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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >H-1 NMR Study on the Self-Association of Quinacridone Derivatives in Solution
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H-1 NMR Study on the Self-Association of Quinacridone Derivatives in Solution

机译：H-1 NMR研究喹ac啶酮衍生物在溶液中的自缔合

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摘要

The pi-stacking structures and self-association thermodynamics of N,N'-di(n-alkyl) quinacridone derivatives (n-alkyl QAs) with various substituents on the side aromatic rings and different length of n-alkyl chains are investigated in organic solvents by H-1 NMR spectroscopy. The stacking geometries are built based on both the magnitudes and directions of peak shifts with concentration and solvent polarity. The intermolecular interaction between nitrogen atoms and oxygen atoms dominates the general geometrical preferences of the stacking in which the molecules are face-to-face arranged in a parallel and an antiparallel fashion, respectively. The stacking structures are little affected by the length of the n-alkyl chains but are regulated in an allowed range by the size and properties of the substituents. The association processes of all the n-alkyl QAs are enthalpically favorable at 298 K, while the relative stability of these n-alkyl QAs assemblies is governed mainly by the entropy of the association processes. The introduction of larger substituents and longer n-alkyl chains disfavors the association of the n-alkyl QAs, while the binding of the halogen atoms on the side aromatic rings is favorable to the association. The relative strength of the stacking interaction for the substituted n-alkyl QAs has not obvious correlation with the electron-donating or electron-withdrawing nature of the substituents, while it is well associated to the dispersion energy and repulsive exchange energy. The different entropy-enthalpy compensation of the halogen-substituted n-alkyl QAs from others may suggest different association mechanism for the two types of n-alkyl QAs.
机译：研究了在有机侧链上具有各种取代基和不同长度的N-烷基链的N，N'-二（n-烷基）喹ac啶酮衍生物（n-烷基QA）的pi堆积结构和自缔合热力学H-1 NMR光谱分析溶剂。堆积的几何形状是根据峰移动的大小和方向以及浓度和溶剂极性建立的。氮原子和氧原子之间的分子间相互作用支配了堆叠的一般几何偏好，在堆叠中，分子分别以平行和反平行的方式面对面布置。堆积结构几乎不受正烷基链长度的影响，但是受取代基的大小和性质限制在允许的范围内。所有正烷基QA的缔合过程在298 K时在焓上都是有利的，而这些正烷基QA组装体的相对稳定性主要由缔合过程的熵决定。引入较大的取代基和较长的正烷基链不利于正烷基QAs的缔合，而侧芳环上的卤素原子的结合则有利于缔合。取代的正烷基QA的堆积相互作用的相对强度与取代基的供电子或吸电子性质没有明显的相关性，而与分散能和排斥交换能密切相关。卤素取代的正烷基QA与其他的不同的熵-焓补偿可能暗示两种正烷基QA的缔合机理不同。

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