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Chemical Reviews Mar 2020Using anions to induce molecular structure is a rapidly growing area of dynamic and switchable supramolecular chemistry. The emphasis of this review is on helical anion... (Review)
Review
Using anions to induce molecular structure is a rapidly growing area of dynamic and switchable supramolecular chemistry. The emphasis of this review is on helical anion foldamers in solution, and many of the beautiful complexes described herein are accentuated by their crystal structures. Anion foldamers are defined as single- or multistrand complexes-often helical-that incorporate one or more anions. The review begins by discussing foldamer structure and nomenclature and follows with discourse on the anions which are employed. Recent advances in functional foldamers that bind a single anion are examined, including: induced chirality, stimuli-responsive dynamics, fluorescence changes, organocatalysis, anion transport, and halogen bonding. The review then inspects multianion foldamers, and this section is organized by the number of strands within the foldamer-from single- to triple-strand foldamers. Finally, the review is punctuated by recent hydrogen- and halogen-bonding triple-strand anion foldamers.
Topics: Anions; Molecular Conformation; Organic Chemicals; Polymers
PubMed: 32039583
DOI: 10.1021/acs.chemrev.9b00583 -
Chemical Reviews Jul 2023Anionic species are omnipresent and involved in many important biological processes. A large number of artificial anion receptors has therefore been developed. Some of... (Review)
Review
Anionic species are omnipresent and involved in many important biological processes. A large number of artificial anion receptors has therefore been developed. Some of these are capable of mediating transmembrane transport. However, where transport proteins can respond to stimuli in their surroundings, creation of synthetic receptors with stimuli-responsive functions poses a major challenge. Herein, we give a full overview of the stimulus-controlled anion receptors that have been developed thus far, including their application in membrane transport. In addition to their potential operation as membrane carriers, the use of anion recognition motifs in forming responsive membrane-spanning channels is discussed. With this review article, we intend to increase interest in transmembrane transport among scientists working on host-guest complexes and dynamic functional systems in order to stimulate further developments.
Topics: Receptors, Artificial; Biological Transport; Anions
PubMed: 37342028
DOI: 10.1021/acs.chemrev.3c00039 -
Nature Communications Aug 2022The quantification of anion binding by molecular receptors within lipid bilayers remains challenging. Here we measure anion binding in lipid bilayers by creating a...
The quantification of anion binding by molecular receptors within lipid bilayers remains challenging. Here we measure anion binding in lipid bilayers by creating a fluorescent macrocycle featuring a strong sulfate affinity. We find the determinants of anion binding in lipid bilayers to be different from those expected that govern anion binding in solution. Charge-dense anions HPO and Cl that prevail in dimethyl sulfoxide fail to bind to the macrocycle in lipids. In stark contrast, ClO and I that hardly bind in dimethyl sulfoxide show surprisingly significant affinities for the macrocycle in lipids. We reveal a lipid bilayer anion binding principle that depends on anion polarisability and bilayer penetration depth of complexes leading to unexpected advantages of charge-diffuse anions. These insights enhance our understanding of how biological systems select anions and guide the design of functional molecular systems operating at biomembrane interfaces.
Topics: Anions; Dimethyl Sulfoxide; Lipid Bilayers; Sulfates
PubMed: 35941124
DOI: 10.1038/s41467-022-32403-z -
Biochimica Et Biophysica Acta.... Feb 2022Phenylthiosemicarbazones (PTSCs) are proton-coupled anion transporters with pH-switchable behaviour known to be regulated by an imine protonation equilibrium....
Phenylthiosemicarbazones (PTSCs) are proton-coupled anion transporters with pH-switchable behaviour known to be regulated by an imine protonation equilibrium. Previously, chloride/nitrate exchange by PTSCs was found to be inactive at pH 7.2 due to locking of the thiourea anion binding site by an intramolecular hydrogen bond, and switched ON upon imine protonation at pH 4.5. The rate-determining process of the pH switch, however, was not examined. We here develop a new series of PTSCs and demonstrate their conformational behaviour by X-ray crystallographic analysis and pH-switchable anion transport properties by liposomal assays. We report the surprising finding that the protonated PTSCs are extremely selective for halides over oxyanions in membrane transport. Owing to the high chloride over nitrate selectivity, the pH-dependent chloride/nitrate exchange of PTSCs originates from the rate-limiting nitrate transport process being inhibited at neutral pH.
