As described in the Results, we used the Umbrella Sampling technique to reconstruct the free energy landscape of the Zr 4+ -DFO and Zr 4+ -4HMS complex in solvent as a function of the CN . These constrained simulations were obtained using the Amber suite combined with tools from PLUMED open source library. The free energy landscapes are then reconstructed using the WHAM method (code from Ref. 29.)