1
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Stauber JM. Tailoring Metallosupramolecular Glycoassemblies for Enhancing Lectin Recognition. Angew Chem Int Ed Engl 2024; 63:e202408751. [PMID: 38829965 DOI: 10.1002/anie.202408751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Revised: 06/01/2024] [Accepted: 06/03/2024] [Indexed: 06/05/2024]
Abstract
Multivalency is a fundamental principle in nature that leads to high-affinity intermolecular recognition through multiple cooperative interactions that overcome the weak binding of individual constituents. For example, multivalency plays a critical role in lectin-carbohydrate interactions that participate in many essential biological processes. Designing high-affinity multivalent glycoconjugates that engage lectins results in systems with the potential to disrupt these biological processes, offering promising applications in therapeutic design and bioengineering. Here, a versatile and tunable synthetic platform for the synthesis of metallosupramolecular glycoassemblies is presented that leverages subcomponent self-assembly, which employs metal ion templates to generate complex supramolecular architectures from simple precursors in one pot. Through ligand design, this approach provides precise control over molecular parameters such as size, shape, flexibility, valency, and charge, which afforded a diverse family of well-defined hybrid glyconanoassemblies. Evaluation of these complexes as multivalent binders to Concanavalin A (Con A) by isothermal titration calorimetry (ITC) demonstrates the optimal saccharide tether length and the effect of electrostatics on protein affinity, revealing insights into the impact of synthetic design on molecular recognition. The presented studies offer an enhanced understanding of structure-function relationships governing lectin-saccharide interactions at the molecular level and guide a systematic approach towards optimizing glyconanoassembly binding parameters.
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Affiliation(s)
- Julia M Stauber
- Department of Chemistry and Biochemistry, University of California, La Jolla, 92092, San Diego, California, United States
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2
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Ward MD. New insights into coordination-cage based catalysis. Chem Commun (Camb) 2024; 60:10464-10475. [PMID: 39224947 DOI: 10.1039/d4cc03678f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
This review article summarises work from the author's group on catalysis using coordination cages over the (approximate) period 2018-2024. Recent insights discussed include (i) the general mechanism of catalysis, which involves co-location of reaction partners using orthogonal interactions involving the cage cavity (neutral hydrophobic substrates) and the surface anion-based reaction partners; (ii) the role of the cage exterior surface in facilitating catalysis in some cases; (iii) quantitative analysis of anion-binding to the cage surface, as a complement to measurement of binding constants of neutral guests inside the cavity; (iv) a new type of redox-based catalysis using reactive oxygen species, which are generated by reaction of oxidants such as H2O2 and HSO5- with Co(II)/Co(III) redox couples in the cage superstructure. Collectively the results discussed provide signficant new possibilities for further exploration of catalysis using supramolecular assemblies.
