In modern organic chemistry, hypervalent (HV) iodine(III) compounds are frequently used as oxidizing agents but application of λ3-iodanes in polymer and material chemistry is still underexplored. This dissertation describes the preparation of dynamic and self-healing materials by employing ligand exchange reactions involving HV iodine(III) compounds of the type ArIL2 (Ar = Aryl, L = ligand, e.g., carboxylate or (pseudo)halide). These compounds can undergo ligand exchange reactions in presence of nucleophiles (Nu-) to form ArINu2. Diacetoxyiodo benzene was successfully employed as a crosslinker to prepare dynamic and self-healing gels derived from carboxylate-containing polymers. Furthermore, advantage was taken of the ability of diacetoxyiodo benzene to generate radicals upon UV light irradiation in order to convert the dynamic crosslinked structures to permanent (set) networks. Star polymers were prepared by mixing block copolymers Sty/MMA and AA with diacetoxyiodo benzene solution. The star polymers were characterized by dynamic light scattering and diffusion ordered NMR spectroscopy. Besides that, oligomeric and µ-oxo- HV iodine(III) compounds with two I-N bonds, containing 5-substituted tetrazoles as the ligands PhI(N4CR)2 (R = C6H5, and 4-CH3C6H4) were synthesized using PhIO. The crystal structure of one representative compound (an oligomer with three I atoms in the backbone and 5-phenyltetrazole end groups) was solved and refined from synchrotron powder X-ray diffraction. The novel compounds were characterized by cyclic voltammetry and were found to be strong oxidants. An attempt was made to prepare tetrazole based polymer networks. After synthesizing tetrazole containing oligomeric HV iodine(III) compounds, N-heterocycle-stabilized pseudocyclic λ3-iodane with tetrazole as the stabilizing group was synthesized and its thermal stability and redox activity were studied. The oxidative power of the polyvalent iodine compound with a tetrazole ligand was demonstrated by conducting oxidation of thioanisole to sulfoxide and dimerization of thiobenzamide to 3,5-diphenyl-1,2,4-thiadiazole.
Nicolay V. Tsarevsky
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Vaish, Avichal, "Hypervalent Iodine Compounds with Carboxylate and Tetrazolate Ligands" (2019). Chemistry Theses and Dissertations. 15.