An MOF-Based Luminescent Sensor Array for Pattern Recognition and Quantification of Metal Ions

The development of a convenient method for the discrimination of typically quenching metal ions such as Cu2+, Co2+, Ni2+, and Fe3+ is of great interest but still a challenge. By simultaneously incorporating Eu3+ and organic dye 3,3 '-diethyloxacarbocyanine iodide (DOC) into a metal-organic framework, MOF-253, a luminescent sensor array MOF-253 superset of Eu3++DOC with three emission centers is generated. Utilizing the diversity of quenching responses of metal ions to the different emission centers, five metal ions including Ag+, Cu2+, Fe3+, Co2+ and Ni2+ can be well distinguished with a discrimination accuracy of 100% at a concentration as low as 60 mu m. Subsequently, the binary and ternary mixtures of three metal ions (Fe3+, Co2+, and Ni2+) can also be discriminated successfully. Furthermore, taking Cu2+ and Ag+ as examples, this MOF-based sensor array can quantify the ion concentration at a low range from 0 to 15 mu m. Most probably, this is the first case of simultaneous recognition and quantitation of metal ions in an aqueous solution using an MOF-based luminescent sensor array. Since a variety of luminescent species including organic dyes and lanthanide ions can be introduced into MOFs to generate multiple-dimensional luminescence, such strategy will open a new avenue for luminescent sensor assays.

Automated summary

The development of a method for discriminating typically quenching metal ions has been a great interest and challenge. By incorporating Eu3+ and DOC into MOF-253, a luminescent sensor array can successfully distinguish various metal ions with high accuracy at low concentrations, and this strategy could open up new possibilities for luminescent sensor assays.