Lanthanide complex entrapment for ratiometric luminescent pH and metal ion detection in solution and on film

Detection of pH value and metal ions is highly desirable for environment and many life forms. Most of those reported so far, however, are susceptible to many factors in view of being constituted on a single emissive transition. Herein, we develop a simple ratiometric detector based on Eu3+/Tb3+-complex co-doped Laponite (Eu1Tb1(DPA)n@Lap (n ≈ 0.6). Such a detector can simultaneously achieve rapid detection for pH value and an identification of metal ions (Cu2+, Al3+, Bi3+, Ni2+, Fe3+, Ce3+ or Co2+) and these metal ions concentration by a combination of chromaticity and intensity changes of the luminescence. In addition, this detector can accomplish a fingerprint correlation between pH (or metal ions) and emission intensity ratio (IEu/ITb). It is also shown that thin films achieved by drop casting maintain the rapid sensor functions of the bulk material. The overall approach should be a very promising strategy to achieve detecting applications.