Ferromagnetic spin coupling through the 3,4′-biphenyl moiety in Arylamine Oligomers-experimental and computational study

This report describes the study of a dimer d2+ and a linear trimer t3+ 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 d2+ and trimer t3+ 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.