Facile synthesis of new coumarin-based colorimetric and fluorescent chemosensors: Highly efficient and selective detection of Pd2+ in aqueous solutions

- A new type of coumarin derivative has been designed and easily prepared.
- The fluorescence sensor exhibits excellent sensitivity and selectivity for Pd2+.
- The sensing process is based on the ICT fluorescence quenching mechanism.
- The detection can also be performed in a visualized manner.

Based on the intramolecular charge transfer (ICT) fluorescence quenching mechanism, a ready-to-use colorimetric coumarin coordinative probe has been designed and successfully achieved for the efficient detection of Pd2+ in aqueous buffer media (pH 7.0), which promisingly meets real-world challenges through a facile synthetic route, fast response, by-eye visualization, regenerative-action, high selectivity and sensitivity. The UV-vis spectra, mass spectra and density function theory studies have indicated that a 1:1 complex is formed between the probe and Pd2+. The detection limit of Pd2+ is up to 2.9 × 10−7 M. This reagent could even be used for estimation of Pd2+ in samples with its known concentrations with considerable accuracy (ca. 4.1-4.8% error). Moreover, the binding affinity and fluorescence quenching degree of 1 with Pd2+ are superior to those of 2. It has been demonstrated that the sensitive property of the chemosensors for Pd2+ is highly dependent on the fine structure of the conjugated compounds.

Based on the ICT fluorescence quenching mechanism, a new type of coumarin derivative has been successfully achieved as an efficient colorimetric and fluorescent sensor for Pd2+ in aqueous solutions.65