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首页> 外文期刊>Bulletin of the Chemical Society of Japan >Theoretical Study on Acylacetanilide Azomethine Dyes:A Relationship between Electronic Absorption Properties and Molecular Structures
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Theoretical Study on Acylacetanilide Azomethine Dyes:A Relationship between Electronic Absorption Properties and Molecular Structures

机译：酰基乙酰苯胺甲亚胺染料的理论研究：电子吸收性质与分子结构的关系

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摘要

The relationship between visual absorption properties and molecular structures was investigated for a series of yellow azomethine dyes derived from 4-diethylamino-2-methylaniline and 2-acyl-2'-chloroacetanilides,in which the acyl groups are 1-indolinylcarbonyl(IA),1-methylcyclopropylcarbonyl(CA),acetyl,benzoyl,and pivaloyl(PA).DFT calculations predicted major conformational isomers attributed to deviations from the planarity of the p-aminophenyl-azo-methine fragment.Observed wavelengths were well reproduced by TD-DFT calculations at global minimum geometries,whereas the intensities correlate with the Boltzmann-weighted oscillator strengths.The observed intensities varied by 1.5 times from minimum to maximum without significant shifts in the peak wavelengths,demonstrating the largest absorption of IA and the distinct increase of absorption by changing the acyl group from open-(PA)to closed-ring(CA).The different acyl groups nearly perpendicular to the azomethine fragment in global minima alter frontier orbital energies,while leaving HOMO-LUMO energy gaps almost unchanged.The acyl groups,which are twisted largely in local minima,exert mesomeric effects to lower the LUMO energies.The planarity of the p-aminophenyl-azomethine fragment affects HOMO-LUMO overlapping,but hardly changes HOMO and LUMO energies.These electronic and steric effects rationalize the absorption intensities and peak wavelengths observed for the dyes and also the sharp-cut curves of spectra in the long-wavelength sides for IA and CA.
机译：研究了由4-二乙基氨基-2-甲基苯胺和2-酰基-2'-氯乙酰苯胺衍生的一系列黄色偶氮甲胺染料的视觉吸收性能与分子结构之间的关系，其中酰基为1-indolinyl羰基（IA）， 1-甲基环丙基羰基（CA），乙酰基，苯甲酰基和新戊酰（PA）.DFT计算预测了主要构象异构体，归因于对氨基苯基-偶氮-次甲基片段的平面度偏差.TD-DFT计算可很好地再现观察到的波长强度与玻尔兹曼加权振荡器强度相关。观察到的强度从最小值到最大值变化了1.5倍，而峰值波长没有明显变化，这表明IA的最大吸收和通过改变而明显增加的吸收从开环（PA）到闭环（CA）的酰基基团。改变边界轨道的能量，而保持HOMO-LUMO的能隙几乎不变。在局部极小值处扭曲的酰基基团具有介观的作用，以降低LUMO的能量。对氨基苯基-偶氮甲胺片段的平面性影响HOMO- LUMO重叠，但几乎不改变HOMO和LUMO能量。这些电子效应和空间效应使染料的吸收强度和峰值波长合理化，并且使IA和CA的长波侧光谱的光谱曲线清晰。

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