Anion recognition using newly synthesized hydrogen bonding diamide receptors: PVC based sensors for carbonate

Abstract

Novel hydrogen bonding diamide receptors viz., N, N I-bis(phenyl)iso phthalohydrazide ( I) and N, N I-bis(2,4-dinitrophenyl)isophthalohydrazide ( II), have been synthesized and characterized by IR, 1H NMR and elemental analysis. Spectroscopic investigations indicate high affinity of these receptors for carbonate ion. Polyvinyl chloride (PVC) based membranes of ( I) and ( II) using tridodecylmethylammonium chloride (TDDMACl) as cation discriminator and diethylphthalate (DEP), dioctylphthalate (DOP), 1-chloronapthalene (CN), tris(2-ethylhexyl)phosphate (TEHP) and bis(2-ethylhexyl)sebacate (DOS) as plasticizing solvent mediators were prepared and investigated as CO 3 2− selective sensors. The best performance was shown by the membrane of composition (w/w) of ( II) (4%):PVC (33%):CN (60%):TDDMACl (3%). This sensor works well over a wide concentration range 1.3 × 10 −7 to 1.0 × 10 −3 M with Nernstian compliance (29.0 mV decade −1 of activity) at pH 8.6 with a fast response time of ∼7 s and showed good selectivity for carbonate over a number of anions. The sensor exhibits adequate shelf life (two and half months) with good reproducibility (S.D. ± 0.3 mV) and could be used successfully for the determination of total inorganic carbon in water samples.