RESUMEN
Indole and urea based two organic receptors have been synthesized by an easy synthetic process. These two receptors have strong sensitivity and selectivity for several bio-relevant anions. Receptor 1 and 2 were synthesized from indole-2-carboxylic acid and p-anisidine respectively, which are low cost starting materials. Receptor 1 can selectively sense anions like F(-), OAc(-) and H2PO4(-), while receptor 2 can only sense F(-) and H2PO4(-). Both receptors are silent toward anions like Cl(-), Br(-), I(-) and NO3(-). It is the difference in their shape and size which are responsible for different anion sensing. The nature of these host-guest type interactions was analyzed by convenient spectrophotometric techniques like UV-Vis, fluorescence, (1)H NMR, FT-IR studies and also confirmed by electrochemical techniques like cyclic voltammetry studies of the two ligand receptors with convenient anions. Between receptor 1 and 2, receptor 2 was crystallographically characterized also.