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Affiliation(s)
- Michael D Ward
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
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3
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Sudittapong B, Taylor CGP, Williams J, Griffiths RJ, Hiscock JR, Ward MD. Coordination-cage binding and catalysed hydrolysis of organophosphorus chemical warfare agent simulants. RSC Adv 2024; 14:26032-26042. [PMID: 39161455 PMCID: PMC11331485 DOI: 10.1039/d4ra04705b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Accepted: 08/13/2024] [Indexed: 08/21/2024] Open
Abstract
The use of organophosphorus chemical warfare agents still remains an ongoing global threat. Here we investigate the binding of small-molecule organic guests including phosphate esters, sulfonate esters, carbonate esters and a sulfite ester - some of which act as simulants for organophosphorus chemical warfare agents - in the cavity of a water-soluble coordination cage. For several of these guest species, binding constants in the range 102 to 103 M-1 were determined in water/DMSO (98 : 2 v/v) solution, through a combination of fluorescence and 1H NMR spectroscopy, and subsequent fitting of titration data to a 1 : 1 binding isotherm model. For three cage/guest complexes crystallographic structure determinations were possible: in two cases (with guests phenyl methanesulfonate and phenyl propyl carbonate) the guest lies inside the cavity, forming a range of CH⋯O hydrogen-bonding interactions with the cage interior surface involving CH groups on the cationic cage surface that act as H-bond donors and O atoms on the guests that act as H-bond acceptors. In a third case, with the guest 4-nitrophenyl-methanesulfonate, the guest lies in the spaces outside a cage cavity between cages and forms weak CH⋯O interactions with the cage exterior surface: the cavity is occupied by a network of H-bonded water molecules, though this guest does show cavity binding in solution. For the isomeric guests 4-nitrophenyl-methanesulfonate and 4-nitrophenyl methyl sulfite, hydrolysis in water/DMSO (98 : 2 v/v) could be monitored colorimetrically via appearance of the 4-nitrophenolate anion; both showed accelerated hydrolysis rates in the presence of the host cage with second-order rate constants for the catalysed reactions in the range 10-3 to 10-2 M-1 s-1 at pH 9. The typical rate dependence on external pH and the increased reaction rates when chloride ions are present (which can bind inside the cavity and displace other cavity-bound guests) imply that the catalysed reaction actually occurs at the external surface of the cage rather than inside the cavity.
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Affiliation(s)
| | | | - James Williams
- Department of Chemistry, University of Warwick Coventry CV4 7AL UK
| | - Rebecca J Griffiths
- School of Chemistry and Forensic Science, University of Kent Canterbury CT2 7NH UK
| | - Jennifer R Hiscock
- School of Chemistry and Forensic Science, University of Kent Canterbury CT2 7NH UK
| | - Michael D Ward
- Department of Chemistry, University of Warwick Coventry CV4 7AL UK
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4
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Martí-Centelles V, Piskorz TK, Duarte F. CageCavityCalc ( C3): A Computational Tool for Calculating and Visualizing Cavities in Molecular Cages. J Chem Inf Model 2024; 64:5604-5616. [PMID: 38980812 PMCID: PMC11267575 DOI: 10.1021/acs.jcim.4c00355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 06/05/2024] [Accepted: 06/26/2024] [Indexed: 07/11/2024]
Abstract
Organic(porous) and metal-organic cages are promising biomimetic platforms with diverse applications spanning recognition, sensing, and catalysis. The key to the emergence of these functions is the presence of well-defined inner cavities capable of binding a wide range of guest molecules and modulating their properties. However, despite the myriad cage architectures currently available, the rational design of structurally diverse and functional cages with specific host-guest properties remains challenging. Efficiently predicting such properties is critical for accelerating the discovery of novel functional cages. Herein, we introduce CageCavityCalc (C3), a Python-based tool for calculating the cavity size of molecular cages. The code is available on GitHub at https://github.com/VicenteMartiCentelles/CageCavityCalc. C3 utilizes a novel algorithm that enables the rapid calculation of cavity sizes for a wide range of molecular structures and porous systems. Moreover, C3 facilitates easy visualization of the computed cavity size alongside hydrophobic and electrostatic potentials, providing insights into host-guest interactions within the cage. Furthermore, the calculated cavity can be visualized using widely available visualization software, such as PyMol, VMD, or ChimeraX. To enhance user accessibility, a PyMol plugin has been created, allowing nonspecialists to use this tool without requiring computer programming expertise. We anticipate that the deployment of this computational tool will significantly streamline cage cavity calculations, thereby accelerating the discovery of functional cages.
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Affiliation(s)
- Vicente Martí-Centelles
- Instituto
Interuniversitario de Investigación de Reconocimiento Molecular
y Desarrollo Tecnológico (IDM), Universitat
Politècnica de València, Universitat de València, Camino de Vera s/n, Valencia 46022, Spain
- CIBER
de Bioingeniería Biomateriales y Nanomedicina, Instituto de Salud Carlos III, Madrid 28029, Spain
- Departamento
de Química, Universitat Politècnica
de València, Camino de Vera
s/n, Valencia 46022, Spain
| | - Tomasz K. Piskorz
- Chemistry
Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K.
| | - Fernanda Duarte
- Chemistry
Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K.
