Tripodal Cadmium Complex and Macrocyclic Ligand Based Sensors for Phosphate Ion Determination in Environmental Samples

Abstract

AbstractTripodal cadmium complex of hydrotris(3‐phenyl‐5‐methylpyrazolyl)borate (I1) and macrocyclic ligand 5,7 : 12,14 : 19,21 : 26,28‐Bzo4‐[28]‐5,13,19,27‐tetraene‐8,11,22,25‐N4–1,4,15,18‐O4 (I2), have been synthesized and characterized by IR, 1H NMR, Mass and elemental analysis. Spectroscopic investigations indicate high affinity of these receptors for dihydrogen phosphate ion. Polyvinyl chloride (PVC) based membranes of (I1) and (I2) using hexadecyl trimethylammonium bromide (HTAB) as cation discriminator and dibutylpthalate (DBP), tributyl phosphate (TBP), dioctylsebacate (DOS), and o‐nitrophenyloctyl ether (o‐NPOE), as plasticizing solvent mediators were prepared and investigated as H2PO$\rm{ {_{4}^{-}}}$ selective sensors. The best performance was shown by the membrane of composition (w/w) (I2) (5%):PVC (31%) : DBP (61.5%):HTAB (2.5%). This sensor works well over a wide concentration range 2.1×10−7 to 1.0×10−2 M with Nernstian compliance (59.0 mV decade−1 of activity) with a fast response time of 14 s and showed good selectivity for dihydrogen phosphate ion over a number of anions. The sensor exhibits good reproducibility (SD±0.3 mV) and could be used successfully for the determination of phosphate in soil water samples.