Kamlet-Taft and Catalan Studies of Some Novel Y-Shaped Imidazole Derivatives |
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Authors: | J Jayabharathi V Thanikachalam K Brindha Devi M Venkatesh Perumal |
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Institution: | (1) Department of Chemistry, Annamalai University, Annamalainagar, 608 002 Tamilnadu, India |
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Abstract: | Some novel Y-shaped imidazole derivatives were developed and characterized by NMR and mass spectral techniques. The photophysical
properties of these imidazole derivatives were studied in several solvents. The Kamlet-Taft and Catalan’s solvent scales were
found to be the most suitable for describing the solvatochromic shifts of the absorption and fluorescence emission. The adjusted
coefficient representing the electron releasing ability or basicity of the solvent, C
β
or C
SB has a negative value, suggesting that the absorption and fluorescence bands shift to lower energies with the increasing electron-donating
ability of the solvent. This effect can be interpreted in terms of the stabilization of the resonance structures of the chromophore.
The observed lower fluorescence quantum yield may be due to an increase in the non-radiative deactivation rate constant. This
is attributed to the loss of planarity in the excited state provided by the non co-planarity of the cinnamaldehyde ring attached
to C(2) atom of the imidazole ring. Such a geometrical change in the excited state leads to an important Stokes shift, reducing
the reabsorption and reemission effects in the detected emission in highly concentrated solutions. |
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Keywords: | |
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