Ion transport across
lipid membranes in biology is controlled by
stimuli-responsive membrane channels and molecular machine ion pumps
such as ATPases. Here, we report a synthetic molecular machine-like
ion transport relay, in which transporters on opposite sides of a
lipid bilayer membrane facilitate transport by passing ions between
them. By incorporating a photo-responsive telescopic arm into the
relay design, this process is reversibly controlled in response to
irradiation with blue and green light. Transport occurs only in the
extended state when the length of the arm is sufficient to pass the
anion between transporters located on opposite sides of the membrane.
In contrast, the contracted state of the telescopic arm is too short
to mediate effective transport. The system acts as a stimuli-responsive
ensemble of machine-like components, reminiscent of robotic arms in
a factory assembly line, working cooperatively to mediate ion transport.
This work points to new prospects for using lipid bilayer membranes
as scaffolds for confining, orientating, and controlling the relative
positions of molecular machines, thus enabling multiple components
to work in concert and opening up new applications in biological contexts.
Lipid bilayer membranes form compartments requisite for life. Interfacing supramolecular systems, including receptors, catalysts, signal transducers and ion transporters, enables the function of the membrane to be controlled in artificial...
Synthetic supramolecular transmembrane anionophores have
emerged
as promising anticancer chemotherapeutics. However, key to their targeted
application is achieving spatiotemporally controlled activity. Herein,
we report a series of chalcogen-bonding diaryl tellurium-based transporters
in which their anion binding potency and anionophoric activity are
controlled through reversible redox cycling between Te oxidation states.
This unprecedented in situ reversible multistate
switching allows for switching between ON and OFF anion transport
and is crucially achieved with biomimetic chemical redox couples.
Selective transmembrane transport of chloride over competing proton or hydroxide transport is key for the therapeutic applications of anionophores, but remains a significant challenge. Current approaches rely on enhancing chloride...
Stereogenic sp3-hybridized carbon centres are fundamental building blocks of chiral molecules. Unlike dynamic stereogenic motifs, such as sp3-nitrogen centres or atropisomeric biaryls, sp3-carbon centres are usually fixed, requiring intermolecular reactions to undergo configurational changes. Here we report the internal enantiomerization of fluxional carbon cages and the consequences of their adaptive configurations for the transmission of stereochemical information. The sp3-carbon stereochemistry of the rigid tricyclic cages is inverted through strain-assisted Cope rearrangements, emulating the low-barrier configurational dynamics typical for sp3-nitrogen inversion or conformational isomerism. This dynamic enantiomerization can be stopped, restarted or slowed by external reagents, while the configuration of the cage is controlled by neighbouring, fixed stereogenic centres. As part of a phosphoramidite–olefin ligand, the fluxional cage acts as a conduit to transmit stereochemical information from the ligand while also transferring its dynamic properties to chiral-at-metal coordination environments, influencing catalysis, ion pairing and ligand exchange energetics.
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