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5
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Lee B, Go B, Jung B, Park J. Unlocking High Porosity: Post-Synthetic Solvothermal Treatment of Cu-Paddlewheel Based Metal-Organic Cages. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2308393. [PMID: 38150648 DOI: 10.1002/smll.202308393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Indexed: 12/29/2023]
Abstract
Metal-organic cages (MOCs) have garnered significant attention due to their unique discrete structures, intrinsic porosity, designability, and tailorability. However, weak inter-cage interactions, such as van der Waals forces and hydrogen bonding can cause solid-state MOCs to lose structural integrity during desolvation, leading to the loss of porosity. In this work, a novel strategy to retain the permanent porosity of Cu-paddlewheel-based MOCs, enabling their use as heterogeneous catalysts is presented. Post-synthetic solvothermal treatments in non-coordinating solvents, mesitylene, and p-xylene, effectively preserve the packing structures of solvent-evacuated MOCs while preventing cage agglomeration. The resulting MOCs exhibit an exceptional N2 sorption capacity, with a high surface area (SBET = 1934 m2 g-1 for MOP-23), which is among the highest reported for porous MOCs. Intriguingly, while the solvothermal treatment reduced Cu(II) to Cu(I) in the Cu-paddlewheel clusters, the MOCs with mixed-valenced Cu(I)/Cu(II) maintained their crystallinity and permanent porosity. The catalytic activities of these MOCs are successfully examined in copper(I)-catalyzed hydrative amide synthesis, highlighting the prospect of MOCs as versatile reaction platforms.
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Affiliation(s)
- Byeongchan Lee
- Department of Physics and Chemistry, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungang-daero, Dalseong-gun, Daegu, 42988, Republic of Korea
| | - Bogyeong Go
- Department of Physics and Chemistry, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungang-daero, Dalseong-gun, Daegu, 42988, Republic of Korea
| | - Byunghyuck Jung
- Department of Physics and Chemistry, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungang-daero, Dalseong-gun, Daegu, 42988, Republic of Korea
| | - Jinhee Park
- Department of Physics and Chemistry, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungang-daero, Dalseong-gun, Daegu, 42988, Republic of Korea
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6
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Dorrat JC, Taylor CGP, Young RJ, Solea AB, Turner DR, Dennison GH, Ward MD, Tuck KL. A Study on Auto-Catalysis and Product Inhibition: A Nucleophilic Aromatic Substitution Reaction Catalysed within the Cavity of an Octanuclear Coordination Cage. Chemistry 2024; 30:e202400501. [PMID: 38433109 DOI: 10.1002/chem.202400501] [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: 02/03/2024] [Revised: 02/29/2024] [Accepted: 03/01/2024] [Indexed: 03/05/2024]
Abstract
The ability of an octanuclear cubic coordination cage to catalyse a nucleophilic aromatic substitution reaction on a cavity-bound guest was studied with 2,4-dinitrofluorobenzene (DNFB) as the guest/substrate. It was found that DNFB undergoes a catalysed reaction with hydroxide ions within the cavity of the cubic cage (in aqueous buffer solution, pH 8.6). The rate enhancement of kcat/kuncat was determined to be 22, with cavity binding of the guest being required for catalysis to occur. The product, 2,4-dinitrophenolate (DNP), remained bound within the cavity due to electrostatic stabilisation and exerts two apparently contradictory effects: it initially auto-catalyses the reaction when present at low concentrations, but at higher concentrations inhibits catalysis when a pair of DNP guests block the cavity. When encapsulated, the UV/Vis absorption spectrum of DNP is red-shifted when compared to the spectrum of free DNP in aqueous solution. Further investigations using other aromatic guests determined that a similar red-shift on cavity binding also occurred for 4-nitrophenolate (4NP) at pH 8.6. The red-shift was used to determine the stoichiometry of guest binding of DNP and 4NP within the cage cavity, which was confirmed by structural analysis with X-ray crystallography; and was also used to perform catalytic kinetic studies in the solution-state.
