Themed collection The Supramolecular Chemistry of Anions

Guest editors Katrina Jolliffe and Philip Gale introduce the Organic & Biomolecular Chemistry themed collection on the supramolecular chemistry of anions.

Efforts to bind C-terminal D-Ala–D-Ala, mimicking the action of vancomycin, could lead to valuable new antibiotics with prolonged clinical effectiveness.

This review summarises recent developments in the use of macrocyclic and mechanically-interlocked host molecules as optical sensors for anions.

Supramolecular bis(cholyl) ion channels with oxalamide and hydrazide as selectivity filters are reported. The hydrazide system showed superior chloride transport activity to oxalamide due to better anion recognition.

An analogue of the tetracationic “Texas-sized” molecular box containing iodotriazole halogen bond-promoting subunits (“Ibox”) was prepared and found to recognize larger halides in organic media.

“Bare bones” pyridine dicarboxamide and pyrazine tetracarboxamide pincer frameworks were used to probe supramolecular anion binding. The influence of hydrophilic vs. hydrophobic environments and the potential for synergistic interactions in the ditopic hosts were explored.

Carboxylate-appended anion-responsive π-electronic molecules provided anion-binding self-assemblies, as anionic supramolecular polymers, resulting in ion-pairing assemblies.

In this manuscript we report a small molecule that can selectively bind to the bacterial lipid phosphatidylethanolamine and consequently functions as an antibacterial agent against certain Gram-positive bacteria.

A new family of squaramide-based anionophores (L1–L8) have been synthesised and fully characterised with the aim to investigate the effect of indolyl substituents on their anion binding and transmembrane transport properties.

Mechanistic studies on bicarbonate transport by simple di(thio)amidocarbazoles reveal two distinct transport mechanisms as well as potent antimicrobial properties.

We report a family of amidosquaramides with pKa values close to physiological pH. Intramolecular H-bonding affects anion binding leading to moderate Cl⁻ transmembrane transport at physiological pH, but under acidic conditions anion transport is effectively ‘switched on’.

Anion binding receptors based on bis-carbazolyl urea, with log binding constants up to above 5 towards acetate.

We present a new luminescent europium(III)-based anion receptor that binds to PAP (adenosine-3′,5′-diphosphate). The increased emission intensity and lifetime of the receptor-PAP complex was used to develop the first real-time assay of heparan sulfotransferase activity.

In this work we report the binding properties of rotaxane 1 towards a series of tetraalkylammonium salts of Cl⁻, OCN⁻ and NO₃⁻ anions in acetone and a CHCl₃/MeOH solvent mixture.

The acridinone 1,9-bis(thio)urea scaffold was repurposed for application in anion transport by appending a variety of electron-withdrawing groups to the peripheral phenyl moieties. High levels of activity were achieved which facilitated strictly electroneutral transport.

The synthesis and evaluation of a new anion receptor based on the 4-amido-1,8-naphthalimide scaffold is described.

Squaramide functionalised red-shifted azobenzenes for cooperative anion binding and enhanced photo-regulated transmembrane transport are reported.

Chloride transport across a membrane mediated by an ion pair receptor through K⁺/Cl⁻ or Na⁺/Cl⁻ cotransport with a selectivity towards the K⁺/Cl⁻ symport was realized.

The effect of hydrazones and related functional groups on the anion transport activity of thioureas is presented.

By using nanojars as anion binding agents, selectivity for either carbonate or sulfate can be achieved upon rigidification of the nanojar outer-shell with tethers of varying lengths between pairs of pyrazole ligands.

Mixed monolayer-protected gold nanoparticles with surface-bound zinc(II) dipicolylamine units allow the selective detection of adenosine monophosphate in an aqueous solution.

Simple cationic compounds containing O–H hydrogen bond donors bind anions very strongly in acetonitrile, and with moderate strength in 9 : 1 acetonitrile : water.