Microwave Assisted Synthesis of Amino-Thiophene Dyes and study ofSolvent Effects on the UV-Visible Absorption Spectra

New series of Amino-thiophene dyes 3 (a-g) were synthesized, With growing environmental concerns, developing greener approach for the synthesis of azo dyes is crucial. In present research we describe microwave (MW)-assisted protocol for rapid access to a variety of amino thiophene-azo dyes by coupling amino-thiophenecarboxylate with aromatic amines. After MW-assisted synthesis , Compounds were isolated by precipitation followed by recrystallization to obtain pure azodyes.Then newly synthesized thiophene dyes gave positive solvatochromism so that the absorption bands of the azodye, move towards longer wavelengths as the polarity of the solvent increases. Color plays a significant role in a wide range of industries particularly in printing, pharmaceutical, cosmetic, food, textile.Azo dyes are considered to be easy to use, relatively cheap and to provide clear, strong colours. In India there are approximately 2000 azo dyes available the market. Most of the Artificial dyes are used in the market .They are classified as Azo, Xanthene, Indigo, Tetrazine, Triphenylmethane etc. They are one of the most widely used chromophores in dye chemistry. Azo compounds are the compounds of both natural and manufactured chemicals that contain at least one azo group (N2) in their structure. The atomic groups connected to the nitrogen atoms might be of any organic class, but the commercially relevant azo compounds, ,Which account for more than half of all commercial dyes, contain the benzene group or its derivatives as the attached groups. Although azo compounds come in a wide variety, pigments, and dyes are the most popular. Bismarck Brown, the first commercial azo dye, was introduced in 1863.[1-4]The field of heterocyclic azo dyes continues to be dynamic, driven by the need for brighter, more durable, and environmentally friendly dyes. The synthesis and application of heterocyclic azo dyes, especially in textiles,offer significant advantages in terms of color brilliance, fastness, and versatility. The development of novel dyes, including those with antimicrobial properties, is evidence of the constant innovation in this field.[5-6] .Azo compounds have broad fields of applications such as, antifungal, antibacterial [4], anti-inflammatory [5], anticancer and antioxidant [6]. Beside of it, it has many other applications like, coloring fiber [7], printing systems [8], photo electronics [9], analytical, polymer additive [10], optical recording [11] and storage [12], light and weather fastness [13] and resistance to solvents and water [14-16]. Most of theAzo dyes showed positive absorption spectra. [17-19]