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• 金属-有机框架是由金属离子与有机配体通过配位键形成的三维框架材料，是近几十年来配位化学领域中发展较快的新型多功能材料。自上世纪90年代以来，金属-有机框架的研究呈现空前的增长，目前已有大于20000例的金属-有机框架被报道。金属-有机框架可变的金属中心及有机配体使其结构与功能具有多样性。金属中心的选择几乎覆盖了所有金属，包括主族元素、过渡元素和镧系金属。而配体的选择，除了传统的氮杂环和羧酸类配体外，还可以引入一些官能团对其进行修饰，使已获得的金属-有机框架具有特定的功能。

  与传统的无机多孔材料相比，金属-有机框架材料通常具有高孔隙率和大比表面积，尤其是可调节的结构，使其在清洁能源、磁性、荧光、催化、药物传递和生物医学成像等领域都有重要的潜在应用价值。作为十多年来化学研究的重要前沿之一，金属-有机框架正迅速发展成为能源、材料和生命科学交叉领域的研究热点，并极大地促进了各个学科间的相互发展。

  金属-有机框架材料是伴随着人们对新型能源的需求发展起来的，其能够有效地储存氢气、吸附分离二氧化碳等气体，有望解决传统能源带来的日益严峻的环境问题。迄今为止，金属-有机框架材料已被广泛应用于催化领域，除了含有具备催化活性的官能团外，其孔结构还可提供金属或金属氧化物纳米颗粒的成核环境及催化反应的物理空间。金属-有机框架尤其是稀土金属-有机框架也是荧光材料研究中最活跃的前沿领域之一，因其具有稳定性好和毒性低等特点，在光纤通讯、激光系统及生物成像等方面的应用价值也日渐突显。此外，金属-有机框架还可以与石墨烯、聚合物等复合形成新型的复合材料，并可用于重金属的选择性吸附以及蛋白质的提取与分离等，在生物医学领域、药物缓释以及蛋白质调控等方面具有重大的生物学意义。

  本专辑围绕金属-有机框架专题，收录了在相关研究领域具有丰富经验和影响力的团队所撰写的14篇相关综述文章和研究论文。代表性反映了金属-有机框架在气体分离、荧光、磁性、仿生催化、电池等方面的研究进展，希望借助该专刊的出版，能使广大读者更深入地了解金属-有机框架材料的研究现状和研究趋势，进而推动金属-有机框架研究的发展！

  在此，对本专辑的所有作者、审稿人及编辑部工作人员的卓越工作和辛勤付出表示衷心的感谢！

  Metal-organic frameworks(MOFs) are three-dimensional materials formed by coordination bonds between metal ions and organic ligands, which undergone a marked increase in recent years. Since the 1990s, MOFs have shown unprecedented growth, and more than 20000 MOFs have been reported. MOFs are attractive to scientists because of their diverse metal centers and organic ligands. Most metals can be used for the construction of MOFs, including the main group, transition and lanthanide metals. Although the majority of MOFs are based on carboxylate and nitrogen-containing linkers, the introduction of different functional groups into ligands can also provide endless possibilities of MOFs.

  MOFs materials typically have high porosity, specific surface and tunable structure, which not only show exceptionally intriguing structures, but also have important potential applications in clean energy, magnetism, fluorescence, catalysis, drug delivery and biomedical imaging. As an important advance in chemical research, MOFs have rapidly developed in the field of energy, materials and life sciences, and have greatly contributed to the interdisciplinary development of various disciplines.

  One important contribution of MOFs is that it can be effectively used for hydrogen storage and selective adsorption of carbon dioxide and other gases. The occurrence of MOFs also opens up new opportunities for the development of catalyst, multiple catalytic active sites can be incorporated into both metal nodes and organic ligands, the porous structure can also provide appropriate environment for nucleation of metal and metal oxide nanoparticles. MOFs, especially rare earth based MOFs, show both long fluorescent lifetime and low toxicity, is one of the most attractive areas in fluorescent materials research, and can be widely used in optical fiber communication, laser system and biological imaging.

  In addition, MOFs can form novel composites combining with graphene or polymers. MOFs composites show great potentials for selective adsorption of heavy metals and protein extraction and separation, and have significant applications in biomedical, drug release and protein regulation and so on.

  In this metal-organic framework issue, we selected 14 related research progress including reviews and articles involving small molecule separation, fluorescence, magnetism, biomimetic catalysis, and battery performance of MOFs. We hope that readers will have a deep understanding of the current development of MOFs, and find it beneficial to their future research.

  Toward this end, we greatly appreciate the outstanding contribution of all authors, as well as the strenuous efforts from the editorial staff members.

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