HYPERVALENT IODINE BASED MACROCYCLES AND THEIR SUPRAMOLECULAR INTERACTIONS WITH GUESTS

Author

Krishna Pandey, Southern Illinois University CarbondaleFollow

Date of Award

12-1-2024

Degree Name

Doctor of Philosophy

Department

Chemistry

First Advisor

Plunkett, Kyle

Abstract

In this contribution, we successfully synthesize different variations of hypervalent iodine macrocycles (HIM) including novel phenylalanine base HIM. Next, this study explores the dynamic self-assembly and disassembly of hypervalent iodine-based macrocycles (HIMs) guided by secondary bonding interactions. The reversible disassembly and reassembly of HIMs are facilitated through anion binding via addition of tetrabutylammonium (TBA) salts or removal of the anion by addition of silver nitrate. The association constants for HIM monomers with TBA(Cl) and TBA(Br) are calculated and show a correlation with the strength of the iodine-anion bond. A unique tetracoordinate hypervalent iodine-based compound was identified as the disassembled monomer. In addition, this study also reveals the dynamic bonding nature of these macrocycles in solution, allowing for rearrangement and participation in dynamic bonding chemistry. In second research direction, A series of valine functionalized supramolecular hypervalent iodine macrocycles (HIMs) with enlarged aromatic cores, including naphthalene and anthraquinone, have been synthesized. Single crystal analysis shows the macrocycles consist of a slightly distorted cyclic planner interior with three carbonyl oxygens from the amino acid residues facing towards the center of the cage and all three alkyl groups above one plane. Owing to the enlarged aromatic core, the naphthalene-based HIMs were successfully co-crystallized with Buckminster Fullerene (C60) into a long-range columnar supramolecular structure. The assembled architecture displays a long-range pattern between HIM and C60 in a 2:3 ratio, respectively. Disassembly of the HIMs can be accomplished by adding anions of tetrabutylammonium (TBA) salts that selectively bind with the electron deficient iodine center in HIMs system. A comparative study of the associations constants and the binding energies for different aromatic-based HIMs with TBA(Cl) and TBA(Br) is presented. Lastly, this dissertation describes the solution- and solid-state assembly of phenylalanine based hypervalent iodine macrocycles (HIMs) with lithium and sodium cations. The metal cation binding of HIMs was evaluated by addition of lithium tetrakis(pentafluorophenyl)borate ethyl etherate (Li)BARF and sodium tetrakis[3,5-bis(trifluoromethyl)phenyl] borate (Na)BARF. The relatively electron rich, outwardly projected carbonyl oxygens of the HIM co-crystalize with the cations into bent supramolecular architectures. Both crystal structures show a pattern of assembly between HIM and metal cation in 2:1 ratio. While association with sodium leads to a polymer-like network, the lithium crystal structure was limited to dimeric assemblies of HIM. In the lithium coordinating complex, the oxygen-lithium-oxygen bond angle is approximately 98.83°, displaying a closer arrangement of two HIMs. In contrast, the sodium complex exhibits a more open orientation of two HIMs with an oxygen-sodium-oxygen bond angle close to 167.98°. Furthermore, a comparative study of association constants and binding energies for phenylalanine based HIM with (Li)BARF and (Na)BARF are presented.