Harada Jun, Fujiwara Toshikatsu, Ogawa Keiichiro
Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro, Tokyo 153-8902, Japan.
J Am Chem Soc. 2007 Dec 26;129(51):16216-21. doi: 10.1021/ja076635g. Epub 2007 Nov 29.
The thermochromism of salicylideneanilines in the solid state has been so far explained only in terms of the temperature-induced change of light absorption, which is caused by the shift of the tautomeric equilibrium between the enol and cis-keto forms. In this study, we measured variable temperature diffuse reflectance and fluorescence spectra of the crystalline powders of salicylideneanilines. We also determined their fluorescence quantum yields. The chromaticity coordinates at each temperature were calculated from these data and compared to the perceived colors of the powders. We found that the temperature-induced shift of the tautomeric equilibrium is not the main cause of the thermochromic color change of the thermochromic crystals and that the thermochromism can be explained only by taking account of the temperature-induced change of fluorescence.
迄今为止，水杨醛苯胺类化合物在固态下的热致变色现象仅从温度诱导的光吸收变化角度进行了解释，这种变化是由烯醇式和顺式酮式之间互变异构平衡的移动引起的。在本研究中，我们测量了水杨醛苯胺类化合物结晶粉末的变温漫反射光谱和荧光光谱。我们还测定了它们的荧光量子产率。根据这些数据计算出每个温度下的色度坐标，并与粉末的感知颜色进行比较。我们发现，互变异构平衡的温度诱导移动不是热致变色晶体热致变色颜色变化的主要原因，热致变色现象只能通过考虑温度诱导的荧光变化来解释。