Topics: Anions; Chlorides; Crystallography, X-Ray; Hydrogen-Ion Concentration; Ion Transport; Kinetics; Nitrates; Protons; Thiosemicarbazones
PubMed: 34861222
DOI: 10.1016/j.bbamem.2021.183828 -
Chemistry (Weinheim An Der Bergstrasse,... Dec 2022The synthesis and characterisation of a library of acyclic antimony(III) and bismuth(III) triaryl pnictogen bonding (PnB) receptor systems are reported. In the...
The synthesis and characterisation of a library of acyclic antimony(III) and bismuth(III) triaryl pnictogen bonding (PnB) receptor systems are reported. In the first-generation receptor series, quantitative H NMR chloride titration experiments in THF solvent media reveal halide anion binding potency is intimately correlated with both the electronic-withdrawing nature of the aryl- substituent and the polarisability of the PnB donor. Further extensive anion binding investigations with the most potent Sb- and Bi-based PnB receptors: 1⋅Sb and 1⋅Bi , reveal novel selectivity profiles, both displaying Cl selectivity relative to the heavier halides and, impressively, to a range of highly basic oxoanions. The synthesis and preliminary chloride anion binding studies of a series of novel tripodal tris-proto-triazole triaryl Sb(III) and Bi(III) mixed PnB-HB receptor systems are also described. Whereas parent triphenyl Sb(III) and Bi(III) compounds are incapable of binding Cl in THF solvent media, the PnB-triazole HB host systems exhibit notable halide affinity.
Topics: Antimony; Bismuth; Chlorides; Anions; Halogens; Triazoles; Solvents
PubMed: 35968660
DOI: 10.1002/chem.202201838 -
International Journal of Molecular... Jan 2019Integral membrane proteins of the divalent anion/Na⁺ symporter (DASS) family are conserved from bacteria to humans. DASS proteins typically mediate the coupled uptake... (Review)
Review
Integral membrane proteins of the divalent anion/Na⁺ symporter (DASS) family are conserved from bacteria to humans. DASS proteins typically mediate the coupled uptake of Na⁺ ions and dicarboxylate, tricarboxylate, or sulfate. Since the substrates for DASS include key intermediates and regulators of energy metabolism, alterations of DASS function profoundly affect fat storage, energy expenditure and life span. Furthermore, loss-of-function mutations in a human DASS have been associated with neonatal epileptic encephalopathy. More recently, human DASS has also been implicated in the development of liver cancers. Therefore, human DASS proteins are potentially promising pharmacological targets for battling obesity, diabetes, kidney stone, fatty liver, as well as other metabolic and neurological disorders. Despite its clinical relevance, the mechanism by which DASS proteins recognize and transport anionic substrates remains unclear. Recently, the crystal structures of a bacterial DASS and its humanized variant have been published. This article reviews the mechanistic implications of these structures and suggests future work to better understand how the function of DASS can be modulated for potential therapeutic benefit.
Topics: Amino Acid Sequence; Animals; Anions; Binding Sites; Biological Transport; Humans; Protein Binding; Protein Conformation; Protein Multimerization; Sodium; Structure-Activity Relationship; Symporters
PubMed: 30669552
DOI: 10.3390/ijms20020440 -
Angewandte Chemie (International Ed. in... Dec 2022Despite the favorable properties that azetidine rings can engender on drug-compounds, methods for the diversity-oriented synthesis of azetidine-based structures are...
Despite the favorable properties that azetidine rings can engender on drug-compounds, methods for the diversity-oriented synthesis of azetidine-based structures are significantly underdeveloped. Herein, we report the successful realization of a multicomponent [1,2]-Brook rearrangement/strain-release-driven anion relay sequence and its application to the modular synthesis of substituted azetidines. The rapidity of the reaction, as confirmed by in situ infra-red spectroscopy, leverages the strain-release ring-opening of azabicyclo[1.1.0]butane to drive the equilibrium of the Brook rearrangement. The three electrophilic coupling partners, added sequentially to azabicyclo[1.1.0]butyl-lithium, could be individually varied to access a diverse compound library. The utility of this methodology was demonstrated in a 4-step synthesis of the EP2 receptor antagonist PF-04418948.
