Remote Control of Near Infrared Emission with Lanthanide Complexes

Abstract Molecular luminescent switches form a unique and fascinating class of compounds whose luminescence response can be toggled with chemical or physical stimuli. Switchable near‐infrared (NIR) emitters are of major interest since they are compatible with in vivo imaging and have potential for advanced materials such as security tags. Of particular interest are the NIR emitting lanthanides, which feature narrow, sharp and intense emission lines originating from the f – f Laporte forbidden transitions. Although, these “fingerprints” are in general rather insensitive to surrounding media, they can be manipulated thanks to a proper engineering of the complex first or second coordination spheres. The resulting switching systems may thus find usefulness in various application fields. In this review, we selected representative examples of switchable lanthanide NIR emitters based on the most relevant stimuli, such as chemical, environmental, thermal, electrochemical and photochemical inputs.