CAS 130-22-3 Alizarin Red S - Analytical Products / Alfa Chemistry

CAT	APB130223
CAS	130-22-3
Structure
Synonyms	Alizarin Carmine; Alizarin sulfonate sodium; Alizarinsulfonic acid sodium salt, Sodium alizarinsulfonate
Molecular Weight	342.3
Molecular Formula	C14H7NaO7S

Appearance	Reddish powder
Absorption Wavelength	λmax 594-619 nm
Color Index	58005

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Case Study

Alizarin Red S for Crosslinking and Doping in Polypyrrole/Graphene Composite Aerogels

Wang, Quanlu, et al. Journal of Power Sources 517 (2022): 230737.

Alizarin Red S (ARS) has been demonstrated as a multifunctional agent in the synthesis of polypyrrole (PPy)/graphene composite aerogels (PGA) through a one-step hydrothermal method. ARS serves as a crosslinker, oxidant, reductant, and dopant, facilitating the formation of a robust three-dimensional porous network.
In the synthesis process, graphene oxide (GO) aqueous solution was ultrasonicated, followed by the addition of ARS. Pyrrole was then introduced to form a GO-ARS-pyrrole (GO-ARS-Py) assembly via hydrogen bonding and π-π interactions. The mixture was subjected to hydrothermal treatment at 180 °C for 10 hours, resulting in the formation of PGA composites. Atomic force microscopy (AFM) confirmed the increased thickness of GO upon ARS modification (from 2-4 nm to 5-7 nm), supporting the formation of GO-ARS assembly.
ARS played a dual role in oxidation and reduction during the reaction. It facilitated the oxidation of pyrrole to PPy while being reduced to r-ARS. The r-ARS further reduced GO by removing hydroxyl and epoxy groups, subsequently reverting to ARS. Covalent ester bonds were formed between the -OH groups of r-ARS and the -COOH groups of reduced GO (RGO), establishing a physical/chemical double cross-linking network. This enhanced the structural stability and doping efficiency of the composite aerogels.
The multifunctionality of ARS in oxidation, reduction, crosslinking, and doping highlights its critical role in enhancing the electrical conductivity, mechanical strength, and structural integrity of PPy/graphene composite aerogels, making it a promising material for energy storage and sensor applications.

Alizarin Red S for Enhancing the Electrochemical Performance of Carbon Cloth/ZIF67/Polypyrrole Composite Electrodes

Wang, Quanlu, et al. Electrochimica Acta 407 (2022): 139869.

Alizarin Red S (ARS) has demonstrated significant potential as a redox dopant and growth-directing agent in the synthesis of carbon cloth/ZIF67/polypyrrole (CZPA) composite electrodes for supercapacitor applications. The composite was prepared through a two-step process: in-situ growth of ZIF67 on carbon cloth followed by electrochemical polymerization of pyrrole in the presence of ARS.
In the preparation process, 1 mmol of pyrrole was added to an aqueous solution containing LiClO₄·3H₂O and varying concentrations of ARS. The electrochemical polymerization was conducted at 0.5 V for 40 minutes using a three-electrode configuration, with carbon cloth/ZIF67 as the working electrode. ARS played a critical role in facilitating the ordered growth of polypyrrole (PPy) and enhancing doping efficiency.
The surface of activated carbon cloth, rich in oxygen-containing functional groups, coordinated with Co²⁺ ions from ZIF67, resulting in an ordered microsheet-constructed 3D porous structure. ARS formed conjugated interactions and hydrogen bonds with the ligand 2-MeIM, promoting the controlled growth of PPy. Furthermore, ARS acted as a redox dopant, improving the conductivity and electrochemical stability of the composite.
The resulting CZPA composite electrodes exhibited enhanced areal specific capacitance, flexibility, and cycling stability due to the synergistic effects of the porous structure, redox activity, and ordered growth facilitated by ARS. This highlights the multifunctionality of ARS in improving the structural and electrochemical properties of composite electrodes for high-performance supercapacitor applications.

Alizarin Red S for Enhancing the pH-Responsive Properties of Cationic Guar Gum-Carrageenan Blend Packaging Films

Chen, Jiaci, et al. Food Hydrocolloids 156 (2024): 110272.

Alizarin Red S (ARS) has shown promising potential in the development of intelligent food packaging materials with pH-responsive properties. In this study, ARS was incorporated into halochromic cationic guar gum (CGG) and κ-carrageenan (CAR) blend films to create pH-sensitive packaging labels capable of monitoring the freshness of high-protein foods. The ternary ARS-loaded CGG-CAR films were prepared through a simple solution casting and solvent evaporation method.
To fabricate the films, CGG and CAR were blended with polyethylene glycol (PEG-400) in water at 60 °C under continuous stirring. ARS was then added at varying concentrations (0-30 mg/100 mL), and the solution was dried at 40 °C for 48 hours. The resulting films exhibited enhanced mechanical strength, water resistance, and distinct pH responsiveness. The color intensity of ARS at pH 6.0 and 8.0 was significantly different from that at pH 7.0, enabling clear detection of pH variations caused by volatile alkaline compounds released from shrimp and meat spoilage.
The CGG-CAR films, stabilized through hydrogen bonding and electrostatic interactions, maintained consistent structural integrity under neutral pH conditions. ARS acted as both a colorimetric indicator and a structural enhancer, facilitating the formation of a uniform hydrogel matrix when hydrated. This multifunctional behavior positions ARS-loaded CGG-CAR films as effective and responsive indicators for real-time food quality monitoring, thereby contributing to improved food safety and shelf-life assessment.