Design and synthesis of a coumarin-based acidichromic colorant.
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.
Lin
Shih-Lun
SL
Department of Chemistry and Center for Nanoscience and Technology, Tunghai University, 181, Taichung-Kang Rd. Sec.3, Taichung, Taiwan 407.
Kuo
Pei-Yu
PY
Yang
Ding-Yah
DY
D003116:Color; D004396:Coloring Agents / Q000138:chemical synthesis* / Q000737:chemistry; D003374:Coumarins / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D013056:Spectrophotometry, Ultraviolet; D017186:Titrimetry
D004396:Coloring Agents; D003374:Coumarins; C030123:coumarin