Zeolite NPO-Type Azolate Frameworks

Three-membered rings (3-rings) are an important structural motif in zeolite chemistry, but their formation remains serendipitous in reticular chemistry when designing zeolitic imidazolate frameworks (ZIFs). Herein, we report a design principle for constructing four new ZIFs, termed ZIF-1001 to -1004, from tetrahedral Zn-II centers (T), benzotriazolate (bTZ), and different functionalized benzimidazolates (RbIM) that adopt a new zeolite NPO-type topology built from 3-rings. Two factors were critical for this discovery: i) incorporating the bTZ linker within the structures formed 3-rings due to a angle(T-bTZ-T) angle of 120-130 degrees reminiscent of the angle(Ge-O-Ge) angle (130 degrees) observed in germanate zeolite-type structures having 3-rings; and ii) RbIM guided the coordination chemistry of bTZ to bind preferentially in an imidazolate-type mode. This series' ability to selectively capture CO2 from high-humidity flue gas and trap ethane from tail gas during shale gas extraction was demonstrated.

Automated summary

We report the design and synthesis of four new ZIFs with a novel zeolite topology built from 3-rings, using a new design principle. These materials demonstrate selective capture of CO2 and ethane under specific conditions.