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Published on: June 10, 2021
Design and synthesis of a coumarin-based acidichromic colorant
Shih-Lun Lin1, Pei-Yu Kuo, Ding-Yah Yang
1Department of Chemistry and Center for Nanoscience and Technology, Tunghai University, 181, Taichung-Kang Rd. Sec.3, Taichung, Taiwan 407.
Abstract:
This paper describes the fine-tuning of the acidichromic properties of a coumarin-containing colorant 1 by incorporation of electron-donating and electron-withdrawing substituents on the coumarin moiety. Colorant 1 can undergo two distinct and reversible color changes under both strongly acidic and basic conditions, but not in the presence of gaseous ammonia. The results indicated that the bromo-substituted compound 5b changes from red to yellow when exposed to gaseous ammonia, both in solution and on polycarbonate film, suggesting that an electron-withdrawing group at the 7-position of the coumarin moiety made the enolic hydrogen on 5b more susceptible to deprotonation by a base than in the unsubstituted compound 1.
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