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Updated: Jan 20, 2026
Author Spotlight: Characterizing Porous Materials for Aiding the Development of Robust Metal-Organic Frameworks with Adsorption Behavior
Published on: March 8, 2024
Water-stable Adenine-based MOFs with Polar Pores for Selective CO2 Capture
Rahul Maity1, Himan Dev Singh1, Ankit Kumar Yadav1
1Department of Chemistry, Indian Institute of Science Education and Research, Pune, 411008, India.
Abstract:
Here, we report two novel water-stable amine-functionalized MOFs, namely IISERP-MOF26 ([NH2 (CH3 )2 ][Cu2 O(Ad)(BDC)]⋅(H2 O)2 (DMA), 1) and IISERP-MOF27 ([NH2 (CH3 )2 ]1/2 [Zn4 O(Ad)3 (BDC)2 ]⋅(H2 O)2 (DMF)1/2 , 2), which show selective CO2 capture capabilities. They are made by combining inexpensive and readily available terephthalic acid and N-rich adenine with Cu and Zn, respectively. They possess 1D channels decorated by the free amine group from the adenine and the polarizing oxygen atoms from the terephthalate units. Even more, there are dimethyl ammonium (DMA+ ) cations in the pore rendering an electrostatic environment within the channels. The activated Cu- and Zn-MOFs physisorb about 2.7 and 2.2 mmol g-1 of CO2 , respectively, with high CO2 /N2 and moderate CO2 /CH4 selectivity. The calculated heat of adsorption (HOA=21-23 kJ mol-1 ) for the CO2 in both MOFs suggest optimal physical interactions which corroborate well with their facile on-off cycling of CO2 . Notably, both MOFs retain their crystallinity and porosity even after soaking in water for 24 hours as well as upon exposure to steam over 24 hours. The exceptional thermal and chemical stability, favorable CO2 uptakes and selectivity and low HOA make these MOFs promising sorbents for selective CO2 capture applications. However, the MOF's low heat of adsorption despite having a highly CO2 -loving groups lined walls is quite intriguing.
Insights
Two new amine-functionalized metal-organic frameworks (MOFs) demonstrate selective carbon dioxide (CO2) capture. These water-stable MOFs show promising performance for CO2 separation applications.
Area of Science:
- Materials Science
- Chemistry
- Environmental Science
Background:
- Metal-organic frameworks (MOFs) are investigated for gas separation due to their tunable porosity and surface chemistry.
- Developing stable and selective MOFs for carbon dioxide (CO2) capture remains a significant challenge in environmental remediation and industrial processes.
Purpose of the Study:
- To synthesize and characterize novel amine-functionalized MOFs with enhanced water stability and selective CO2 capture capabilities.
- To evaluate the CO2 adsorption performance, selectivity, and stability of the synthesized MOFs under various conditions.
Main Methods:
- Synthesis of two novel amine-functionalized MOFs, IISERP-MOF26 and IISERP-MOF27, using inexpensive precursors like terephthalic acid and adenine with copper and zinc metals.
- Characterization of MOF structures, including 1D channels decorated with amine and polar groups, and assessment of their porosity.
- Evaluation of CO2 adsorption capacity and selectivity (CO2/N2, CO2/CH4) using gas physisorption measurements.
- Assessment of water stability through soaking in water and exposure to steam for 24 hours.
- Calculation of the heat of adsorption (HOA) to understand the interaction between CO2 and the MOF materials.
Main Results:
- Two water-stable amine-functionalized MOFs, IISERP-MOF26 and IISERP-MOF27, were successfully synthesized.
- The MOFs exhibit selective CO2 capture with uptakes of 2.7 and 2.2 mmol/g, respectively, and show high CO2/N2 and moderate CO2/CH4 selectivity.
- Both MOFs retained their crystallinity and porosity after 24 hours of soaking in water and exposure to steam, indicating exceptional stability.
- The calculated heat of adsorption (21-23 kJ/mol) suggests optimal physisorption interactions, facilitating facile CO2 on-off cycling.
Conclusions:
- The synthesized MOFs demonstrate significant potential as efficient and stable sorbents for selective CO2 capture.
- Their water stability, combined with favorable CO2 uptake and selectivity, makes them promising candidates for practical CO2 separation applications.
- The intriguing observation of low heat of adsorption despite CO2-philic groups warrants further investigation into the adsorption mechanisms.
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