A dual-function luminescent probe for copper(II) ions and pH detection based on ruthenium(II) complex

Abstract

A new ruthenium complex-based luminescent probe Ru-impa for Cu²⁺ and pH detection has been synthesized and characterized. Ru-impa could rapidly and selectively detect Cu²⁺ in aqueous solutions and the working pH ranges from weakly acidic to alkaline. The detection limit calculated using the S/N and S/B ratio was 24.7 nM and 3.4 μM, respectively. The test strips for practical detecting application were also prepared and the actual detection limit in drinking water was found to be 3 μM, which is lower than the WHO-guided drinking water limit (30 µM) and the upper limit of human serum free copper content (1.7-3.9 μM). Luminescence imaging study showed that Ru-impa could monitor Cu²⁺ level fluctuation in the cells. In addition, Ru-impa also shows a sensitive on-off luminescence response when pH > 10, indicating that it can also be used as a pH sensor under extremely alkaline conditions.

Keywords: Copper(II) ion; Luminescent probe; Ruthenium(II) complex; pH-sensor.