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Affiliation(s)
- Jack C Dorrat
- School of Chemistry, Monash University, Melbourne, VIC, 3800, Australia
| | | | - Rosemary J Young
- School of Chemistry, Monash University, Melbourne, VIC, 3800, Australia
| | - Atena B Solea
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
| | - David R Turner
- School of Chemistry, Monash University, Melbourne, VIC, 3800, Australia
| | - Genevieve H Dennison
- CBRN Defence, Sensors and Effectors Division, Defence Science and Technology Group, Fishermans Bend, VIC, 3207, Australia
- Electro Optics Sensing and Electromagnetic Warfare, Sensors and Effectors Division, Defence Science and Technology Group, Edinburgh, SA, 5111, Australia
| | - Michael D Ward
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
| | - Kellie L Tuck
- School of Chemistry, Monash University, Melbourne, VIC, 3800, Australia
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7
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Montà-González G, Ortiz-Gómez E, López-Lima R, Fiorini G, Martínez-Máñez R, Martí-Centelles V. Water-Soluble Molecular Cages for Biological Applications. Molecules 2024; 29:1621. [PMID: 38611902 PMCID: PMC11013847 DOI: 10.3390/molecules29071621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 04/01/2024] [Accepted: 04/02/2024] [Indexed: 04/14/2024] Open
Abstract
The field of molecular cages has attracted increasing interest in relation to the development of biological applications, as evidenced by the remarkable examples published in recent years. Two key factors have contributed to this achievement: First, the remarkable and adjustable host-guest chemical properties of molecular cages make them highly suitable for biological applications. This allows encapsulating therapeutic molecules to improve their properties. Second, significant advances have been made in synthetic methods to create water-soluble molecular cages. Achieving the necessary water solubility is a significant challenge, which in most cases requires specific chemical groups to overcome the inherent hydrophobic nature of the molecular cages which feature the organic components of the cage. This can be achieved by either incorporating water-solubilizing groups with negative/positive charges, polyethylene glycol chains, etc.; or by introducing charges directly into the cage structure itself. These synthetic strategies allow preparing water-soluble molecular cages for diverse biological applications, including cages' anticancer activity, anticancer drug delivery, photodynamic therapy, and molecular recognition of biological molecules. In the review we describe selected examples that show the main concepts to achieve water solubility in molecular cages and some selected recent biological applications.
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Affiliation(s)
- Giovanni Montà-González
- Instituto Interuniversitario de Investigación de Reconocimiento Molecular y Desarrollo Tecnológico (IDM), Universitat Politècnica de València, Universitat de València, Camino de Vera s/n, 46022 Valencia, Spain; (G.M.-G.); (E.O.-G.); (G.F.)
- Departamento de Química, Universitat Politècnica de València, Camí de Vera s/n, 46022 Valencia, Spain
| | - Eduardo Ortiz-Gómez
- Instituto Interuniversitario de Investigación de Reconocimiento Molecular y Desarrollo Tecnológico (IDM), Universitat Politècnica de València, Universitat de València, Camino de Vera s/n, 46022 Valencia, Spain; (G.M.-G.); (E.O.-G.); (G.F.)
