Thiourea and amidothiourea moieties are among the most widely used –NH donor binding subunits for anion coordination and sensing. To advance this research, we report the synthesis of colorimetric thiourea and amidothiourea based receptors, derived from isoniazid and other scaffolds, and their anion sensing studies using UV-vis, Fluorescence and 1H NMR spectroscopies. Selective detection of strongly basic anions, such as CN-, F-, OAc- and OBz-, resulted in concomitant color change due to deprotonation. However, weakly basic anions, such as Br-, Cl-, HSO4-, N3- , ClO4- and NO3-, did not show any significant color change. The use of 1H NMR titrations further demonstrated deprotonation of the more acidic –NH protons, resulting in subsequent intramodular charge transfer responsible for the observed color changes. Such colorimetric sensors have great potential applications in the field as naked-eye sensors.

Synthesis and studies of thiourea and amidothiourea based anion sensing receptors

255th National Meeting (2018)

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