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Singh A, Torres-Huerta A, Meyer F, Valkenier H. Anion transporters based on halogen, chalcogen, and pnictogen bonds: towards biological applications. Chem Sci 2024:d4sc04644g. [PMID: 39268212 PMCID: PMC11385378 DOI: 10.1039/d4sc04644g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2024] [Accepted: 09/01/2024] [Indexed: 09/15/2024] Open
Abstract
Motivated by their potential biological applications, anion receptors are increasingly explored as transmembrane transporters for anions. The vast majority of the reported anion transporters rely on hydrogen bonding to interact with the anions. However, in recent decades, halogen, chalcogen, and pnictogen bonding, collectively referred to as sigma-hole interactions, have received increasing attention. Most research efforts on these interactions have focused on crystal engineering, anion sensing, and organocatalysis. In recent years, however, these sigma-hole interactions have also been explored more widely in synthetic anion transporters. This perspective shows why synthetic transporters are promising candidates for biological applications. We provide a comprehensive review of the compounds used to transport anions across membranes, with a particular focus on how the binding atoms and molecular design affect the anion transport activity and selectivity. Few cell studies have been reported for these transporters based on sigma-hole interactions and we highlight the critical need for further biological studies on the toxicity, stability, and deliverability of these compounds to explore their full potential in biological applications, such as the treatment of cystic fibrosis.
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Affiliation(s)
- Anurag Singh
- Université libre de Bruxelles (ULB), Engineering of Molecular NanoSystems Avenue F. Roosevelt 50, CP165/64 1050 Brussels Belgium
| | - Aaron Torres-Huerta
- Université libre de Bruxelles (ULB), Engineering of Molecular NanoSystems Avenue F. Roosevelt 50, CP165/64 1050 Brussels Belgium
| | - Franck Meyer
- Université libre de Bruxelles (ULB), Microbiology, Bioorganic and Macromolecular Chemistry Unit, Faculty of Pharmacy Boulevard du Triomphe 1050 Brussels Belgium
| | - Hennie Valkenier
- Université libre de Bruxelles (ULB), Engineering of Molecular NanoSystems Avenue F. Roosevelt 50, CP165/64 1050 Brussels Belgium
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Johnson TG, Sadeghi-Kelishadi A, Langton MJ. Length dependent reversible off-on activation of photo-switchable relay anion transporters. Chem Commun (Camb) 2024; 60:7160-7163. [PMID: 38910566 DOI: 10.1039/d4cc02603a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/25/2024]
Abstract
A homologous series of azobenzene-derived photo-switchable ion relay transporters is reported. We reveal that both the length and geometry of the relay strongly affect transport rate, allowing the relative activity of the E and Z isomers to be reversed and hence the wavelengths of light used for on and off switching to be exchanged.
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Affiliation(s)
- Toby G Johnson
- Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA, UK.
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Docker A, Tse YC, Tay HM, Zhang Z, Beer PD. Ammonium halide selective ion pair recognition and extraction with a chalcogen bonding heteroditopic receptor. Dalton Trans 2024; 53:11141-11146. [PMID: 38888623 DOI: 10.1039/d4dt01376j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/20/2024]
Abstract
The first example of a heteroditopic receptor capable of cooperative recognition and extraction of ammonium salt (NH4X) ion-pairs is described. Consisting of a bidentate 3,5-bis-tellurotriazole chalcogen bond donor binding cleft, the appendage of benzo-15-crown-5 (B15C5) substituents to the tellurium centres facilitates binding of the ammonium cation via a co-facial bis-B15C5 sandwich complex, which serves to switch on chalcogen bonding-mediated anion binding potency. Extensive quantitative ion-pair recognition 1H NMR titration studies in CD3CN/CDCl3 (1 : 1, v/v) solvent media reveal impressive ion-pair binding affinities towards a variety of ammonium halide, nitrate and thiocyanate salts, with the heteroditopic receptor displaying notable ammonium halide salt selectivity. The prodigious solution phase NH4X recognition also translates to efficient solid-liquid and liquid-liquid extraction capabilities.
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Affiliation(s)
- Andrew Docker
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Yuen Cheong Tse
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Hui Min Tay
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, UK.
| | - Zongyao Zhang
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, UK.
| | - Paul D Beer
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, UK.
