writer：Liangjun Li,? Haitao Xue,? Ying Wang,? Pinhui Zhao,? Dandan Zhu,? Min Jiang,? and Xuebo Zhao*,?
keywords：Metal Metathesis
source：期刊
specific source：ACS Appl. Mater. Interfaces 2015, 7, 25402?25412
Issue time：2015年

Metal?organic frameworks (MOFs) with constricted pores can

increase the adsorbate density of gas and facilitate effective CO2 separation from

flue gas or natural gas due to their enhanced overlapping of potential fields of the

pores. Herein, an MOF with constricted pores, which was formed by narrow

channels and blocks of functional groups, was fabricated from the assembly of a

methyl-functionalized ligand and Zn(II) centers (termed NPC-7-Zn). Structural

analysis of the as-synthesized NPC-7-Zn reveals a series of zigzag pores with pore

diameters of ～0.7 nm, which could be favorable for CO2 traps. For reinforcing the

framework stability, a solvothermal metal metathesis on the pristine MOF NPC-

7-Zn was performed, and a new Cu(II) MOF (termed NPC-7-Cu) with an

identical framework was produced. The influence of the reaction temperatures on

the metal metathesis process was investigated. The results show that the

constricted pores in NPC-7-Zn can induce kinetic issues that largely slow the

metal metathesis process at room temperature. However, this kinetic issue can be

solved by applying higher reaction temperatures. The modified MOF NPC-7-Cu exhibits significant improvements in framework

stability and thus leads to a permanent porosity for this framework. The constricted pore structure enables enhanced potential

fields for these pores, rendering this MOF with high adsorbate densities for CO2 and high adsorption selectivity for a CO2/N2

gas mixture. The adsorption kinetic studies reveal that CH4 has a faster diffusion rate constant than CO2, showing a surface

diffusion controlled mechanism for CO2 and CH4 adsorption.