Novel Resorcin[4]arenes as Potassium-Selective Ion-Channel and Transporter Mimics

Abstract

A series of novel resorcin-[4]arenes with extended pi systems have been synthesised and developed as potassium-selective transporters. Resorcin[4]arenes that feature crown ether moieties function as efficient carriers of K+ across bulk liquid membranes showing enhanced selectivity over the other alkali metal ions relative to a model system (benzo[15]crown-5). Incorporation of functionalities suitable for pore formation, in addition to an extra annulus of aromatic residues, gives molecules which have remarkable ion-channel-mimicking behaviour in a biological lipid bilayer with outstanding K+/Na+ selectivity.

A perspective to resorcinarene crowns

“…amphiphilicity and thus a capacity to form bilayers and a cyclic structure to allow the passage of ions, motivated Beer and co-workers 32 to choose resorcinarenes as platforms for their ion channel research. Unlike previous crown ether functionalized resorcinarenes, the crown ether moieties were attached as part of the lower rim (17a-b and 18a-b, Figure 6) in the original resorcinarene core synthesis 33 by using 4'-formylbenzo [15]crown-5 and 4'-formylbenzo [18]crown-6 as aldehydes in the condensation reaction with resorcinol.…”

<b>Potentiometric determination of K⁺ ions using a K⁺-selective electrode with macrocyclic liquid membrane</b>

“…Due to these properties, the crown ethers have been used in recent years to develop ion-selective electrodes for determination of alkali [3][4][5][6][7] and other transitional metals [8][9][10].…”

Synthetic multifunctional pores: deletion and inversion of anion/cation selectivity using pM and pH

“…1). Their rare characteristics compared to the other synthetic ion channels/pores, [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] i.e. the possibility to install functional groups along the ion-conducting pathway, encouraged the shift of our interest from biomimicry to practical applications.…”