- Departamento de Química, Universitat Politècnica de València, Camí de Vera s/n, 46022 Valencia, Spain
| | - Rocío López-Lima
- Instituto Interuniversitario de Investigación de Reconocimiento Molecular y Desarrollo Tecnológico (IDM), Universitat Politècnica de València, Universitat de València, Camino de Vera s/n, 46022 Valencia, Spain; (G.M.-G.); (E.O.-G.); (G.F.)
| | - Guillermo Fiorini
- Instituto Interuniversitario de Investigación de Reconocimiento Molecular y Desarrollo Tecnológico (IDM), Universitat Politècnica de València, Universitat de València, Camino de Vera s/n, 46022 Valencia, Spain; (G.M.-G.); (E.O.-G.); (G.F.)
| | - Ramón Martínez-Máñez
- Instituto Interuniversitario de Investigación de Reconocimiento Molecular y Desarrollo Tecnológico (IDM), Universitat Politècnica de València, Universitat de València, Camino de Vera s/n, 46022 Valencia, Spain; (G.M.-G.); (E.O.-G.); (G.F.)
- Departamento de Química, Universitat Politècnica de València, Camí de Vera s/n, 46022 Valencia, Spain
- CIBER de Bioingeniería Biomateriales y Nanomedicina, Instituto de Salud Carlos III, 46022 Valencia, Spain
- Unidad Mixta de Investigación en Nanomedicina y Sensores, Instituto de Investigación Sanitaria La Fe (IISLAFE), Universitat Politècnica de València, Avenida Fernando Abril Martorell, 106, 46026 Valencia, Spain
- Unidad Mixta UPV-CIPF de Investigación en Mecanismos de Enfermedades y Nanomedicina, Centro de Investigación Príncipe Felipe, Universitat Politècnica de València, Avenida Eduardo Primo Yúfera, 3, 46012 Valencia, Spain
| | - Vicente Martí-Centelles
- Instituto Interuniversitario de Investigación de Reconocimiento Molecular y Desarrollo Tecnológico (IDM), Universitat Politècnica de València, Universitat de València, Camino de Vera s/n, 46022 Valencia, Spain; (G.M.-G.); (E.O.-G.); (G.F.)
- Departamento de Química, Universitat Politècnica de València, Camí de Vera s/n, 46022 Valencia, Spain
- CIBER de Bioingeniería Biomateriales y Nanomedicina, Instituto de Salud Carlos III, 46022 Valencia, Spain
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8
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Ghosh A, Pruchyathamkorn J, Fuertes Espinosa C, Nitschke JR. Light-Driven Purification of Progesterone from Steroid Mixtures Using a Photoresponsive Metal-Organic Capsule. J Am Chem Soc 2024; 146:2568-2573. [PMID: 38230667 PMCID: PMC10835723 DOI: 10.1021/jacs.3c11005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 12/28/2023] [Accepted: 12/28/2023] [Indexed: 01/18/2024]
Abstract
Chemical separations are expensive, consuming 10-15% of humanity's global energy budget. Many current separation methods employ thermal energy for distillation, often through the combustion of carbon-containing fuels, or extractions and crystallizations from organic solvents, which must then be discarded or redistilled, with a substantial energetic cost. The direct use of renewable energy sources, such as light, could enable the development of novel separations processes, as is required for the transition away from fossil fuel use. Metal-organic capsules, which can selectively bind molecules from mixtures, can provide the foundation for these novel separations processes. Here we report a tetrahedral metal-organic capsule bearing light-responsive diazo moieties around its metal-ion vertices. This capsule can be used to selectively separate progesterone from a mixture of steroids in a process driven by visible light energy. Our process combines biphasic extraction and selective binding of progesterone with the light-driven release of this molecule in purified form. Ultimately, our process might be adapted to the purifications of the many other fine chemical products that are bound selectively by capsules.
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Affiliation(s)
- Amit Ghosh
- Yusuf Hamied Department of
Chemistry, University of Cambridge, Cambridge CB2 1EW, U.K.
| | | | | | - Jonathan R. Nitschke
- Yusuf Hamied Department of
Chemistry, University of Cambridge, Cambridge CB2 1EW, U.K.
