Simple, selective, and sensitive colorimetric and ratiometric fluorescence/phosphorescence probes for platinum(ii) based on Salen-type Schiff bases

Abstract

Ratiometric fluorescence/phosphorescence probes for Pt²⁺ based on the fluorescence quenching from the ligand of Salen-type Schiff bases and phosphorescence enhancement from the resulting Pt(II) complexes have been demonstrated. For phosphorescence enhancement, a good linearity (correlation coefficient R² = 0.996, n = 10) was established with detection limit of 11.6 ± 0.2 ppb. The detection limit would be decreased to 2.31 ± 0.03 ppb if degassing was adopted. To the best of our knowledge, this value is one of the most sensitive probes for Pt²⁺. This system also has good selectivity with little interference from Sr²⁺, Sn²⁺, Pb²⁺, Cr³⁺, Mn²⁺, Al³⁺, Fe³⁺, Ce³⁺, Ag⁺, Li⁺, Mg²⁺, Na⁺, Cd²⁺, Cu²⁺, Ca²⁺, Zn²⁺, K⁺, Co²⁺, Ni²⁺, Au³⁺, Ir³⁺, and Pd²⁺. Moreover, this system is suitable for detection of different Pt(II) sources, such as PtCl₂, K₂PtCl₄, Pt(COD)Cl₂ (COD = 1,5-cyclooctadiene), and cis-platin. It potentially provides a new and simple way to detect some useful transition metal ions, such as Cu⁺, Au⁺, Pd²⁺, and Ru²⁺.