Solvent Effects on the UV-visible Absorption Spectra of some New Thienylazo-thiazole and Thienylazo-thiophene Dyes

Abstract

F ACILE synthesis of various thienylazo-thiazole and thienylazo-thiophene dyes were described. 2-Amino-5-(2-thienylazo)-thiazole dyes 5 and 6 have been constructed by coupling the diazotized 2-aminothiophenes 1a and/or 1b with 2-amino-4-phenylthiazole (3) and/or 2-(N-methylamino)-4-phenylthiazole (4). Coupling of 2-aminothiophene derivative 1a with 2-acetyl-3-oxo-N-phenylbutanethioamide (7) affected cleavage of one acetyl group to furnish the corresponding 2-acetyl-2-thienylazo-thioacetanilide dye 8 which has been utilized as a precursor for the construction of different 3-methyl-2-substituted-4-thienylazo-thiophenes 10-13 through its treatment with the appropriate alpha-chlorinated reagents (namely; MeCOCH 2 Cl, PhCOCH 2 Cl, ClCH 2 COOEt and ClCH 2 CN). The effect of solvent polarity on absorption spectra was investigated, as was the relationship between dye structures and absorption in the UV-visible region.

Synthesis of new heterocycles festooned with thiophene and evaluating their antioxidant activity

“…Depending on the significant pharmacological interests mainly antioxidant activity of substituted thiophenes, there is a strong inspiration for the continuous synthesis of new heterocyclic systems incorporating substituted thiophene moiety. Therefore, further continuation of our previous work, [ 30–34 ] we are informing here the synthesis of some more analogs of various heterocyclic systems (namely; imidazo‐thiazole, imidazo‐tetrazole, imidazo‐triazole, imidazo‐pyridine, imidazo‐imidazole, thiazole and/or thiophene) incorporating 2‐thienyl moiety and evaluating their in vitro anti‐oxidant activity.…”