Design and Synthesis of a Coumarin-based Acidichromic Colorant

Abstract

This paper describes the fine-tuning of the acidichromic properties of a coumarin-containing colorant 1 by incorporation of electron-donating and electronwithdrawing 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.

The Antioxidant Activity of New Coumarin Derivatives

“…Coumarins also have the super thermal stability and outstanding optical properties including extended spectral response, high quantum yields and superior photo stability. Optical applications of these compounds, such as laser dyes, nonlinear optical chromophores, fluorescent whiteners, fluorescent probes, polymer science, optical recording and solar energy collectors have been widely investigated [ 16 – 20 ]. Classical routes to coumarins incorporate Pechmann, Knoevenagel, Perkin, Reformatsky, and Wittig condensation reactions [ 21 – 24 ].…”

The Use of Umbelliferone in the Synthesis of New Heterocyclic Compounds

“…Coumarins also have superior thermal stability and outstanding optical properties, including an extended spectral response, high quantum yields and superior photostability. Optical applications of these compounds, such as laser dyes, nonlinear optical chromophores, fluorescent whiteners, fluorescent probes, polymer science, optical recording and solar energy collectors, have been widely investigated [15,16,17,18,19]. The chemistry of thiosemicarbazones has received considerable attention because of their variable bonding modes, promising biological implications, structural diversity, and ion-sensing ability [20,21,22].…”

Synthesis of Symmetrical Acetophenone Azine Derivatives as Colorimetric and Fluorescent Cyanide Chemosensors

“…However, the addition of NaOH 10% caused the color change from colorless to a very light yellow for compound 1 and yellow for compound 2. The yellow color was obtained because the addition of bases can deprotonate the pH-sensitive groups [21]. Deprotonation of the H atom on hydroxyl group of compound 2 produced phenoxide ion and followed delocalization of electrons.…”