羧酸类金属有机框架

羧酸类金属有机框架是以羧酸根为配体的金属有机框架（MOF），其中，MOF-5、HKUST-1等MOF较为出名。它们可用于吸附、催化等领域。

合成与性质

羧酸类MOF可直接以金属盐和相应的羧酸为原料，在合适的调节剂（酸、碱、辅助配体等）及适当的溶剂中进行合成。水热法和溶剂扩散法是常用的合成方法。^[1]

三价金属（如Fe³⁺、Al³⁺、Cr³⁺）的MOF比二价金属的MOF更具有化学稳定性。^[1]一些无法通过直接反应得到的低价MOF可以借助于金属交换反应来制备，例如，将MOF-5浸泡在VCl₂(py)₄、CrCl₂、MnCl₂、Fe(BF₄)₂·6H₂O的饱和二甲基甲酰胺溶液中，可以得到相应金属部分取代的M-MOF-5（M=V, Cr, Mn, Fe）。^[2]二价金属MOF的金属交换反应遵循Irving-Williams序列（英语：Irving–Williams series），即稳定性高的金属离子可以取代稳定性较差的金属离子。^[3]这一序列为：^[4]

Pd²⁺ > Cu²⁺ > Ni²⁺ > Co²⁺ > Zn²⁺ > Cd²⁺ > Fe²⁺ > Mn²⁺ > Mg²⁺

常见的羧酸MOF

以羧酸根为配体的金属有机框架
MOF种类	结构式	有机配体
MOF-5	Zn₄O(BDC)₃	对苯二甲酸根
HKUST-1	Cu₃(BTC)₂	均苯三甲酸根
CAU-26^[5]	Zr₆O₄(OH)₄(OAc)₆(BDC)₃	对苯二甲酸根
CAU-27^[5]	Zr₅O₄(OH)₄(OAc)₄(BDC)₂	对苯二甲酸根
UiO-66	Zr₆O₄(OH)₄(BDC)₆	对苯二甲酸根

参考文献

^ ^1.0 ^1.1 Thais Grancha; et al. Postsynthetic Improvement of the Physical Properties in a Metal–Organic Framework through a Single Crystal to Single Crystal Transmetallation. Angew Chem Int Ed, 2015. 54 (22): 6521-6525. doi:10.1002/anie.201501691.
^ Carl K. Brozek; Mircea Dincă. Ti³⁺-, V^2+/3+-, Cr^2+/3+-, Mn²⁺-, and Fe²⁺-Substituted MOF-5 and Redox Reactivity in Cr- and Fe-MOF-5. J. Am. Chem. Soc. 2013, 135, 34, 12886–12891. doi:10.1021/ja4064475.
^ Sathish Kumar Kurapati. Transmetalation: A Post-synthetic Modification Tool for Functional Metal–Organic Framework Materials. Springer, 2023. doi:10.1007/978-981-19-5347-7_2.
^ Irving, H.; Williams, R. Order of Stability of Metal Complexes. Nature. 1948, 162: 746–747. doi:10.1038/162746a0.
^ ^5.0 ^5.1 Sebastian Leubner; et al. Expanding the Variety of Zirconium-based Inorganic Building Units for Metal–Organic Frameworks. Angew Chem Int Ed, 2019. 58 (32): 10995-11000. doi:10.1002/anie.201905456.

[Thais-1] 1.0 ^1.1 Thais Grancha; et al. Postsynthetic Improvement of the Physical Properties in a Metal–Organic Framework through a Single Crystal to Single Crystal Transmetallation. Angew Chem Int Ed, 2015. 54 (22): 6521-6525. doi:10.1002/anie.201501691.

[2] Carl K. Brozek; Mircea Dincă. Ti³⁺-, V^2+/3+-, Cr^2+/3+-, Mn²⁺-, and Fe²⁺-Substituted MOF-5 and Redox Reactivity in Cr- and Fe-MOF-5. J. Am. Chem. Soc. 2013, 135, 34, 12886–12891. doi:10.1021/ja4064475.

[3] Sathish Kumar Kurapati. Transmetalation: A Post-synthetic Modification Tool for Functional Metal–Organic Framework Materials. Springer, 2023. doi:10.1007/978-981-19-5347-7_2.

[4] Irving, H.; Williams, R. Order of Stability of Metal Complexes. Nature. 1948, 162: 746–747. doi:10.1038/162746a0.

[CAU-5] 5.0 ^5.1 Sebastian Leubner; et al. Expanding the Variety of Zirconium-based Inorganic Building Units for Metal–Organic Frameworks. Angew Chem Int Ed, 2019. 58 (32): 10995-11000. doi:10.1002/anie.201905456.

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