A novel 4-phenyl amino thiourea derivative designed for real-time ratiometric–colorimetric detection of toxic Pb2+

Abstract

ABSTRACTThe objective of this study was to develop a ratiometric and colorimetric organic sensor for Pb2+ detection in environmental samples. A new probe 4-phenyl amino thiourea (PAT) was designed and synthesized using hydrazine hydrate and phenyl isothiocyanate as raw materials. After its structure was characterized and confirmed, its UV–vis spectral property was investigated in detail. PAT possesses a specifically real-time, ratiometric and colorimetric response to Pb2+ in dimethyl formamide (DMF)/H2O (v/v = 9:1, pH = 7.0) within 18.0 s. There was little interference in the presence of some other common metal ions, such as Fe3+, Cd2+, Zn2+, Mg2+, Cr3+, Ca2+, Ba2+, Sn2+, Na+, Mn2+, Hg2+, and Pb2+. Under the optimized conditions (DMF/H2O with v/v of 9:1, cPAT = 1.0 × 10−3 mol·L−1, pH = 7.0), the present sensor PAT was successfully applied for Pb2+ determination in environmental water samples with satisfied recoveries (83.0%–106.0%) and analytical precision (≤7.2%). The recognition mechanism was confirmed to form a stable 1:1 six-member ring complex between the target dye and Pb2+ with a coordination constant of 4.96 × 104.