ABSTRACT
Systems chemistry focuses on emergent properties in a complex matter. To design and demonstrate such emergent properties like autonomous motion in nanomotors as an output of an Operando Systems Chemistry Algorithm (OSCAL), we employ a 2-component system comprising porous organic frameworks (POFs) and soft-oxometalates (SOMs). The OSCAL governs the motion of the nanocarpets by the coding and reading of information in an assembly/disassembly cascade switched on by a chemical stimulus. Assembly algorithm docks SOMs into the pores of the POFs of the nanocarpet leading to the encoding of supramolecular structural information in the SOM-POF hybrid nanocarpet. Input of a chemical fuel to the system induces a catalytic reaction producing propellant gases and switches on the disassembly of SOMs that are concomitantly released from the pores of the SOM-POF nanocarpets producing a ballast in the system as a read-out of the coded information acquired in the supramolecular assembly. The OSCAL governs the motion of the nanocarpets in steps. The assembly/disassembly of SOM-POFs, releasing SOMs from the pores of SOM-POFs induced by a catalytic reaction triggered by a chemical stimulus coupled with the evolution of gas are the input. The output is the autonomous linear motion of the SOM-POF nanocarpets resulting from the read-out of the input information. This work thus manifests the operation of a designed Systems Chemistry algorithm which sets supramolecularly assembled SOM-POF nanocarpets into autonomous ballistic motion.
ABSTRACT
Visible light propelled nanomotors are a class of highly sought after active matter. Here we report a gold decorated semiconductor and a soft-oxometalate based TiO2-{Mo7}-Au nanomotor which can be propelled diffusiophoretically on exposure to visible light and show excellent photocatalytic activity. These systems exclude the use of any harsh toxic chemical as fuel and exhibit a speed of 10 µm s-1 in water. Their motion can also be controlled by rapid switching of light. We use these photocatalytic nanomotors for environmental cleansing as they can facilitate the removal of organic pollutants from water under visible light. In this work we have demonstrated the removal of two model organic pollutants methylene blue and benzyl bromide from water using these nanomotors.
ABSTRACT
The recent interest in self-propulsion raises an immediate challenge in facile and single-step synthesis of active particles. Here, we address this challenge and synthesize soft oxometalate nanomotors that translate ballistically in water using the energy released in a redox reaction of hydrazine fuel with the soft-oxometalates. Our motors reach a maximum speed of 370 body lengths per second and remain motile over a period of approximately 3 days. We report measurements of the speed of a single motor as a function of the concentration of hydrazine. It is also possible to induce a transition from single-particle translation to collective motility with biomimetic bands simply by tuning the loading of the fuel. We rationalize the results from a physicochemical hydrodynamic theory. Our nanomotors may also be used for transport of catalytic materials in harsh chemical environments that would otherwise passivate the active catalyst.