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9
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Benchimol E, Tessarolo J, Clever GH. Photoswitchable coordination cages. Nat Chem 2024; 16:13-21. [PMID: 38182764 DOI: 10.1038/s41557-023-01387-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 10/25/2023] [Indexed: 01/07/2024]
Abstract
Stimuli-responsive behaviour is key to the design of smart materials, surfaces, nano-systems and effector molecules, allowing their application as switchable catalysts, molecular transporters, bioimaging probes or caged drugs. Supramolecular chemistry has embraced the widespread integration of photoswitches because of their precise spatiotemporal addressability and waste-free nature. In the vibrant area of discrete metal-mediated self-assembly, however, photoswitches are still rarely employed. Only recently has it been shown that embedding photoswitches into the organic backbones of coordination cages enables control of their host and material properties and thus unlocks the hitherto unexploited dynamic adaptivity of such systems. Here we discuss four cases where triggering ligand-integrated photoswitches leads to (1) control over disassembly/reassembly, (2) bi-stable switching between defined states, (3) interplay with thermal processes in metastable systems and (4) light-fuelled dissipative self-assembly. We highlight first clues concerning the relationship between fundamental photophysics and dynamic assembly equilibria and propose directions for future development.
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Affiliation(s)
- Elie Benchimol
- Department of Chemistry and Chemical Biology, TU Dortmund University, Dortmund, Germany
| | - Jacopo Tessarolo
- Department of Chemistry and Chemical Biology, TU Dortmund University, Dortmund, Germany.
- Department of Chemistry, Chonnam National University, Gwangju, Republic of Korea.
| | - Guido H Clever
- Department of Chemistry and Chemical Biology, TU Dortmund University, Dortmund, Germany.
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10
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Bhattacharjee N, Gao X, Nathani A, Dobscha JR, Pink M, Ito T, Flood AH. Solvent Acts as the Referee in a Match-Up Between Charged and Preorganized Receptors. Chemistry 2023; 29:e202302339. [PMID: 37615829 DOI: 10.1002/chem.202302339] [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: 07/21/2023] [Revised: 08/21/2023] [Accepted: 08/22/2023] [Indexed: 08/25/2023]
Abstract
The prevalence of anion-cation contacts in biomolecular recognition under aqueous conditions suggests that ionic interactions should dominate the binding of anions in solvents across both high and low polarities. Investigations of this idea using titrations in low polarity solvents are impaired by interferences from ion pairing that prevent a clear picture of binding. To address this limitation and test the impact of ion-ion interactions across multiple solvents, we quantified chloride binding to a cationic receptor after accounting for ion pairing. In these studies, we created a chelate receptor using aryl-triazole CH donors and a quinolinium unit that directs its cationic methyl inside the binding pocket. In low-polarity dichloromethane, the 1 : 1 complex (log K1 : 1 ~ 7.3) is more stable than neutral chelates, but fortuitously comparable to a preorganized macrocycle (log K1 : 1 ~ 6.9). Polar acetonitrile and DMSO diminish stabilities of the charged receptor (log K1 : 1 ~ 3.7 and 1.9) but surprisingly 100-fold more than the macrocycle. While both receptors lose stability by dielectric screening of electrostatic stability, the cationic receptor also pays additional costs of organization. Thus even though the charged receptor has stronger binding in apolar solvents, the uncharged receptor has more anion affinity in polar solvents.
