Ammonia capture within isoreticular metal-organic frameworks with rod secondary building units

Shinya Moribe, Zhijie Chen, Selim Alayoglu, Zoha H. Syed, Timur Islamoglu, Omar K. Farha*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The efficient removal, capture, and recycling of ammonia (NH3) constitutes a demanding process, thus the development of competent adsorbent materials is highly desirable. The implementation of metal-organic frameworks (MOFs), known for their tunability and high porosity, has attracted much attention for NH3 adsorption studies. Here, we report three isoreticular porphyrin-based MOFs containing aluminum (Al-PMOF), gallium (Ga-PMOF), and indium (In-PMOF) rod secondary building units with Brønsted acidic bridging hydroxyl groups. NH3 sorption isotherms in Al-PMOF demonstrated reversibility in isotherms. In contrast, the slopes of the adsorption isotherms in Ga-PMOF and In-PMOF were much steeper than Al-PMOF in lower pressure regions, with a decrease of NH3 adsorbed amounts observed between first cycle and second cycle measurements. Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) suggested that the strength of the Brønsted acidic -OH sites was controlled by the identity of the metal, which resulted in stronger interactions between ammonia and the framework in Ga-PMOF and In-PMOF compared to Al-PMOF.

Original languageEnglish (US)
JournalUnknown Journal
StatePublished - Aug 2 2019


  • Ammonia capture
  • Ammonia storage
  • Isoreticular synthesis
  • Metal-organic frameworks

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Science(all)

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