Control over Dethreading Kinetics Allows Evaluating the Entropy Stored in an Interlocked Molecular Machine Out-of-Equilibrium.

The operation of nanomachines is fundamentally different from that of their macroscopic counterparts. In particular, the role of solvent is critical yet rarely associated with machine functionality. Here we study a minimal model of one of the most advanced molecular machines to gain control of its operation by engineering components and the employed solvent. Operation kinetics were changed over more than four orders of magnitude and could be modulated by solvent. Leveraging solvent properties, it was possible to monitor the relaxation of the molecular machine towards equilibrium and measure the heat exchanged in the process. Our work expands the capabilities of acid-base powered molecular machines, confirming experimentally that such systems have a dominant entropy content.