A chloride-anion insensitive colorimetric chemosensor for trinitrobenzene and picric acid

A new receptor, the bisTTF-calix[2]thiophene[2]pyrrole derivative 3, has been prepared from the Lewis acid-catalyzed condensation of 2,5-bis(1-hydroxymethylethyl)thiopheno-TTF and pyrrole. This new system is found to form complexes with the electron-deficient guests, trinitrobenzene (TNB) and picric acid (PA), which serve as models for nitroaromatic explosives. The binding phenomenon, which has been studied in organic solution using proton nuclear magnetic resonance and absorption spectroscopies, results in an easy-to-visualize color change in chloroform that is independent of the presence of chloride anion, a known interferant for an earlier tetrakisTTF-calix[4]pyrrole TNB chemosensor. Support for the proposed binding mode comes from a preliminary solid state structure of the complex formed from TNB, namely TNB⊂3. A color change is also observed when dichloromethane solutions of chemosensor 3 are added to solvent-free samples of TNB, PA, and 2,4,6-trinitrotoluene supported on silica gel. Figure A new bis-tetrathiafulvalene calix[2]thiophene[2]pyrrole derivative has been prepared that gives rise to an easy-to-visualize color change in the presence of the model nitroaromatic explosives trinitrobenzene and picric acid. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.

Jonathan L. Sessler (Corresponding author)Email: