The emerging field of organic spintronics is especially promising for new technologies, owing to the long spin coherence times, large flexibility and low production costs of the materials. However, a greater understanding of the fundamental mechanisms behind coherent transport in organic molecules is required to fully utilise their potential. We have recently performed high field ALC measurements on two series of molecules, polycrystalline metal-tris(hydroxyquinolate) and a triethylsylil series based on changing the backbone. For both series of molecules, we see a clear linear increase of electron spin relaxation rate, suggesting hyperfine interactions are not responsible. We wish to study the anthradithiophene series substituted with C, Si and Ge in the periphery. This will help us understand the role of backbone and ligands in the electron spin relaxation.