Transport of Molecular Cargoes By Coordination Cages Between Immiscible Liquid Phases
Directed transport of materials against chemical potential gradients is a fundamental feature of living systems, underpinning processes that range from transport through cell membranes to neurotransmission. The development of artificial active cargo transport could enable new modes of chemical purification and pumping. Coordination cages with inner cavities are able to encapsulate and release guest molecules based on their size and shape complementarity, providing a new technological basis to transport molecular cargoes. This thesis presents systems using coordination cages to transport materials, targeting chemical separation and material shifted away from equilibrium. In these systems, coordination cages cross liquid phase boundaries upon exposing to heat stimuli or diffuse within aqueous membrane layers to promote the passage of materials. The first system employs a thermoresponsive cage, FeII4L4, to transport encapsulated cargo across multiple phase boundaries, allowing for longer-distance transport than would be possible using a single pair of phases. The system constitutes a novel class of heat engine when thermal energy drives the material transport over a distance. The second system introduces aqueous membranes consist of coordination cages, FeII4L6 or CoII4L4, to separate chemical compounds from organic phases. The coordination cages diffuse within the membrane and selectively encapsulate the target compounds from stock mixtures at room temperature. The studies demonstrate the potential applications of cages for chemical purification without heating requires. Finally, the aqueous cage membranes are further developed to drive flows of materials away from the initial equilibrium when irradiated to light, making the system analogous to Maxwell’s demon. The thesis demonstrates that coordination cages will be useful means for chemical separation and material transport independently to chemical gradients.
Supramolecular chemistry, Coordination cages, Phase transfer, Bulk liquid membranes, Thermoresponsive cages, Selective molecular transport
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