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Goodwin RJ, White NG. A Cationic Catechol Derivative Binds Anions in Competitive Aqueous Media. Chem Asian J 2024:e202301121. [PMID: 38269957 DOI: 10.1002/asia.202301121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Revised: 01/09/2024] [Indexed: 01/26/2024]
Abstract
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:D2 O and 7 : 3 d6 -acetone:D2 O (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:D2 O. 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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Affiliation(s)
- Rosemary J Goodwin
- Research School of Chemistry, Australian National University, Canberra, ACT, 2601, Australia
| | - Nicholas G White
- Research School of Chemistry, Australian National University, Canberra, ACT, 2601, Australia
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2
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Goodwin RJ, Docker A, MacDermott‐Opeskin HI, Aitken HM, O'Mara ML, Beer PD, White NG. Hydroxy Groups Enhance [2]Rotaxane Anion Binding Selectivity. Chemistry 2022; 28:e202200389. [PMID: 35293643 PMCID: PMC9321576 DOI: 10.1002/chem.202200389] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Indexed: 11/25/2022]
Abstract
We report the synthesis of two [2]rotaxanes containing an interlocked three dimensional binding cavity formed from a pyridinium bis(amide) axle component containing two phenol donors, and an isophthalamide based macrocycle. In the competitive solvent mixture 1 : 1 CDCl3 : CD3OD, one of the receptors exhibits a much higher selectivity preference for chloride than an analogous rotaxane without the hydroxy groups. X‐ray crystal structures reveal the chloride anion guest encapsulated within the interlocked binding cavity, though not all of the hydrogen bond donors are utilised. Computational semi‐empirical simulations indicate that secondary intermolecular interactions occur between the axle hydroxy hydrogen bond donors and the [2]rotaxane macrocycle components, contributing to a more preorganised binding pocket, which may be responsible for the observed enhanced selectivity.
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Affiliation(s)
- Rosemary J. Goodwin
- Research School of Chemistry Australian National University Canberra ACT Australia
| | - Andrew Docker
- Department of Chemistry University of Oxford Chemistry Research Laboratory Mansfield Road Oxford OX1 3TA UK
| | | | - Heather M. Aitken
- Research School of Chemistry Australian National University Canberra ACT Australia
| | - Megan L. O'Mara
- Research School of Chemistry Australian National University Canberra ACT Australia
| | - Paul D. Beer
- Department of Chemistry University of Oxford Chemistry Research Laboratory Mansfield Road Oxford OX1 3TA UK
| | - Nicholas G. White
- Research School of Chemistry Australian National University Canberra ACT Australia
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3
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Parks FC, Sheetz EG, Stutsman SR, Lutolli A, Debnath S, Raghavachari K, Flood AH. Revealing the Hidden Costs of Organization in Host-Guest Chemistry Using Chloride-Binding Foldamers and Their Solvent Dependence. J Am Chem Soc 2022; 144:1274-1287. [PMID: 35015538 DOI: 10.1021/jacs.1c10758] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Preorganization is a key concept in supramolecular chemistry. Preorganized receptors enhance binding by minimizing the organization costs associated with adopting the conformation needed to orient the binding sites toward the guest. Conversely, poorly organized receptors show affinities below what is possible based on the potential of their specific binding interactions. Despite the fact that the organization energy is paid each time like a tax, its value has never been measured directly, though many compounds have been developed to measure its effects. We present a method to quantify the hidden costs of receptor organization by independently measuring the contribution it makes to chloride complexation by a flexible foldameric receptor. This method uses folding energy to approximate organization energy and relies on measurement of the coil-helix equilibrium as a function of solvent. We also rely on the finding, established with rigid receptors, that affinity is inversely related to the solvent dielectric and expect the same for the foldamer's helically organized state. Increasing solvent polarity across nine dichloromethane-acetonitrile mixtures we see an unusual V-shape in affinity (decrease then increase). Quantitatively, this shape arises from weakened hydrogen-bonding interactions with solvent polarity followed by solvent-driven folding into an organized helix. We confirm that dielectric screening impacts the stability of host-guest complexes of flexible foldamers just like rigid receptors. These results experimentally verify the canonical model of binding (affinity depends on the sum of organization and noncovalent interactions). The picture of how solvent impacts complex stability and conformational organization thereby helps lay the groundwork for de novo receptor design.
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Affiliation(s)
- Fred C Parks
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Edward G Sheetz
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Sydney R Stutsman
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Alketa Lutolli
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Sibali Debnath
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Krishnan Raghavachari
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Amar H Flood
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
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4
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Kondo SI, Okada N, Abe S, Tanaka R, Yamamura M, Unno M. Anion recognition by silanetriol in acetonitrile. Org Biomol Chem 2022; 20:8925-8931. [DOI: 10.1039/d2ob01596j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Anion recognition ability and organocatalytic activity of a silanetriol are firstly presented by comparing with those of a series of silanol derivatives.