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Affiliation(s)
- Nabarupa Bhattacharjee
- Department of Chemistry, Indiana University Bloomington, 800 E. Kirkwood Ave., Bloomington, IN, 47405, USA
| | - Xinfeng Gao
- Department of Chemistry, Indiana University Bloomington, 800 E. Kirkwood Ave., Bloomington, IN, 47405, USA
| | - Akash Nathani
- Department of Chemistry, Kansas State University, 213 CBC Building, 1212 Mid-campus Dr North, Manhattan, KS 66506, USA
| | - James R Dobscha
- Department of Chemistry, Indiana University Bloomington, 800 E. Kirkwood Ave., Bloomington, IN, 47405, USA
| | - Maren Pink
- Department of Chemistry, Indiana University Bloomington, 800 E. Kirkwood Ave., Bloomington, IN, 47405, USA
| | - Takashi Ito
- Department of Chemistry, Kansas State University, 213 CBC Building, 1212 Mid-campus Dr North, Manhattan, KS 66506, USA
| | - Amar H Flood
- Department of Chemistry, Indiana University Bloomington, 800 E. Kirkwood Ave., Bloomington, IN, 47405, USA
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11
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Dorrat JC, Young RJ, Taylor CGP, Tipping MB, Blok AJ, Turner DR, McKay AI, Ovenden S, Ward MD, Dennison GH, Tuck KL. The preservation of sarin and O, O'-diisopropyl fluorophosphate inside coordination cage hosts. Dalton Trans 2023; 52:11802-11814. [PMID: 37272072 DOI: 10.1039/d3dt01378b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The host-guest chemistry of O,O'-diisopropyl fluorophosphate (DFP), a phosphonofluoridate G-series chemical warfare agent simulant, was investigated in the presence of a number of octanuclear cubic coordination cage hosts. The aim was to demonstrate cage-catalysed hydrolysis of DFP at near neutral pH: however, two octanuclear coordination cages, HPEG (containing water-solubilising PEG groups) and HW (containing water-solubilising hydroxymethyl groups), were actually found to increase the lifetime of DFP in aqueous buffer solution (pH 8.7). Crystallographic analysis of DFP with a structurally related host cage revealed that DFP binds to windows in the cage surface, not in the internal cavity. The phosphorus-fluorine bond is directed into the cavity rather than towards the external environment, with the cage/DFP association protecting DFP from hydrolysis. Initial studies with the chemical warfare agent (CWA) sarin (GB) with HPEG cage in a buffered solution also showed a drastically reduced rate of hydrolysis for sarin when bound in the host cage. The ability of these cages to inhibit hydrolysis of these P-F bond containing organophosphorus guests, by encapsulation, may have applications in forensic sample preservation and analysis.
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Affiliation(s)
- Jack C Dorrat
- School of Chemistry, Monash University, Melbourne, VIC, 3800, Australia.
| | - Rosemary J Young
- School of Chemistry, Monash University, Melbourne, VIC, 3800, Australia.
| | | | - Max B Tipping
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.
| | - Andrew J Blok
- CBRN Defence Branch, Sensors and Effectors Division, Defence Science and Technology Group, Fishermans Bend, VIC, 3207, Australia
| | - David R Turner
- School of Chemistry, Monash University, Melbourne, VIC, 3800, Australia.
| | - Alasdair I McKay
- School of Chemistry, Monash University, Melbourne, VIC, 3800, Australia.
| | - Simon Ovenden
- CBRN Defence Branch, Sensors and Effectors Division, Defence Science and Technology Group, Fishermans Bend, VIC, 3207, Australia
| | - Michael D Ward
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.
| | - Genevieve H Dennison
- CBRN Defence Branch, Sensors and Effectors Division, Defence Science and Technology Group, Fishermans Bend, VIC, 3207, Australia
- Weapon Seekers and Tactical Sensors Branch, Sensors and Effectors Division, Defence Science and Technology Group, Edinburgh, SA, 5111, Australia.
| | - Kellie L Tuck
- School of Chemistry, Monash University, Melbourne, VIC, 3800, Australia.
