A. Takase, S. Sakagami, K. Nonaka
Jul 1, 1993
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Journal
Journal of Raman Spectroscopy
Abstract
Thermochromism of N-(2-hydroxy-4-methoxybenzylidene)-4-nitroaniline (HMBNA) was studied by Raman scattering and infrared absorption. HMBNA is yellow when freshly prepared and deepens to orange–red on heating above the melting point. On cooling at room temperature, the orange–red colour is retained for a few months. The change in colour is explained by the change in the molecular structure as indicated by the vibrational spectra. The spectra show that in the thermochromic coloured state the central group of HMBNA takes the cis-keto amine form.