The residues of tetracycline antibiotics (TCs) have caused serious environmental pollution due to the multi‐field application. In order to rapidly detect TCs, there is an urgent need to design new fluorescence sensor. Herein, a heterometallic metal‐organic framework (HNU‐61) is constructed and used as a fluorescence sensor for detecting the TCs. In HNU‐61, both Zn2+ and Li+ ions are assembled into the crystal structure, in which Zn2+ adopts tetrahedral coordination mode, and can be served as the potential coordination site. The 3D structure of HNU‐61 is formed by the connection between Zn2+/Li+ and isophthalic acid (m‐BDC2−) ligand with the 1D channel along a axis. Among the six categories of antibiotics, HNU‐61 can effectively detect TCs, including tetracycline hydrochloride (TCY), chlortetracycline hydrochloride (CTE), doxycycline hydrochloride (DOX), and oxytetracycline hydrochloride (OXY) with the detection limits of 6.5 × 10−8 M, 9.2 × 10−8 M, 4.5 × 10−7 M, and 3.9 × 10−7 M, respectively. Furthermore, HNU‐61 enables a rapid and sensitive detection of TCs with good anti‐interference and circulation. The detection mechanism can be attributed to the interaction between Zn2+ in HNU‐61 and TCs.

Defect engineering has been generally observed and utilized in crystal materials including metal oxides, metal–organic frameworks, and so on; however, how to relate the defect formation and crystallization process is needed to be revealed clearly, and how to heal the defect is a big challenge. Herein, based on the new coordination complex (HNU-53), the crystal defects were created by increasing the reaction time and crystal size. Following the crystal growth process, the crystal color centers were simultaneously generated, resulting in fluorescence quenching. To heal the defect, the crystal growth was controlled by the introduction of rare earth ions. With the coordination competition of rare earth ions, the crystal defects were reduced and recovery of fluorescence emission was achieved.