THEORETICAL AND EXPERIMENTAL STUDIES OF INDOANILINE DYES - A NOVEL RELATIONSHIP BETWEEN ABSORPTION-SPECTRA AND MOLECULAR-STRUCTURE
THEORETICAL AND EXPERIMENTAL STUDIES OF INDOANILINE DYES - A NOVEL RELATIONSHIP BETWEEN ABSORPTION-SPECTRA AND MOLECULAR-STRUCTURE
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DOI：
10.1021/ja00063a059
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发表时间：
1993-05-19
影响因子：
15
通讯作者：
NAKAMURA, S
中科院分区：
文献类型：
--
作者：
ADACHI, M;MURATA, Y;NAKAMURA, S
吲哚苯胺染料的最长吸收带取决于醌环和苯胺环之间的二面角。随着二面角（18°~ 90°）的增大，吸收向更长的波长转移，吸收强度随着平面度的损失而降低。这种波长变化与普遍接受的概念不一致，即分子越平面，红移越大，因为增加了π共轭。在实验结果的基础上，用INDO/S和AM1方法对这种新的光谱变化进行了检测。这种变化不能用HOMO-LUMO的能隙来解释。构型相互作用起着至关重要的作用，其中亚氮原子孤对到LUMO的跃迁尤为重要。得到了吸收光谱与结构之间的关系。这很好地再现了观察到的吲哚苯胺染料的光谱和x射线结构。讨论了二面角相关波长位移的详细特征，重点讨论了结构变化引起的构型混合的重要作用。在这些发现的基础上，可以通过调整取代基来改变吸收光谱的二面角，例如引入大块取代基或分子内氢键。目前的分析扩展了现有的长波吸收概念（通过大π共轭），并为功能染料的设计提供了新的指导原则。该原理不限于目前的染料系列，而可适用于具有非平面结构的广泛范围的染料。
The longest absorption band of indoaniline dyes depends on the dihedral angle between the quinone and the aniline rings. The absorption shifts to longer wavelength and the absorption intensity decreases upon increasing the dihedral angle (18-degrees --> 90-degrees) with the loss of planarity. This wavelength change is not consistent with the generally accepted concept that the more planar the molecule, the larger the red shift because of the increased pi-conjugation. The novel spectrum change has been examined by INDO/S and AM1 methods on the basis of experimental results. The change cannot be explained by the HOMO-LUMO energy gap. The configuration interaction plays an essential role, and the imino N atom lone pair to LUMO transition is especially involved. The relationship between the absorption spectrum and the structure has been obtained. This reproduces well the observed spectra and X-ray structure of indoaniline dyes. The detailed features of the dihedral angle dependent wavelength shift have been discussed focusing on the essential role of configuration mixing induced by the structural change. On the basis of these findings, the altering of the dihedral angle for the tuning of the absorption spectrum can be achieved by adjusting substituents, such as the introduction of a bulky substituent or an intramolecular hydrogen bond. The current analysis extends the existing concept for long wavelength absorption (by large pi-conjugation) and provides a new guiding principle for the design of functional dyes. The principle is not limited to the present series of dyes but can be applicable to a wide range of dyes having a nonplanar structure.