Synthesis and evaluation of new thienyl and bithienyl-bis-indolylmethanes as colorimetric sensors for anions

The synthesis and full characterization of new bis-indolylmethanes containing thienyl and bithienyl moieties are reported. The sensor ability of the compounds in the presence of halide ions (F(-) Cl(-), Br(-), and I(-)), NO(3)(-), ClO(4)(-), SO(4)(2-), CN(-), and OH(-) ions was investigated in acetonitrile. The experimental results indicate that they Could act as selective chromogenic-sensing molecules for the most basic anions F(-) CN(-) and OH(-) as a well-defined color change from yellow to pink was observed. The interaction constants between compounds 1 and 2 in the presence of F, CN, and OH(-) were calculated and increased in the order OH(-) > F(-) > CN(-). Copyright (C) 2008 John Wiley & Sons, Ltd.