Dual-functional ratiometric fluorescent sensor based on mixed-lanthanide metal-organic frameworks for the detection of trace water and temperature

Rapid-response ratiometric sensors are promising tools to detect trace water and temperature. However, achieving an accurately visualized water assay in a very narrow range is still a challenge. Herein, a novel dual-functional ratiometric luminescent sensor, i.e., Eu2.2Tb97.8-TCA, was successfully fabricated based on lanthanide metal-organic frameworks. This sensor showed a very fast (less than 20 s) and relatively ultrasensitive (limit of detection 0.016% v/v) response to trace water in ethanol, achieving the sensitive visual determination of water in ethanol with multiple readouts. Intriguingly, visual and quantitative determination of water with a detection limit of 0.035% v/v was achieved based on the ratio of green (G) to red (R) values combined with a smartphone color picker application (APP). The mechanism has also been proposed based on experimental and theoretical evaluation. Furthermore, Eu2.2Tb97.8-TCA could monitor temperature in the range of 300 to 380 K with an excellent linear relationship, high accuracy and good recyclability. This material could also be tuned to emit white luminescence and hence can be used as a single-phase UV phosphor. The present work provides a novel Ln-MOF with powerful capabilities to detect trace water and monitor temperature, which paves a way for the rational design and synthesis of multifunctional materials.

Automated summary

A novel dual-functional ratiometric luminescent sensor, Eu2.2Tb97.8-TCA, was successfully fabricated for rapid and ultrasensitive detection of trace water in ethanol. The sensor achieved sensitive visual determination of water in ethanol with multiple readouts and could also monitor temperature with high accuracy and good recyclability. This material has potential applications in the design and synthesis of multifunctional materials.