Structurally simple dipodalazo linked salicylaldimine as colorimetric sensor for F- and AcO- ion recognition

摘要

A dipodal.N,N'-bis[4-(benzeneazo)salicylaldehyde)-o-phenylenediamine (receptor 1) has been synthesized and characterized using IR, H-1 and C-13 NMR and mass spectroscopic techniques. The anion recognition properties of receptor 1 is investigated using colorimetric, UV-Vis and fluorescence spectroscopic techniques which shows remarkable color and optical changes for only F- and AcO- ions over other anions such as Cl-, Br-, H2PO4- and OH-. In presence of F- and AcO- ions, slight yellow colored solution of receptor 1 is turned into intense yellow color. Also, addition of F- and AcO- ions to receptor 1 induces the simultaneous decrease and increase in the intensity of absorption band at 345 nm and 455 nm. Further H-1 NMR titration experiment reveals that F ion deprotonates the phenolic OH present in receptor 1 resulting in the formation of HF2- complex. Receptor 1 showed binding constant values of 7.44x10(3) and 5.78x10(3) respectively, and detection limit in the concentration of subnanomolar and micromolar level towards F- and AcO- ions. Finally, receptor 1 has been utilized for the detection of fluoride present in tooth paste and mouthwash in aqueous phase.