Smart Lanthanide Metal–Organic Frameworks with Multicolor Luminescence Switching Induced by the Dynamic Adaptive Antenna Effect of Molecular Rotors

In this work, dynamic molecular rotors are used to construct smart lanthanide metal–organic frameworks (Ln‐MOFs) emitters with adaptive antenna effects for the first time. The movement or distortion of the molecular rotors can be easily regulated by temperature changes, thereby inducing a dynamically changing antenna effect that can automatically match different lanthanide ions, achieving cyclic multicolor luminescence switching behavior and extremely complex multiple encryption anti‐counterfeiting technology. In addition, by regulating the doping ratios of Gd(III) and Tb(III) with Eu(III) within the Ln‐MOFs, differentiated energy transfer pathways are discovered, and red light emission very close to the BT.2020 color gamut standard is obtained. Gd0.99Eu0.01‐MOF containing only 1% Eu(III) can show bright red luminescence, and in the range of 1–9% Eu(III) content, the characteristic emission intensity of Eu(III) ions and the content show an excellent linear relationship with a slope k as high as 2299. This can be used to identify the content of Eu(III) ions impurities in gadolinium salts from different manufacturers. Eu/Tb‐MOF showed highly sensitive and visualized smart photoresponse behaviors to specific antibiotics and amino acids, respectively, with detection limits of 3.2/2.7 nM (tetracycline), 1.7/15.5 nM (oxytetracycline), 0.13/0.97 nM (aspartic acid), and 0.26/1.16 nM (glutamic acid).