An Improved Model for One-Dimensional Polaronic Ferromagnetism: Poly-Meta-Phenylenefuchsone

Author: Anderson, Kraig Knute

Year: 1996

Degree: Dissertation (Ph.D.)

Advisor: Dougherty, Dennis A.

Committee Members: Grubbs, Robert H.; Dougherty, Dennis A.; Barton, Jacqueline K.; Okumura, Mitchio

Option: Chemistry

DOI: 10.7907/25a7-sf85

Abstract

The design, reductive doping, and magnetic characterization of poly-meta-phenylenefuchsone, an improved model for one-dimensional polaronic ferromagnetism, are described. Previous work demonstrated that delocalized radical cations, when linked through appropriate topologies, can exhibit ferromagnetic, or high spin interactions between unpaired electron spins. Consideration of these examples led to the choice of the radical anion of 2,6-di-tert-butylfuchsone as a spin containing unit, due to its relative stability, solubility, spin density, and ease of generation. Electrochemical doping of its polymers is more convenient and effective than chemical doping, resulting in a substantial increase in magnetic properties relative to previous models. The magnetic results are aided by dilution of the doped polymer in a diamagnetic solid, which is interpreted as reducing intermolecular antiferromagnetic interactions. The significant results of this model system provide clear directions for future designs, including improving solubility, spin density, doping efficiency, and defect suppression.

A tetraphenoxyl analog to existing quintet tetraradical A was envisioned. The synthesis and oxidation of its precursor tetraphenol I are described, as well as a number of simpler analogs. No evidence of high spin interactions was observed. Instead, the X-ray crystal structure of the product indicates that the oxidized tetraphenol undergoes ring closure of its central cyclobutane ring to form a bicyclobutane, which rapidly rearranges to a ring opened butadiene. The novel feature of this known rearrangement in the current system is that it occurs readily, even under very mild conditions.

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