**1. Introduction**

The lanthanide (Ln) family, due to the features of the electron shell, forms a large number of complexes with a set of luminescent properties that is unique among all non-radioactive elements of the Periodic Table. The lanthanide compounds combine effective luminescence in the UV, visible, or near-IR ranges with narrow spectral lines and constant wavelengths. In addition, in the case of lanthanides, it is especially convenient to drive and control luminescence, which opens the way to the creation of new emerging technologies in a chemical sensorics. In the accompanying paper, we have described the principle of luminescence materials with turn-off sensory response, and here we complete our work by proponing both "turn on" and "ratiometric" sensors. This manuscript also concentrates on the role of elements of the Lanthanide Series in this emerging technology.
