Can one and two-dimensional solid-state NMR fingerprint zeolite framework topology?

Area of Science:

• Solid-state chemistry
• Materials science
• Spectroscopy

Background:

• Zeolites are crystalline aluminosilicates with diverse industrial applications.
• Accurate determination of zeolite framework structures is crucial for understanding their properties and optimizing their use.
• Traditional methods for zeolite structure resolution can be complex and time-consuming.

Purpose of the Study:

• To explore the utility of one-dimensional (1D) and two-dimensional (2D) silicon-29 (29Si) and silicon-29 (29Si)–oxygen-17 (17O) Nuclear Magnetic Resonance (NMR) as graph invariants for fingerprinting zeolite frameworks.
• To generate and compare hypothetical NMR signatures for known zeolite structures.
• To assess the discriminatory power of NMR data in identifying and distinguishing zeolite frameworks.

Main Methods:

• Utilized one-dimensional (1D) 29Si NMR and two-dimensional (2D) 29Si-29Si and 29Si-17O NMR techniques.
• Generated hypothetical 1D and 2D NMR signatures for 193 zeolite frameworks from the Atlas of Zeolite Structures.
• Analyzed and compared generated NMR signatures to determine their effectiveness in distinguishing zeolite structures.

Main Results:

• One-dimensional (1D) 29Si NMR data alone could distinguish nearly 20% of known zeolite frameworks.
• Incorporating 2D 29Si-29Si and 29Si-17O correlations significantly enhanced discrimination.
• The comprehensive NMR approach allowed for the unambiguous discrimination of up to 80% of the investigated zeolite frameworks.

Conclusions:

• Solid-state NMR data serve as robust graph invariants for characterizing zeolite frameworks.
• Despite challenges like isotopic labeling and long measurement times, 29Si and 17O NMR are valuable tools for zeolite structure resolution.
• The presented NMR-based fingerprinting approach is potentially applicable to other materials containing NMR-detectable nuclides.