Coordination polymers of the alkaline earth metals for applications in synthesis and gas storage

<p>The work presented in this thesis outlines our efforts to synthesize alkaline earth metal</p> <p>coordination complexes that could potentially serve as gas storage and synthetic precursor</p> <p>materials. The properties of these complexes are heavily influenced by factors such as the</p> <p>propensity to aggregate and the absence of energetically available d-orbitals which provide</p> <p>directionality. These often pose a challenge in obtaining suitable, stable compounds.</p> <p>Some challenges in the crystallization of alkaline earth coordination complexes involve</p> <p>the precipitation of insoluble aggregates. Thus, a great part of the work focused on studying</p> <p>suitable reaction conditions towards the formation of X-ray quality crystals for structural</p> <p>elucidation. Slow concentration and hydro/solvothermal techniques, among others, were prime</p> <p>crystallization methods in this work.</p> <p>The bulk of this thesis is divided in two parts. The first part details our attempts to</p> <p>synthesize metal organic frameworks (MOFs) of Mg, Ca, Sr and Ba. Our ligands of choice were</p> <p>the p, m, o-pyridinecarboxylic acids which provide two different binding sites. These consist of</p> <p>an N-donor and an anionic carboxylic acid, the N-donor located at different positions in the</p> <p>pyridyl ring depending on the isomer. These are also of low cost and soluble in different organic</p> <p>solvents.</p> <p>The use of pyridinecarboxylic acids resulted in the systematic isolation of five</p> <p>magnesium coordination complexes, three of which exhibit open-framework character and</p> <p>remain stable after removal of guests, and two of which are hydrogen bonded networks. Further,</p> <p>systematic work with the heavier metals resulted in three fully 3-dimensional complexes based</p> <p>on Ca, Sr and Ba and one hydrogen-bonded Ca complex. A pattern is observed when using the</p> <p>linear p or angular m-pyridinecarboxylic acid in the presence of MeOH/DMF mixtures, in which</p> <p>3-dimensional motifs with open-framework (p) and dense (m) character (Mg, Ca and Sr) are</p> <p>displayed. The dimensionality decreases in the presence of water or strongly coordinating</p> <p>donors, leading to the formation of hydrogen bound or 2-dimensional complexes.</p> <p>The second part of this thesis involves the isolation of crown stabilized alkaline earth</p> <p>tosylates. The work resulted in the isolation of four new crown stabilized alkaline earth tosylates.</p> <p>Trends observed include an increase in coordination number as the size of the metal increases.</p> <p>Variation of crown:metal stoichiometry was also studied and resulted in two different calcium</p> <p>species displaying fully separated (1:1) and contact separated (1:2) ion association modes. For Sr</p> <p>and Ba, (1:1) stoichiometries resulted in hydrogen bound contact species.</p> <p>This thesis provides a selection of alkaline earth metal coordination complexes. The</p> <p>preparation of these complexes has led to the elucidation of their synthetic routes. Full</p> <p>characterization of the complexes is also provided.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Year

2014

Author dc:creator

• Rosado Flores, Peter Josue

Contributors dc:contributor

• Karin Ruhlandt-Senge

• Physical Sciences and Mathematics

Repository record dc:identifier

https://surface.syr.edu/etd/200

OAI identifier oai:identifier

oai:surface.syr.edu:etd-1200