Synthesis and characterisation of benzothiazole-based solid-state fluorescent azo dyes

• Published in: Coloration technology Vol. 126; no. 6; pp. 348 - 352
• Main Authors: Kasture, Prakhar P, Sonawane, Yogesh A, Rajule, Rajkumar N, Shankarling, Ganapati S
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.12.2010
• Subjects: Azo dyes; Dyes; Fluorescence; Fluorescent dyes; Polyester resins; Solvents; Thermogravimetric analysis; Ultraviolet
• ISSN: 1472-3581; 1478-4408
• DOI: 10.1111/j.1478-4408.2010.00268.x

Novel solid‐state fluorescent azo dyes containing a 2‐[4‐(dimethylamino)phenyl]benzo[d]thiazol‐6‐amine as the electron donor group were synthesised. These dyes showed a molar extinction coefficient in the range of 20 000–30 000 l/mol/cm. These compounds were characterised by strong solid‐state fluorescence under long ultraviolet light (365 nm). Absorption and fluorescence spectra revealed that electron coupling originating from broad π‐electron delocalisation and the keto–enol form is responsible for the large Stokes shift. These dyes were readily soluble in common solvents such as dichloromethane, chloroform, dimethyl formamide, tetrahydrofuran and dimethyl sulphoxide and were characterised by means of elemental analysis, proton nuclear magnetic resonance and mass spectrometry. Thermogravimetric analysis of solid‐state fluorescent dyes show thermal stability up to 270 °C and can therefore be used for polymer application. The coloristic properties of these dyes were evaluated on polyester by the disperse dyeing method.