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

ABSTRACT

The 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, c_PAT = 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.

KEYWORDS:

• UV–vis spectroscopy
• ratiometric and colorimetric sensors
• Pb²⁺ detection
• 4-phenyl amino thiourea

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (Grant Nos. 21671037, 21471030, 21277103, and 21271040).