Switching of Self-Assembly to Solvent-Assisted Assembly of Molecular Motor: Unveiling the Mechanisms of Dynamic Control on Solvent Exchange

Natural biological molecular motors are capable of performing several biological functions, such as fuel production, mobility, transport, and many other dynamic features. Inspired by these biological motors, scientists effectively synthesized artificial molecular motors to mimic several biological functionalities. Several molecular systems, from sensitive materials to molecular motors, are essential for controlling dynamic processes in larger assemblies. In this work, we discuss the self-assembly of molecular motors in water and how this self-assembly switches to the solvent-assisted assembly as solvent changes to a water-THF (tetrahydrofuran) mixture. We present an elaborate description of the morphological changes of molecular motor assemblies from pure water to a water-THF mixture to pure THF. Under the influence of THF solvent, molecular motors form an assembled structure by taking a sufficient number of THF molecules in between themselves, resulting in an assembled molecular motor with a softened core. So, molecular motor assembly swells in the water-THF mixture, and in pure water, it shrinks. This solvent-assisted assembled structure has a specific shape. We have confirmed this assembly as a solvent-assisted assembly with the help of molecular dynamics simulation and quantum chemical analysis. Molecular motor-THF and THF-THF interactions are the main responsible interactions for solvent-assisted assembly over self-assembly. This work is a perfect example of conversion between self-assembly (shrinking) and solvent-assisted assembly (swelling) of molecular motors by adding THF into water or vice versa. A spectacular check on the shrinking and swelling by merely altering solvents illustrates so many intriguing possibilities for an alteration of dynamic processes at the nanoscale.