**Abstract**

This review aims at describing the possible use of lanthanide coordination compounds as materials for luminescent sensors now more necessary due to the continuous requirements from the society of electroluminescent and lighting devices, for example analytical sensors and imaging instruments. This is the first part of a work describing the photophysical foundations of the luminescence of complex compounds of lanthanides in the context of design materials with a sensory response, and also considers in detail materials with the most common type of response - *turn off* sensors.

**Keywords:** lanthanides, coordination compounds, luminescence, sensors, sensory response mechanism, turn off sensors
