Electronic Thesis and Dissertation Repository

Degree

Master of Science

Program

Chemistry

Supervisor

Yining Huang

Abstract

Metal-organic frameworks (MOFs) are a new class of porous materials that possess large three-dimensional voids in their structures. In this work, Solid-state NMR (SSNMR) is used to examine the dynamics of guest molecules at various temperatures in MOFs that possess different types of channels. Chapter 2 introduces the 13CO2 adsorption behavior in α-Mg formate studied by 13C SSNMR in conjunction with molecular dynamic simulation. 1H-13C cross polarization technique has successfully determined the adsorption sites of CO2 in this type of MOF to be hydrogen atoms. The dynamic analysis detects that at low temperature, all of the adsorbed CO2 undergo a combined motion consisting of a localized rotation upon a single hydrogen site and a non-localized two-sites hopping between two hydrogen sites, whereas at high temperature, a small portion of the adsorbed CO2 molecules obey only a localized rotation while the majority still follow the combined motion. Chapter 3 studies the ethylene adsorption behavior in α-Mg formate and CPO-27-M (M = Mg and Zn) by means of 2H SSNMR. Two types of ethylene are found in α-Mg formate following distinct motions. The majority of the adsorbed ethylene undergoes a combined motion of localized rotation and non-localized two-sites hopping, whereas the minority follows a localized rotation only. In CPO-27-M, all the adsorbed ethylene follows a combined motion of a localized rotation upon the unsaturated metal sites and a simultaneous non-localized hopping between six unsaturated metal sites. The affinity of ethylene towards CPO-27-Mg is found to be stronger than in CPO-27-Zn.

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