Hydroxy Groups Enhance [2]Rotaxane Anion Binding Selectivity

Goodwin, Rosemary; Docker, Andrew; MacDermott-Opeskin, Hugo; Aitken, Heather M.; O’Mara, Megan L.; Beer, Paul D.; White, Nicholas G.

doi:10.1002/chem.202200389

Cited by 18 publications

(10 citation statements)

References 49 publications

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“…[ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ] Inspired by nature's oxoanion‐selective protein designs, during the past two decades we have strategically constructed mechanically interlocked host structures (MIMs) for anion recognition. [ 35 , 36 , 37 , 38 , 39 , 40 ] Recently the integration of halogen bonding (XB) donors to decorate acyclic, macrocyclic and MIM receptor binding sites has proven to be a promising alternative to traditionally employed hydrogen bonding (HB) interactions by virtue of the former's often superior anion binding strength, more stringent linear interaction geometries and contrasting selectivity profiles. [ 41 , 42 , 43 , 44 , 45 , 46 ] Surprisingly, the use of interlocked structures for ion‐pair recognition remains remarkably rare, with the handful of reported receptors largely limited to [2]rotaxane topologies,[ 47 , 48 , 49 , 50 , 51 , 52 ] and one example of a [2]catenane topology being used to this end.…”

Section: Introductionmentioning

confidence: 99%

Halogen‐Bonding Heteroditopic [2]Catenanes for Recognition of Alkali Metal/Halide Ion Pairs

et al. 2022

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The first examples of halogen bonding (XB) heteroditopic homo [2]catenanes were prepared by discrete Na + template-directed assembly of oligo(ethylene glycol) units derived from XB donor-containing macrocycles and acyclic bis-azide precursors, followed by a Cu I -mediated azide-alkyne cycloaddition macrocyclisation reaction. Extensive 1 H NMR spectroscopic studies show the [2]catenane hosts exhibit positive cooperative ion-pair recognition behaviour, wherein XB-mediated halide recognition is enhanced by alkali metal cation pre-complexation. Notably, subtle changes in the catenanes' oligo(ethylene glycol) chain length dramatically alters their ion-binding affinity, stoichiometry, complexation mode, and conformational dynamics. Solutionphase and single-crystal X-ray diffraction studies provide evidence for competing host-separated and directcontact ion-pair binding modes. We further demonstrate the [2]catenanes are capable of extracting solid alkalimetal halide salts into organic media.

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Section: Introductionmentioning

confidence: 99%

Halogen‐Bonding Heteroditopic [2]Catenanes for Recognition of Alkali Metal/Halide Ion Pairs

et al. 2022

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“…While relatively few cationic OÀ H receptors have been reported, [42][43][44][45][46][47][48][49] those that have been prepared have shown relatively high anion affinities in competitive solvents. For example, Yu [44] and Alfonso [45] separately investigated anion recognition using chiral hosts containing cationic imidazolium groups and hydroxy motifs, in both cases demonstrating binding of several anions in very polar organic solvents.…”

Section: Introductionmentioning

confidence: 99%

“…For example, Yu [44] and Alfonso [45] separately investigated anion recognition using chiral hosts containing cationic imidazolium groups and hydroxy motifs, in both cases demonstrating binding of several anions in very polar organic solvents. More recently, we have investigated acyclic [46] and interlocked [48] anion hosts containing amide and hydroxy donors and a pyridinium group and were able to demonstrate selective anion recognition in polar organic solvents containing a small amount of water. We have also demonstrated that the very simple cationic compounds 1 + and 2 + (Figure 1) containing a single charge‐assisted O−H group can bind anions weakly in 9 : 1 CD 3 CN:D 2 O [47] .…”

Section: Introductionmentioning

confidence: 99%

A Cationic Catechol Derivative Binds Anions in Competitive Aqueous Media

Goodwin,

White

2024

Chemistry An Asian Journal

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A simple dihydroxy isoquinolinium molecule (3+) was prepared by a modification of a literature procedure. Interestingly, during optimisation of the synthesis a small amount of the natural product pseudopalmatine was isolated, and characterised for the first time by X‐ray crystallography. Compound 3+ contains a catechol motif and positive charge on the same scaffold and was found to be a potent anion receptor, binding sulfate strongly in 8 : 2 d6‐acetone:D2O and 7 : 3 d6‐acetone:D2O (Ka>104 and 2,100 M−1, respectively). Unsurprisingly, chloride binding was much weaker, even in the less polar solvent mixture 9 : 1 d6‐acetone:D2O. The sulfate binding is remarkably strong for such a simple molecule, however anion binding studies were complicated by the tendency of the molecule to react with BPh4− or BF4− species during anion metathesis reactions. This gave two unusual zwitterions containing tetrahedral boronate centres, which were both characterised by X‐ray crystallography.

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“…[5] Indeed, we and others have demonstrated that MIMs not only raise the bar in terms of anion affinity, but crucially provide a strategy to augment selectivity profiles through a 'mechanical bond effect'. [6][7][8][9][10][11][12][13][14][15] Surprisingly, however, the use of interlocked structures to mediate ion transport remains rare and have thus far been restricted to [2]rotaxane architectures [16][17][18][19] and a molecular knot based ion channel system. [20] Lewis acidic sigma-hole interactions such as halogen bonding (XB) and chalcogen bonding (ChB) are remarkably potent non-covalent means by which anion recognition can be achieved, exhibiting dramatically enhanced affinities relative to traditional strategies including hydrogen bonding (HB), even in highly competitive aqueous media.…”

Section: Introductionmentioning

confidence: 99%

Exploiting the Catenane Mechanical Bond Effect for Selective Halide Anion Transmembrane Transport

Min Tay,

Johnson,

Docker

et al. 2023

Angew Chem Int Ed

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The first examples of [2]catenanes capable of selective anion transport across a lipid bilayer are reported. The neutral halogen bonding (XB) [2]catenanes were prepared via a chloride template‐directed strategy in an unprecedented demonstration of using XB∙∙∙anion interactions to direct catenane assembly from all‐neutral components. Anion binding experiments in aqueous‐organic solvent media revealed strong halide over oxoanion selectivity, and a marked enhancement in the chloride and bromide affinities of the catenanes relative to their constituent macrocycles. The catenanes displayed an anti‐Hofmeister binding preference for bromide over the larger iodide anion, illustrating the efficacy of employing sigma‐hole interactions in conjunction with the mechanical bond effect to tune receptor selectivity. Transmembrane anion transport studies conducted in POPC LUVs revealed that the catenanes were more effective anion transporters than the constituent macrocycles, with high chloride over hydroxide selectivity, which is critical to potential therapeutic applications of anionophores. Remarkably these outperform existing acyclic halogen bonding anionophores with regards to this selectivity. Record chloride over nitrate anion transport selectivity was also observed. This represents a rare example of the direct translation of intrinsic anion binding affinities to anion transport behaviour, and demonstrates the key role of the catenane mechanical bond effect for enhanced anion transport selectivity.

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Hydroxy Groups Enhance [2]Rotaxane Anion Binding Selectivity

Cited by 18 publications

References 49 publications

Halogen‐Bonding Heteroditopic [2]Catenanes for Recognition of Alkali Metal/Halide Ion Pairs

Halogen‐Bonding Heteroditopic [2]Catenanes for Recognition of Alkali Metal/Halide Ion Pairs

A Cationic Catechol Derivative Binds Anions in Competitive Aqueous Media

Exploiting the Catenane Mechanical Bond Effect for Selective Halide Anion Transmembrane Transport

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