Dynamic Studies of Guest Molecules in Metal-Organic Frameworks and Zeolites via Solid-State Nuclear Magnetic Resonance

Metal-organic frameworks (MOFs) are synthetic compounds with crystalline microporous structures, consisting of metal centres joined by organic linkers. Zeolites are a class of crystalline porous materials featuring negatively charged aluminosilicate frameworks and charge-balancing cations. In this work, solid-state nuclear magnetic resonance (SSNMR) is used to probe guest molecule locations and dynamics in MOFs and zeolites, yielding detailed informations of guest motion within these porous materials Chapter 2 describes SSNMR dynamic studies of 13CO2, 13CO and C2D4 adsorption behaviour in the α - zinc formate MOF, [Zn3(HCOO)6], which were performed at variable temperatures (VTs) using the 13C DEPTH-Echo, 2H quadrupolar echo, and 1H - 13C cross polarization pulse sequences. The simulated experimental spectra indicate these adsorbed guest molecules undergo the same type of specific, well-defined motions within the α - zinc formate MOF. Chapter 3 details studies on ion-exchanged FAU and LTA zeolites that were used as porous adsorbents to adsorb 13CO2 guests. The results suggest that the adsorption behaviour and dynamics of CO2 in zeolites are greatly influenced by (i) the specific charge balancing cations, (ii) the particular Si/Al ratios, and (iii) the type of zeolite framework. VT 13C DEPTH-echo and 1H-13C cross polarization SSNMR experiments have revealed that some CO2 guests are almost immobilized upon the extra-framework cations, while other CO2 guests form carbonate-like species while strongly interacting with cations