Abstract: Molecules represent the smallest arbitrarily-designable quantum entities and they show promise for several applications in quantum science. Some difficulties arise from their large number of degrees of freedom which lead to unfavourable spin-phonon coupling pathways, but at the same time they offer significant opportunities, for example tuning the spin-electric coupling that can arise in the presence of significant spin-orbit coupling. I will discuss our recent work in which we have developed methods to accurately and efficiently calculate both these effects ab initio, allowing us to probe the origins of these effects and how they may either be suppressed or enhanced through chemical design.