1H relaxation and dynamics of triphenylbismuth in deuterated solvents

¹H spin-lattice relaxation experiments  have been performed for triphenylbismuth dissolved in fully deuterated glycerol and tetrahydrofuran. The experiments have been carried out in a broad frequency range, from 10kHz-40MHz, versus temperature. The data have been analyzed in terms of a relaxation model including two relaxation pathways: ¹H-¹H dipole-dipole interactions between intrinsic protons of  triphenylbismuth molecule and ¹H-²H dipole-dipole interactions between the solvent and solute molecules. As a result of the analysis, rotational correlation times of triphenylbismuth molecules in the solutions and relative translational diffusion coefficient between the solvent and solute molecules  have been determined.  Moreover, the role of the intramolecular ¹H-¹H relaxation contribution has been revealed, depending on the motional parameters, as a result of decomposing the overall relaxation  dispersion profile into contributions associated with the ¹H-¹H and ¹H-²H relaxation pathways. The possibility of accessing the contribution of the relaxation of the intrinsic protons is important from the perspective of exploiting Quadrupole Relaxation Enhancement effects  as a possible contrast mechanisms for Magnetic Resonance Imaging.