JACS: progress in coordination and self-assembly of rare earth luminescent supramolecular polyhedrons

Recently, sun Qingfu, a researcher of the State Key Laboratory of structural chemistry, Fujian Institute of material structure, Chinese Academy of Sciences, and Han Keli, a researcher of Dalian Institute of Chemical Physics, Chinese Academy of Sciences, have made progress in the coordination self-assembly and sensing application of lanthanide rare earth luminescent polyhedron For the first time, the team proposed the strategy of combining charge transfer state rare earth sensitization and coordination guided self-assembly in the ligand to construct lanthanide cage type supermolecule with strong fluorescence performance, and successfully prepared the lanthanide supermolecule tetrahedron with the highest luminous quantum yield (Φ = 23.1%) By means of quantitative self-assembly of C3 symmetrical ligand with push-pull electronic structure and europium (Ⅲ) ion with relatively stable 9 coordination configuration, NMR, high-resolution mass spectrometry and synchrotron radiation X-ray single crystal diffraction, the final product was confirmed to be a single ln 4L 4 type rare earth super molecular tetrahedron Different from the traditional triplet energy transfer sensitization path from ligand s 1 → T 1 → LN, the unique singlet rare earth sensitization process of ligand s 1 → ILCT 1 → ln is shown in this supramolecule The sensitization mechanism of the new lanthanide supramolecular system has been directly confirmed by the time-dependent density functional theory calculation and the experimental results of femtosecond transient absorption In addition, based on the sensitivity of charge transfer excited states in ligands to the chemical environment, these supramolecules have the properties of highly selective fluorescent probes with double response of cations and anions without the introduction of additional recognition groups: among them, the fluorescence quenching type i-ion recognition process has the detection sensitivity of ppm level, while for the traditional fluorescence quenching effect Cu2+ Ions show a unique fluorescence enhanced recognition behavior The global fit data of femtosecond transient absorption spectrum show that the mechanism of double responsive ion recognition is closely related to the change of internal conversion quantum efficiency of ligand excited state S1 → ILCT 1 This work provides a new strategy to improve the optical properties of rare earth metal organic polyhedron, and provides an important research idea for the design and development of intelligent molecular based rare earth fluorescent materials in the future Self assembled polyhedral structure (source: J am Chem SOC.) Previously, in view of the complex and variable coordination number and configuration of lanthanide metal ions, which are difficult to control, sun Qingfu's research group adopted strategies such as multi tooth design of coordination sites, chiral induction of ligands, and structural continuity control, etc., in the stereoselective synthesis of rare earth supramolecular polyhedra with specific molecular composition and geometric configuration, the general rule of structural evolution, and nitro group A series of progress has been made in compound fluorescence sensing "2017 top ten science and technology news of China's rare earth", sponsored by China Rare Earth Society, China Rare Earth Information Center and national rare earth information network, and co organized by Information Professional Committee of China Rare Earth Society, was announced, and "coordination self assembly research of rare earth luminescent supermolecular polyhedron of Fujian Institute of architecture, Chinese Academy of Sciences" was selected Paper link: https://pubs.acs.org/doi/10.1021/jacs.7b05157 corresponding author: Sun Qingfu http://www.fjirsm.ac.cn/yjsjy/dsjj/sssds/sqf/hankley http://www.beam.dicp.ac.cn/chinese/members/personalnfo/kelihan.htm