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McNaughton DA, York E, Rawling T, Gale PA. N, N'-Dimethylsquaramide as a central scaffold for anionophore design. Org Biomol Chem 2024; 22:4868-4876. [PMID: 38764358 DOI: 10.1039/d4ob00703d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2024]
Abstract
The N,N'-dimethylation of a diphenylsquaramide induces a conformational change in the orientation of the phenyl rings. This has been exploited to create a series of bis-urea, -thiourea and -squaramide anionophores. The compounds were shown to bind to Cl- using proton NMR titration techniques and to transport H+/Cl- through the lipid bilayers, whereas a non-methylated analogue displayed limited transport activity. Despite their potency in transport studies, the series had a negligible impact on cancer cell viability.
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Affiliation(s)
- Daniel A McNaughton
- School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney, Sydney, NSW 2007, Australia.
| | - Edward York
- School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney, Sydney, NSW 2007, Australia.
| | - Tristan Rawling
- School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney, Sydney, NSW 2007, Australia.
| | - Philip A Gale
- School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney, Sydney, NSW 2007, Australia.
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Bagha H, Hein R, Lim JYC, Durr CB, Sambrook MR, Beer PD. Halogen Bonding Tripodal Metallo-Receptors for Phosphate Recognition and Sensing in Aqueous-Containing Organic Media. Chemistry 2024; 30:e202302775. [PMID: 37792284 DOI: 10.1002/chem.202302775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 10/02/2023] [Accepted: 10/03/2023] [Indexed: 10/05/2023]
Abstract
The anion recognition and electrochemical anion-sensing properties of halogen-bonding (XB) tripodal zinc(II) receptors strategically designed and constructed for tetrahedral anion guest binding are described. The XB tris(iodotriazole)-containing hosts exhibit high affinities and selectivities for inorganic phosphate over other more basic, mono-charged oxoanions such as acetate and the halides in a competitive CD3 CN/D2 O (9 : 1 v/v) aqueous solvent mixture. 1 H NMR anion binding and electrochemical voltammetric anion sensing studies with redox-active ferrocene functionalised metallo-tripodal receptor analogues, reveal each of the XB tripods as superior anion complexants when compared to their tris(prototriazole)-containing, hydrogen bonding (HB) counterparts, not only exemplifying the halogen bond as a strong alternative interaction to the traditional hydrogen bond for molecular recognition but also providing rare evidence of the ability of XB receptors to preferentially bind the "harder" phosphate oxoanion over the "softer" and less hydrated halides in aqueous containing media.
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Affiliation(s)
- Hena Bagha
- Department of Chemistry, University of Oxford Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Robert Hein
- Department of Chemistry, University of Oxford Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Jason Y C Lim
- Department of Chemistry, University of Oxford Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Christopher B Durr
- Department of Chemistry, University of Oxford Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | | | - Paul D Beer
- Department of Chemistry, University of Oxford Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK
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6
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Johnson TG, Langton MJ. Molecular Machines For The Control Of Transmembrane Transport. J Am Chem Soc 2023; 145:27167-27184. [PMID: 38062763 PMCID: PMC10740008 DOI: 10.1021/jacs.3c08877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 11/21/2023] [Accepted: 11/22/2023] [Indexed: 12/21/2023]
Abstract
Nature embeds some of its molecular machinery, including ion pumps, within lipid bilayer membranes. This has inspired chemists to attempt to develop synthetic analogues to exploit membrane confinement and transmembrane potential gradients, much like their biological cousins. In this perspective, we outline the various strategies by which molecular machines─molecular systems in which a nanomechanical motion is exploited for function─have been designed to be incorporated within lipid membranes and utilized to mediate transmembrane ion transport. We survey molecular machines spanning both switches and motors, those that act as mobile carriers or that are anchored within the membrane, mechanically interlocked molecules, and examples that are activated in response to external stimuli.
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Affiliation(s)
- Toby G. Johnson
- Department of Chemistry, Chemistry
Research Laboratory, University of Oxford Mansfield Road, Oxford OX1 3TA United Kingdom
| | - Matthew J. Langton
- Department of Chemistry, Chemistry
Research Laboratory, University of Oxford Mansfield Road, Oxford OX1 3TA United Kingdom
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Min Tay H, Johnson TG, Docker A, Langton MJ, Beer PD. Exploiting the Catenane Mechanical Bond Effect for Selective Halide Anion Transmembrane Transport. Angew Chem Int Ed Engl 2023; 62:e202312745. [PMID: 37772928 DOI: 10.1002/anie.202312745] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 09/26/2023] [Accepted: 09/28/2023] [Indexed: 09/30/2023]
Abstract
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 additionally 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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Affiliation(s)
- Hui Min Tay
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA, United Kingdom
| | - Toby G Johnson
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA, United Kingdom
| | - Andrew Docker
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA, United Kingdom
| | - Matthew J Langton
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA, United Kingdom
| | - Paul D Beer
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA, United Kingdom
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