A Systematic Study of Thermochromic Aromatic Donor−Acceptor Materials

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• 作者：Paul M. Alvey ; Joseph J. Reczek ; Vincent Lynch ; Brent L. Iverson
• 刊名：Journal of Organic Chemistry
• 出版年：2010
• 出版时间：November 19, 2010
• 年：2010
• 卷：75
• 期：22
• 页码：7682-7690
• 全文大小：1066K
• 年卷期：v.75,no.22(November 19, 2010)
• ISSN：1520-6904

文摘

Molar mixtures (1:1) of electron-rich dialkoxynapthalene (Dan) and electron-deficient 1,4,5,8-napthalenetetracarboxylic diimide (Ndi) derivatives form highly tunable, columnar mesophases with a dark red color due to a charge transfer absorbance derived from alternating face-centered stacking. Certain Dan−Ndi mixtures undergo a dramatic color change from dark red to an almost colorless material upon crystallizing from the mesophase. Macroscopic morphology of the solid is not changed during this process. In order to investigate the origins of this interesting thermochromic behavior, Dan and Ndi side chains were systematically altered and their 1:1 mixtures were studied. We have previously speculated that the presence or absence of steric interactions due to side chain branching on the aromatic units controlled the level of color change associated with crystallization. Results from the present study further refine this conclusion including a key crystal structure that provides a structural rationale for the observed results.