Formation of High-Spin States (<i>S</i> =
3/2 and 2) in Linear Oligo- and Polyarylamines
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Abstract
This article describes the study
of a linear trimer and three polyarylamines <b>PB1–3</b> containing a 3,4′-biphenyl ferromagnetic
coupler. The synthesis of the model compound (trimer) and the polymers
has been presented. The formation of radical cations was studied using
electrochemical and optical (UV–vis) methods. The chemical
oxidation of these compounds leads to the creation of high-spin states,
evidenced by pulsed EPR nutation spectroscopy. A quartet spin state
is observed for the trimer model compound, and its <i>J</i> exchange coupling constant has been measured experimentally (<i>J</i>/<i>k</i> = 11.8 K) and compared quantitatively
to DFT calculations. Most importantly, quartet and quintet spin states
have been formed for <b>PB3</b> and <b>PB2</b>, respectively.
These last two doped polymers thus exhibit the highest spin states
observed to date for linear polyarylamine compounds