Study on High Specific Response of Tetrasulfonyl Nickel Phthalocyanine-Pb(II) Optical Probe to Triphosphate in Aqueous Phase

A series of reactions between cationic ions and nickel tetrasulfonated phthalocyanine (nickel 4,4’,4’,4’-tetrasulfophthalocyanine, NiS 4 Pc) were performed and demonstrated that water-soluble NiS 4 Pc can complex with Pb 2+ to form an insoluble compound, many acid anions can dissolve this compound. However, the presence of acidic materials (acid inhibitors) can inhibit the dissolution of this compound by acid anions. Screening of acid inhibitors led to an important finding. In the presence of a low concentration of citric acid, the precipitate dissolution by most anions was completely or significantly inhibited; only 5 3 10 P O − could still dissolve the precipitate compound, NiS 4 Pc-Pb(II), to release NiS 4 Pc. The solution phase shows the characteristic color and absorption spectroscopy of NiS 4 Pc-Pb(II), thus providing a specific optical probe for 5 3 10 P O − . In addition, the color and absorption intensity of the solution remained stable for a long time (more than three months), indicating significant stability of the optical probe. Based on this finding, a new spectrophotometric technique has been established for detecting and quantifying aqueous