Ultra-Microporous Zinc-Diaminotriazolate-Oxalate Metal Organic Framework with Nonlayered-Pillared Structure Showing High Carbon Dioxide Uptakes at Low Partial Pressures

Abstract

We report a zinc-diaminotriazolato-oxalate metal–organic framework (IISERP-MOF36, 1) inspired by the exceptional CO₂ selectivity demonstrated by its triazolate analogue, CALF-20. Unlike the CALF-20 family, 1 adopts a nonlayered, pillared structure, despite their similar composition. The 1D ultramicroporous channels in this MOF enhance strong interactions with the carbon dioxide CO₂. Additionally, the t-shaped orientation of CO₂ molecules within the pores promotes cooperative CO₂–CO₂ interactions, resulting in superior low-pressure CO₂ uptake compared to that of CALF-20. This suggests that 1 has potential as a sorbent in applications such as the natural gas combined cycle or direct air capture. However, despite its structural and compositional similarities to CALF-20, 1 exhibits reduced hydrophobicity due to subtle differences in the pore environment. These findings open possibilities for designing advanced sorbents combining the best characteristics of both of these MOFs.