Solid triphenylmethanol: A molecular material that undergoes multiple internal reorientational processes on different timescales

In solid triphenylmethanol, the molecules are arranged in hydrogen-bonded tetramers, and it is already well established that the hydrogen bonding in this material undergoes a dynamic switching process between different hydrogen bonding arrangements. In addition to this motion, we show here, from solid-state 2H NMR studies of the deuterated material (C6D5)3COH, that each phenyl ring in this material undergoes a 180°-jump reorientation about the C6D5–C(OH) bond, with an activation energy of ca. 50 kJ mol−1. The timescale for the phenyl ring dynamics is several orders of magnitude longer than the timescale for the hydrogen bond dynamics in this material, and is uncorrelated with the dynamics of the hydrogen bonding arrangement.