Design, synthesis, and gas adsorption properties of porous cuboctahedral coordination cages
Date
2021
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Delaware
Abstract
This dissertation discusses the synthesis and gas adsorption properties of high surface area, ligand terminated, porous coordination cages. Chapter 1 discusses the motivation of this work towards applications in small molecule separations and high pressure methane storage along with the relevant background leading to the field of porous coordination cages. Chapter 2 details the synthesis of two novel chromium based coordination cages. One variant of the cage demonstrated remarkably high surface area and thermal stability. Due to redox active metal in the structure, the cage was evaluated for O2/N2 separation potential. By spectroscopy measurements, O2 was determined to bind in a superoxide fashion and by isotherms at 195 K, 85 % of the metal sites were to bind O2. Chapter 3 details the synthesis of M24(bdc)24(dabco)24 which feature M24(bdc)24 as the featured pore in the structure. Through the use of neutron powder diffraction experiments, the binding locations and ethane and ethylene were able to be determined. Chapter 4 evaluates a series of high porosity, M24(tBu-bdc)24 cuboctahedral cages for high pressure methane storage. Modeling of powder neutron data in M24(Me-bdc)24(dabco)6 compounds and calculations were used to understand how methane interacts within the pores of the cuboctahedral cages. Chapter 5 evaluates two ruthenium based porous materials for C2H4/C2H6 separation potential. XPS, XAS, PGAA, and INS along with neutron powder diffraction experiments were performed to determine the anion at the RuII,III metal node. Hydrocarbon isotherms on both materials revealed the materials show a 10 kJ/mol heat of adsorption difference between C2H4 and C2H6.
Description
Keywords
Gas adsorption, Cuboctahedral coordination cages, Spectroscopy