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Figure 12. (A and B) Illustration of pore space partition through symmetry-matching regulated ligand insertion; (C-F) Gas sorption
study on compounds CPM-33a and CPM -33b. Reproduced with permission from Zhao et al. [120] . Copyright 2015 American Chemical
Society.

provides a new idea for MOFs to improve gas adsorption performance and is expected to achieve greater
breakthroughs in fuel molecule adsorption.

Other functionalization
In addition to these common CO capture strategies, scientists have also explored other ways to efficiently
2
capture CO . In a typical Langmuir-type isotherm, bulk CO adsorbents cannot be regenerated during
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desorption because the adsorption gain decreases with increasing temperatures. Instead, adsorbents with S-
shaped CO isotherms are preferable. Some flexible MOFs can display such S-shaped CO equivalent due to
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the structural switch from the CP (close-phase) state to the OP (open-phase) state [121-123] . Furthermore, as an
individual guest molecule has its own gate opening pressure, this difference allows for high selectivity in gas
mixtures, i.e., the target molecule can open the gate while others cannot . Therefore, flexible MOFs with
[124]
S-shaped isotherms can be used as potential carbon capture adsorbents with good operability and high
selectivity for CO .
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ZnDatzBdc (Datz = 3,5-diamine-1,2,4-triazolate, Bdc = 1,4-benzenedicarboxylate) is a flexible MOF for
highly selective capture of CO [Figure 13]. X-ray diffraction studies confirmed a convertible structure
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conversion between its OP and CP states. Importantly, ZnDatzBdc exhibits an S-shaped CO isotherm,
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yielding appreciable CO workability of 94.9 cm cm under typical PVSA operations at 273 K, superior to
3
-3
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most reported flexible MOFs .
[125]
Mechanochemistry at the chemical reaction level mainly refers to the application of mechanical energy to
condensed substances, such as solids and liquids, by means of shear, abrasion, impact, and extrusion to
induce changes in their structure and physicochemical properties and to induce chemical reactions. Unlike
ordinary thermochemical reactions, mechanization, the driving force of the reaction, is mechanical energy
rather than thermal energy; thus, the reaction can be completed without high temperature, high pressure,
and other harsh conditions. It has been developing rapidly. This approach not only provides a green and
energy-efficient route for chemical transformations but also offers more possibilities for the expanded
preparation of materials . Ultramicroporous MOFs with negatively charged anionic columns, such as
[126]
2-
SiF and TiF , often exhibit promising applications in gas separation and CO capture. As shown in
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2-
Figure 14, a GeF pillared ultramicroporous MOF, ZU-36-Ni (also known as GeFSIX-3-Ni,
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