Abstract:Attaching 2-thienyl residues to the Pechmann dye core chromophore (5,5-exo-dilactone situated around a C-C double bond) results in a novel magenta-coloured compound (UV/Vis spectroscopy λ(max) =570 nm in CHCl(3)), which can be rearranged to a yellow 6,6-endo-dilactone (λ(max) =462 nm in CHCl(3)). Single and double amidation results in pronounced redshift in the 5,5-exo series (violet, λ(max) =570 nm and blue, λ(max) =606 nm in CHCl(3), respectively) but pronounced blueshift in the 6,6-endo series (yellow, λ(ma… Show more
“…From the Table 3 it can be seen that the obtained results indicate that calculated values of k max obtained by TD-DFT methods are lower than the experimental data. However, despite this deviation, the TD M06-2X method is found to be efficient for evaluating the absorption spectra of conjugated dyes [26,27], and our results are in consistent with this. Also, it is known that this method overestimates energies of electronic transitions [25].…”
Section: Uv-vis Studies and Electronic Propertiessupporting
In this paper, spectroscopic and quantum mechanical investigation of nine 4-aryl-5-arylazo-3-cyano-6hydroxy-2-pyridone dyes was performed, and obtained density functional theory (DFT) results were compared with experimental data. The structural and spectroscopic properties of azo-2-pyridone dyes were studied by DFT using B3LYP, CAM-B3LYP, and M06-2X methods with a 6-311++G(d,p) basis set. Comparison of results reveals that the scaled theoretical vibrational frequencies of azo dyes are in good agreement with experimental data. The time-dependent DFT calculated and experimental ultraviolet-visible (UV-vis) absorption spectra are also in good agreement. The effect of electron-donating -OCH 3 and electronwithdrawing -NO 2 groups on the structural parameters, vibrational frequencies, UV-vis absorption, and natural bond orbital (NBO) atomic charges were thoroughly analysed. Vibrational, UV-vis, and NBO analyses confirm that investigated dyes exist in the hydrazo tautomeric form in the solid state and ethanol solution. These analyses signify the occurrence of intramolecular charge transfer in these azo-pyridone dyes.
“…From the Table 3 it can be seen that the obtained results indicate that calculated values of k max obtained by TD-DFT methods are lower than the experimental data. However, despite this deviation, the TD M06-2X method is found to be efficient for evaluating the absorption spectra of conjugated dyes [26,27], and our results are in consistent with this. Also, it is known that this method overestimates energies of electronic transitions [25].…”
Section: Uv-vis Studies and Electronic Propertiessupporting
In this paper, spectroscopic and quantum mechanical investigation of nine 4-aryl-5-arylazo-3-cyano-6hydroxy-2-pyridone dyes was performed, and obtained density functional theory (DFT) results were compared with experimental data. The structural and spectroscopic properties of azo-2-pyridone dyes were studied by DFT using B3LYP, CAM-B3LYP, and M06-2X methods with a 6-311++G(d,p) basis set. Comparison of results reveals that the scaled theoretical vibrational frequencies of azo dyes are in good agreement with experimental data. The time-dependent DFT calculated and experimental ultraviolet-visible (UV-vis) absorption spectra are also in good agreement. The effect of electron-donating -OCH 3 and electronwithdrawing -NO 2 groups on the structural parameters, vibrational frequencies, UV-vis absorption, and natural bond orbital (NBO) atomic charges were thoroughly analysed. Vibrational, UV-vis, and NBO analyses confirm that investigated dyes exist in the hydrazo tautomeric form in the solid state and ethanol solution. These analyses signify the occurrence of intramolecular charge transfer in these azo-pyridone dyes.
“…However given the status of present day technology it is more attractive to obtain 1,4-butanediol from the reduction of bio-based succinic acid, also a fermentation product [ 4 ]. 1,4-Butanediol is a solvent in its own right [ 143 , 144 , 145 ], although in this regard it receives limited attention compared to its application as a monomer for the plastics market [ 146 , 147 ]. It is obvious that starting from the base chemicals results in is a longer synthesis of THF or NMP than the shortcut provided by fermentation to give the intermediate 1,4-butanediol.…”
The global bio-based chemical market is growing in size and importance. Bio-based solvents such as glycerol and 2-methyltetrahydrofuran are often discussed as important introductions to the conventional repertoire of solvents. However adoption of new innovations by industry is typically slow. Therefore it might be anticipated that neoteric solvent systems (e.g., ionic liquids) will remain niche, while renewable routes to historically established solvents will continue to grow in importance. This review discusses bio-based solvents from the perspective of their production, identifying suitable feedstocks, platform molecules, and relevant product streams for the sustainable manufacturing of conventional solvents.
“…The B3LYP functional has been successfully applied in previous studies investigating the structures, electronic properties and spectral characteristics of dye compounds [9], [12], [18], [19]. Therefore, optimized geometries were obtained for all species at the B3LYP/3-21G(d) and B3LYP/6-31G(d) levels of theory.…”
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