Degree

Doctor of Philosophy (PhD)

Department

Chemistry

Document Type

Dissertation

Abstract

Several metal complexes were investigated as potential hosts to execute controllable host- guest interactions using a redox stimulus. Previously, our group has synthesized new CuII m-xylylenebis(pyridyltriazole) (m-xpt) hosts and their redox properties were analyzed. In Chapter 2, we take advantage of the CuII host’s ability to perform redox to investigate its interaction with chloride guest ions. This study was executed with two main Cu-xpt hosts: [Cu2(m- xpt)2(NO3)2](PF6)2 and [Cu2(m-xpt)2Cl2]Cl2. The host-guest interaction was analyzed with additions of Cl− salt. Although there was evidence of redox-controlled binding of Cl–, the reactions could not be studied easily by electrochemistry.

In Chapter 3, we studied various ruthenium (III) β-diketonate complexes as potential hosts for alkali-metal ion guests. The cationic guests associate with the anionic RuII reduced host and are released upon oxidation to the neutral RuIII host. This was observed through a positive shift in host’s redox potential, [Ru(diket)3]0/−. In our work, we found that the Na+ association becomes stronger when the substituents on the diketone ligand increase in electron density. Three new ruthenium β-diketonate complexes are prepared as potential hosts with the intention of increasing Na+ affinity. Ru(dbm-2OMe)3 displayed greater sensitivity to the Na+ guest compared than any known ruthenium beta-diketonates. This host’s binding constant was determined to be two orders of magnitude higher than that of [Ru(dbm)3]−. These findings were also evidenced by UV-Vis, 1H NMR, spectroelectrochemistry, and crystallography analysis.

After the success of implementing host-guest interactions of anionic Ru hosts with guest cations, we decided to carry out analysis of several cationic Ru hosts with neutral and anionic guests in Chapters 4 and 5. These hosts will be oxidized in order to attract more anion guests. The guest interaction occurs through hydrogen bonding to the host’s ligands. The [Ru(bpy)(en)2](PF6)2, fac-[Ru(pypz)3](PF6)2, [Ru(bpy)(dpen)2](PF6)2, and [Ru(dmgH2)3](PF6)2 hosts display increased affinity for the anions when they are oxidized to ruthenium (III).

Date

11-1-2023

Committee Chair

Maverick, Andrew W.

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