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Affiliation(s)
- Shin-ichi Kondo
- Department of Chemistry, Faculty of Science, Yamagata University, Yamagata 990-8560, Japan
| | - Natsumi Okada
- Department of Chemistry and Chemical Biology, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma 376-8515, Japan
| | - Shiori Abe
- Department of Chemistry, Faculty of Science, Yamagata University, Yamagata 990-8560, Japan
| | - Ryoji Tanaka
- Department of Chemistry and Chemical Biology, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma 376-8515, Japan
- Sagami Chemical Research Institute, Hayakawa 2743-1, Ayase, Kanagawa 252-1193, Japan
| | - Masaki Yamamura
- Department of Chemistry and Chemical Biology, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma 376-8515, Japan
- Faculty of Engineering, Toyama Prefectural University, 5180 Kurokawa, Imizu, Toyama 939-0398, Japan
| | - Masafumi Unno
- Department of Chemistry and Chemical Biology, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma 376-8515, Japan
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5
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Goodwin RJ, Blyth MT, Fung AKK, Smith LM, Norcott PL, Tanovic S, Coote ML, White NG. Simple acyclic molecules containing a single charge-assisted O-H group can recognize anions in acetonitrile : water mixtures. Org Biomol Chem 2021; 19:2794-2803. [PMID: 33720236 DOI: 10.1039/d1ob00282a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Hydroxypyridinium and hydroxyquinolinium compounds containing acidic O-H groups attached to a cationic aromatic scaffold were synthesized, i.e. N-methyl-3-hydroxypyridinium (1+) and N-methyl-8-hydroxyquinolinium (2+). These very simple compounds are capable of binding to chloride very strongly in CD3CN and with moderate strength in 9 : 1 CD3CN : D2O. Comparison with known association constants reveals that 1+ and 2+ bind chloride in CD3CN or CD3CN : D2O with comparable affinities to receptors containing significantly more hydrogen bond donors and/or higher positive charges. Crystal structures of both compounds with coordinating anions were obtained, and feature short O-Hanion hydrogen bonds. A receptor containing two hydroxyquinolinium groups was also prepared. While the low solubility of this compound caused difficulties, we were able to demonstrate chloride binding in a competitive 1 : 1 CD3CN : CD3OD solvent mixture. Addition of sulfate to this compound results in the formation of a crystallographically-characterised solid state anion coordination polymer.
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Affiliation(s)
- Rosemary J Goodwin
- Research School of Chemistry, Australian National University, Canberra, ACT, Australia.
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Fadler RE, Al Ouahabi A, Qiao B, Carta V, König NF, Gao X, Zhao W, Zhang Y, Lutz JF, Flood AH. Chain Entropy Beats Hydrogen Bonds to Unfold and Thread Dialcohol Phosphates inside Cyanostar Macrocycles To Form [3]Pseudorotaxanes. J Org Chem 2021; 86:4532-4546. [PMID: 33636075 PMCID: PMC8063573 DOI: 10.1021/acs.joc.0c02887] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The recognition of substituted phosphates underpins many processes including DNA binding, enantioselective catalysis, and recently template-directed rotaxane synthesis. Beyond ATP and a few commercial substrates, however, little is known about how substituents effect organophosphate recognition. Here, we examined alcohol substituents and their impact on recognition by cyanostar macrocycles. The organophosphates were disubstituted by alcohols of various chain lengths, dipropanol, dihexanol, and didecanol phosphate, each accessed using modular solid-phases syntheses. Based on the known size-selective binding of phosphates by π-stacked dimers of cyanostars, threaded [3]pseudorotaxanes were anticipated. While seen with butyl substituents, pseudorotaxane formation was disrupted by competitive OH···O- hydrogen bonding between both terminal hydroxyls and the anionic phosphate unit. Crystallography also showed formation of a backfolded propanol conformation resulting in an 8-membered ring and a perched cyanostar assembly. Motivated by established entropic penalties accompanying ring formation, we reinstated [3]pseudorotaxanes by extending the size of the substituent to hexanol and decanol. Chain entropy overcomes the enthalpically favored OH···O- contacts to favor random-coil conformations required for seamless, high-fidelity threading of dihexanol and didecanol phosphates inside cyanostars. These studies highlight how chain length and functional groups on phosphate's substituents can be powerful design tools to regulate binding and control assembly formation during phosphate recognition.
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Affiliation(s)
- Rachel E Fadler
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Abdelaziz Al Ouahabi
- Université de Strasbourg, CNRS, Institut Charles Sadron UPR22, Strasbourg, 67034, France
| | - Bo Qiao
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Veronica Carta
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Niklas F König
- Université de Strasbourg, CNRS, Institut Charles Sadron UPR22, Strasbourg, 67034, France
| | - Xinfeng Gao
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Wei Zhao
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Yankai Zhang
- Université de Strasbourg, CNRS, Institut Charles Sadron UPR22, Strasbourg, 67034, France
| | - Jean-François Lutz
- Université de Strasbourg, CNRS, Institut Charles Sadron UPR22, Strasbourg, 67034, France
| | - Amar H Flood
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
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