A molecular information ratchet using a cone-shaped macrocycle

Abstract

•Ratcheting mechanisms are essential to devise molecular motors •A new information ratchet was developed relying on the shape of a cyclodextrin macrocycle •A cyclodextrin rotaxane with three stations ends up in the kinetically favored position •Information ratchet with dual input: position and orientation of a cone-shaped macrocycle Molecular information ratchets are key to the construction of autonomous, chemically fueled small-molecule motors. We have developed a novel type of information ratchet sensitive to two types of information: the position and the orientation of a moving macrocycle on an axle. The originality of this system comes from the use of a cone-shaped chiral macrocycle, a cyclodextrin, that presents two distinct faces toward the reactive site and is responsible for the kinetic biases observed. The reaction of functional groups on the axle next to the larger rim was found to be faster than that next to the smaller rim. An additional advantage of the conical shape of cyclodextrins is the possibility of selective face functionalization, allowing the addition of a component that will be active in the kinetic bias, which will improve the ratchet efficiency, thus offering new possibilities in the design of molecular motors. Molecular information ratchets are key to the construction of autonomous, chemically fueled small-molecule motors. We have developed a novel type of information ratchet sensitive to two types of information: the position and the orientation of a moving macrocycle on an axle. The originality of this system comes from the use of a cone-shaped chiral macrocycle, a cyclodextrin, that presents two distinct faces toward the reactive site and is responsible for the kinetic biases observed. The reaction of functional groups on the axle next to the larger rim was found to be faster than that next to the smaller rim. An additional advantage of the conical shape of cyclodextrins is the possibility of selective face functionalization, allowing the addition of a component that will be active in the kinetic bias, which will improve the ratchet efficiency, thus offering new possibilities in the design of molecular motors.