[For the full NMR characterisation, please refer to the SI, Figure , Table , Figure , Figure ]. Specifically, we used NMR spectroscopy to determine the ensemble-averaged properties of AS4 in solvents having different polarity and hydrogen bonding properties. CDCl3 was chosen to examine the behaviour of the FerroTAC in an apolar environment. Its dielectric constant ε 8 closely approximates that of a lipid bilayer ε , making it an effective model for simulating the interior environment of a cell membrane. While water would have been the preferred solvent to simulate extracellular and intracellular environments, DMSO-d6 and methanol-d4 were used instead because of the poor compound solubility. Methanol-d4 has a relatively high dielectric constant ε 7 and offers the added advantage of acting as a hydrogen-bond donor, unlike the more commonly used DMSO-d6 ε = 46.7). Although DMSO-d6 has drawbacks such as higher viscosity and lack of hydrogenbond donor capability, it serves as a strong hydrogen-bond acceptor, effectively disrupting weak hydrogen bonds and is the most commonly used solvent in reference literature. We thus chose to use DMSO-d6 to benchmark the data from vt-NMR and ANMR experiments and methanol-d4 for NOESY analysis.