Azo-hydrazone tautomerism in a simple coumarin azo dye and its contribution to the naked-eye detection of Cu2+ and other potential applications

Ngororabanga, Jean Marie Vianney; Dembaremba, Tendai O.; Mama, Neliswa; Tshentu, Zenixole R.

doi:10.1016/j.saa.2022.122202

Cited by 4 publications

(2 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Though azo dyes are widely used in various applications, such as dying, medicine, cosmetics, paints, inks, and foods, few studies have focused on their halochromic properties for cost-effective pH sensing in practical applications. [20][21][22] One of the reasons is accounted to be the low stability of azo dyes when exposed to alteration in temperature, pH, light, etc. [23] The dye's chemical, photolytic, and microbial stability are crucial for its value and to extend product shelf life.…”

Section: Introductionmentioning

confidence: 99%

“…Current spoilage detection methods require sophisticated equipment, lab facilities and are time‐consuming which are often costly. Though azo dyes are widely used in various applications, such as dying, medicine, cosmetics, paints, inks, and foods, few studies have focused on their halochromic properties for cost‐effective pH sensing in practical applications [20–22] . One of the reasons is accounted to be the low stability of azo dyes when exposed to alteration in temperature, pH, light, etc [23] .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Unraveling Halochromism of Azo‐Based Sulphonamide and Its Real‐World Applications: A Combined Experimental and Theoretical Approach

Joshi,

Ganorkar

et al. 2023

ChemistrySelect

View full text Add to dashboard Cite

Halochromic azo dyes have versatile applications, including sensing and anti‐counterfeiting, due to their reversible color‐changing properties. In this work we investigated the structure‐dependent halochromism of azo compound (E)‐4‐((2‐hydroxynaphthalen‐1‐yl)diazenyl)benzenesulfonamide (HDBS) and explore its potential applications using experimental and theoretical approaches. Different spectroscopic techniques confirm the structural change in the dye as a consequence of tautomerism reaction upon changing pH (7 to 13). The stable form of hydrazone is isolated and characterized. Based on the spectroscopic characterization, it is concluded that the azo form exists at pH ≤ 9, whereas the hydrazone form at highly alkaline pH. To understand the origin of the absorption peaks, the stability, and tautomerism in water, DFT and TD‐DFT calculations are performed. A reasonable agreement between the theoretical and experimental observations enabled us to unravel the structure‐dependent halochromism. Further, we have shown that HDBS‐coated paper can be a real‐time visual sensor to monitor fish freshness and for anti‐counterfeiting ink. It changes colors with pH shifts, alerts consumers about the status of food. Additionally, erasable paper strip reduces paper waste and chemical pollution. The findings presented in this work provide a promising avenue for the development of halochromic azo compounds with potential applications in sensing and anti‐counterfeiting.

show abstract