Non-Equilibrium Transport Across Liquid Membranes Using Coordination Cages

Abstract

The host-guest chemistry of coordination cages underscores their utility in selectively extracting molecules, offering potential for chemical separation systems. However, the equilibrium constraint within bulk liquid membrane systems limits molecular transport efficiency to 50%, hindering widespread adoption. This thesis addresses this limitation by innovatively propelling compound transport away from equilibrium, utilizing light and chemical gradients. The first system investigates o-fluoroazobenzene (FAB) in bulk liquid membranes, analogous to the Maxwell’s Demon thought experiment. Light irradiation drives directional transport of FAB away from its initial equilibrium. Introducing a concentration gradient of naphthalene further drives the system out of equilibrium, elucidating competitive displacement mechanisms between guest compounds. Our second system employs the competitive displacement mechanism to construct an artificial antiport system, driving nonequilibrium distribution of guest compounds temporarily, using the gradient of another guest as a driving force. This thesis provides strategic insight into molecular transport through coordination cages, which will be useful for enhancing chemical separation efficiency.