Palladium(ii)-gated ion channels

Abstract

A simple ion channel has been developed that can be created or disassembled through the addition or removal of palladium(II).

Palladium(II)‐Mediated Assembly of Biotinylated Ion Channels

“…[9] We recently used the transverse (through-membrane) assembly of pyridyl-cholate 1 (Scheme 1) to develop Pd IIgated channels, where PdCl 2 assembled pyridyl cholate lipids into membrane-spanning [PdCl 2 (1) 2 ] complexes that acted as channels for the ingress of Na + and K + ions. [10] This supramolecular channel was inspired by covalent analogues, particularly the isocyanate-linked bischolates developed by Kobuke and co-workers. [11] They found that three to four membrane-spanning bischolates laterally assembled Abstract: Simple synthetic methodology has been used to create biotinylated pyridyl cholate lipids that can undergo multiple self-assembly events when inserted into phospholipid vesicles; Pd II links cholates into transmembrane lipids, while avidin laterally clusters these complexes together and concomitantly assembles the vesicles into aggregates.…”

Metal–Organic Scaffolds: Heavy‐Metal Approaches to Synthetic Ion Channels and Pores

“…[17] Facially amphiphilic cholates such as 11 have been reported previously to self-assemble into bundles that span one leaflet of a lipid bilayer membrane and have a hydrophilic interior to mediate ion transport.…”

“…On the other hand, increasing the size and complexity of the organic part, as in palladium-gated channel 10, promises access to metal-organic architectures of variable shape and increasing responsiveness to chemical and physical stimulation. [17] For example, expanded metal-organic frameworks already allow the nature of water within confined space to be studied on the molecular level. [25] Moreover, advanced metal-organic architectures with cylindrical shapes and the ability of molecular recognition have been developed.…”

“…The complementary single-channel currents have been recorded previously for bundles of monomeric, dimeric, and tetrameric cholate analogues. [1,17] The use of metal-organic scaffolds for reversible ligand gating is particularly important because the design of ligand-gated synthetic ion channels and pores is traditionally one of the most challenging topics in the field.…”

“…[1, 2,17] In channel 10, coordination chemistry is used to bring the cholate bundles in the two leaflets together. Namely, the pyridine ring attached to the cholate is thought to end up in the middle of the bilayer membrane.…”