.426 (± 0.793) | − 6.806 (± 2.866) | − 4.741 (± 1.806) | 0.82 |
Fluorescence | 20.094 (± 0.206) | − 0.468 (± 0.135) | − 1.029 (± 0.210) | − 0.310 (± 0.196) | 0.96 |
Stokes’ shift | 9.172 (± 2.071) | − 0.513 (± 0.384) | − 3.702 (± 1.794) | − 2.566 (± 0.861) | 0.82 |