Topics: Azetidines; Cyclization; Anions
PubMed: 36300572
DOI: 10.1002/anie.202214049 -
International Journal of Molecular... Aug 2023In the last few decades, reticular chemistry has grown significantly as a field of porous crystalline molecular materials. Scientists have attempted to create the ideal... (Review)
Review
In the last few decades, reticular chemistry has grown significantly as a field of porous crystalline molecular materials. Scientists have attempted to create the ideal platform for analyzing distinct anions based on optical sensing techniques (chromogenic and fluorogenic) by assembling different metal-containing units with suitable organic linking molecules and different organic molecules to produce crystalline porous materials. This study presents novel platforms for anion recognition based on reticular chemistry with high selectivity, sensitivity, electronic tunability, structural recognition, strong emission, and thermal and chemical stability. The key materials for reticular chemistry, Metal-Organic Frameworks (MOFs), Zeolitic Imidazolate Frameworks (ZIFs), and Covalent-Organic Frameworks (COFs), and the pre- and post-synthetic modification of the linkers and the metal oxide clusters for the selective detection of the anions, have been discussed. The mechanisms involved in sensing are also discussed.
Topics: Anions; Oxides; Electronics; Metal-Organic Frameworks; Porosity
PubMed: 37685850
DOI: 10.3390/ijms241713045 -
Journal of the American Chemical Society May 2022Inspired by the success of its related sigma-hole congener halogen bonding (XB), chalcogen bonding (ChB) is emerging as a powerful noncovalent interaction with a...
Inspired by the success of its related sigma-hole congener halogen bonding (XB), chalcogen bonding (ChB) is emerging as a powerful noncovalent interaction with a plethora of applications in supramolecular chemistry and beyond. Despite its increasing importance, the judicious modulation of ChB donor strength remains a formidable challenge. Herein, we present, for the first time, the reversible and large-scale modulation of ChB potency by electrochemical redox control. This is exemplified by both the switching-ON of anion recognition via ChB oxidative activation of a novel bis(ferrocenyltellurotriazole) anion host and switching-OFF reductive ChB deactivation of anion binding potency with a telluroviologen receptor. The direct linking of the redox-active center and ChB receptor donor sites enables strong coupling, which is reflected by up to a remarkable 3 orders of magnitude modulation of anion binding strength. This is demonstrated through large voltammetric perturbations of the respective receptor ferrocene and viologen redox couples, enabling, for the first time, ChB-mediated electrochemical anion sensing. The sensors not only display significant anion-binding-induced electrochemical responses in competitive aqueous-organic solvent systems but can compete with, or even outperform similar, highly potent XB and HB sensors. These observations serve to highlight a unique (redox) tunability of ChB and pave the way for further exploration of the reversible (redox) modulation of ChB in a wide range of applications, including anion sensors as well as molecular switches and machines.
Topics: Anions; Chalcogens; Halogens; Oxidation-Reduction; Solvents
PubMed: 35522996
DOI: 10.1021/jacs.2c02924 -
Molecules (Basel, Switzerland) Jun 2022Cyclic pentaphenylalanine was studied as an efficient anion sensor for halides, thiocyanate and oxoanions in acetonitrile and methanol. Stability constants of the...
Cyclic pentaphenylalanine was studied as an efficient anion sensor for halides, thiocyanate and oxoanions in acetonitrile and methanol. Stability constants of the corresponding complexes were determined by means of fluorimetric, spectrophotometric, H NMR, and microcalorimetric titrations. A detailed structural overview of receptor-anion complexes was obtained by classical molecular dynamics (MD) simulations. The results of H NMR and MD studies indicated that the bound anions were coordinated by the amide groups of cyclopeptide, as expected. Circular dichroism (CD) titrations were also carried out in acetonitrile. To the best of our knowledge, this is the first example of the detection of anion binding by cyclopeptide using CD spectroscopy. The CD spectra were calculated from the structures obtained by MD simulations and were qualitatively in agreement with the experimental data. The stoichiometry of almost all complexes was 1:1 (receptor:anion), except for dihydrogen phosphate where the binding of dihydrogen phosphate dimer was observed in acetonitrile. The affinity of the cyclopeptide receptor was correlated with the structure of anion coordination sphere, as well as with the solvation properties of the examined solvents.
Topics: Acetonitriles; Anions; Molecular Dynamics Simulation; Peptides, Cyclic; Phosphates
PubMed: 35745042
DOI: 10.3390/molecules27123918