Solvatochromic fluorophores based on thiophene derivatives for highly-precise water, alcohols and dangerous ions detection

Abstract

In this paper we report on synthesis and sensing properties of novel thiophene derivatives representing typical push-pull molecules with D-π-A structure. As an electron-donating group we used benzothiophene and various positions of cyano and nitro groups as an acceptor moiety. All compounds exhibit profound solvatochromism with prominent emission varying from blue to red, which indicated high sensitivity to environment polarity. Moreover, even trace amounts of protic solvents (like water and alcohols) are able to significantly quench the luminescence, with the detection limit established to 59 ppm in THF. On the other hand, the dicyanovinyl group presented in one of the compounds made it an extremely sensitive colorimetric and fluorescent sensor for cyanide and hydroxide ions, shifting its emission towards shorter wavelengths. The detection limits for CN− and OH− were established as low as 0.0131 μM and 0.0025 μM, respectively, which is one of the lowest limit reported in literature. Highly-precise sensitivity to water, alcohols and dangerous ions put such thiophene derivatives as easy-to-use and fast detector in everyday life.