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首页> 外文期刊>Journal of Physical Organic Chemistry >Solvatochromism as an efficient tool to study N,N-dimethylamino- and cyano-substituted π-conjugated molecules with an intramolecular charge-transfer absorption
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Solvatochromism as an efficient tool to study N,N-dimethylamino- and cyano-substituted π-conjugated molecules with an intramolecular charge-transfer absorption

机译：溶剂致变色作为研究分子内电荷转移吸收的N，N-二甲基氨基和氰基取代π共轭分子的有效工具

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摘要

A representative data set has been gained by the measurement of the electronic absorption spectra of 12 systematically selected push-pull systems with an intramolecular charge-transfer (CT) absorption and the general structure D-π-A (D=donor, A=acceptor) featuring electron-withdrawing CN groups, electron-donating N(CH_3)_2 groups, and various π-conjugated backbones in 32 solvents with different polarities. The longest-wavelength absorption maxima λmax and the corresponding wavenumbers ?max were evaluated from the UV/Vis spectra measured in 32 well-selected solvents. The D-π-A push-pull systems were further characterized by quantum-chemical quantities and simple structural parameters. Structure-solvatochromism relationships were evaluated by multidimensional statistic methods. Whereas solvent polarizability and solvent cavity size proved to be the most important factors affecting the position of λmax, the solvent polarity was less important. The most important characteristics of organic CT compounds are the energy of the LUMO, the permanent dipole moment, the COSMO (COnductor-like Screening MOdel) area, the COSMO volume, the number, and ratio of N,N-dimethylamino and cyano groups, and eventually the number of triple bonds (π-linkers). A relation between the first-order polarizability α, the longest-wavelength absorption maxima λmax, and the structural features has also been found. The higher-order polarizabilities β and γ are not related to the observed solvatochromism.
机译：通过测量12种系统选择的具有分子内电荷转移（CT）吸收和一般结构D-π-A的推挽系统的电子吸收光谱，获得了一个代表性的数据集（D =供体，A =受体）在32种极性不同的溶剂中具有吸电子CN基，给电子N（CH_3）_2基和各种π共轭骨架。从在32种精心选择的溶剂中测得的UV / Vis光谱评估最长波长吸收最大值λmax和相应的波数λmax。 D-π-A推挽系统的特征还在于量子化学量和简单的结构参数。结构-溶剂变色关系通过多维统计方法进行评估。事实证明，溶剂极化率和溶剂腔尺寸是影响λmax位置的最重要因素，而溶剂极性则没有那么重要。有机CT化合物最重要的特征是LUMO的能量，永久偶极矩，COSMO（类似导体的屏蔽模型）面积，COSMO体积，N，N-二甲基氨基和氰基的数量和比例，最终是三键（π-接头）的数量。还发现一阶极化率α，最长波长吸收最大值λmax与结构特征之间的关系。高阶极化率β和γ与观察到的溶剂变色无关。

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