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Longitudinal relaxation times T(sub 1) of laser-polarized xenon in water solutions containing alpha-cylodextrin and wheat nonspecific lipid transfer protein are measured. It reveals that even with an atom of high polarizability, such as xenon, the van der Waals energy is not sufficiently predominant to avoid large amplitude motions of an apolar guest around its average sites.

This article describes the study of a linear trimer and three polyarylamines PB1-3 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 J exchange coupling constant has been measured experimentally (J/k = 11.8 K) and compared quantitatively to DFT calculations. Most importantly, quartet and quintet spin states have been formed for PB3 and PB2, respectively. These last two doped polymers thus exhibit the highest spin states observed to date for linear polyarylamine compounds.

This report describes the study of a dimer d 2+ and a linear trimer t 3+ of amminium radical cations coupled by 3,4'-biphenyl spin coupling units. The synthesis of the parent diamine and triamine and their optical and electrochemical properties obtained by UV-visible and cyclic voltammetry are presented. The chemical doping of the parent diamine d and triamine t was performed quantitatively to obtain samples containing the corresponding dimer d 2+ and trimer t 3+ in almost pure high-spin states as evidenced by pulsed EPR nutation spectroscopy. The J coupling constants of the corresponding S = 1 and S = 3/2 spin states were measured (J/k = 135 K) and compared quantitatively to DFT calculations.

Polyarylamine containing meta-para-para-aniline units in the main chain and meta-para-aniline units in the pendant chains was synthesized. The polymer can be oxidized to radical cations in chemical or electrochemical ways. The presence of meta-phenylenes in the polymer chemical structure allows for the ferromagnetic coupling of electronic spins, which leads to the formation of high spin states. Detailed pulsed-EPR study indicates that the S = 2 spin state was reached for the best oxidation level. Quantitative magnetization measurements reveal that the doped polymer contains mainly S = 2 spin states and a fraction of S = 3/2 spin states. The efficiency of the oxidation was determined to be 74%. To the best of our knowledge, this polymer is the first example of a linear doped polyarylamine combining such high spin states with high doping efficiency.