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12
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Pritchard C, Ligorio M, Jackson GD, Gibson MI, Ward MD. Programmable Monodisperse Glyco-Multivalency Using Self-Assembled Coordination Cages as Scaffolds. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 37486195 PMCID: PMC10401570 DOI: 10.1021/acsami.3c08666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
The multivalent presentation of glycans leads to enhanced binding avidity to lectins due to the cluster glycoside effect. Most materials used as scaffolds for multivalent glycan arrays, such as polymers or nanoparticles, have intrinsic dispersity: meaning that in any sample, a range of valencies are presented and it is not possible to determine which fraction(s) are responsible for binding. The intrinsic dispersity of many multivalent glycan scaffolds also limits their reproducibility and predictability. Here we make use of the structurally programmable nature of self-assembled metal coordination cages, with polyhedral metal-ion cores supporting ligand arrays of predictable sizes, to assemble a 16-membered library of perfectly monodisperse glycoclusters displaying valencies from 2 to 24 through a careful choice of ligand/metal combinations. Mono- and trisaccharides are introduced into these clusters, showing that the synthetic route is tolerant of biologically relevant glycans, including sialic acids. The cluster series demonstrates increased binding to a range of lectins as the number of glycans increases. This strategy offers an alternative to current glycomaterials for control of the valency of three-dimensional (3-D) glycan arrays, and may find application across sensing, imaging, and basic biology.
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Affiliation(s)
- Callum Pritchard
- Department of Chemistry, University of Warwick, Coventry CV47AL, U.K
| | - Melissa Ligorio
- Department of Chemistry, University of Warwick, Coventry CV47AL, U.K
| | - Garrett D Jackson
- Department of Chemistry, University of Warwick, Coventry CV47AL, U.K
| | - Matthew I Gibson
- Department of Chemistry, University of Warwick, Coventry CV47AL, U.K
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV47AL, U.K
| | - Michael D Ward
- Department of Chemistry, University of Warwick, Coventry CV47AL, U.K
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13
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Nguyen TN, Nguyen AN, Tran NM, Park IH, Yoo H. Hierarchical packing of racemic metallosupramolecular cages with Ni(II)-based triple-stranded helicate building blocks. IUCRJ 2023; 10:321-328. [PMID: 36995774 PMCID: PMC10161775 DOI: 10.1107/s2052252523002385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 03/12/2023] [Indexed: 05/06/2023]
Abstract
Three novel hierarchical Ni-based metallosupramolecular cages were constructed from nickel ions, pyridine dicarboxylates and isophthalate derivative ligands (the substituents on C5 of isophthalate are methyl, tert-butyl and bromo groups). In every cage, two multinuclear nickel clusters, assembled from four nickel atoms and three pyridine dicarboxylate ligands, are interlinked by three isophthalate-derivative ligands to form a nickel-based triple-stranded helicate (TSH), which then becomes the supramolecular building block for the fabrication of a metallocage. Six homochiral TSH supramolecular building blocks, either left (M)-handed or right (P)-handed, are connected by four linking nickel atoms to generate M6 and P6 discrete racemic cage molecules (M6 - cage with six M-TSHs; P6 - cage with six P-TSHs). The crystal packing of the racemic cages was characterized by single-crystal X-ray diffraction. An additional cobalt-based molecular cage with 5-methylisophthalate bridging ligands was synthesized for host-guest interaction studies. The methyl groups in Co- and Ni-TSH can act as guest units to be accommodated in the cone-shaped metal clusters (host) of an adjacent cage.
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Affiliation(s)
- Thanh Nhan Nguyen
- Department of Materials Science and Chemical Engineering, Hanyang University, Ansan, Gyeonggi-do 15588, Republic of Korea
| | - Anh Ngoc Nguyen
- Department of Materials Science and Chemical Engineering, Hanyang University, Ansan, Gyeonggi-do 15588, Republic of Korea
| | - Ngoc Minh Tran
- Department of Materials Science and Chemical Engineering, Hanyang University, Ansan, Gyeonggi-do 15588, Republic of Korea
| | - In-Hyeok Park
- Graduate School of Analytical Science and Technology (GRAST), Chungnam National University, Daejeon 34134, Republic of Korea
| | - Hyojong Yoo
- Department of Materials Science and Chemical Engineering, Hanyang University, Ansan, Gyeonggi-do 15588, Republic of Korea
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14
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Solea AB, Ward MD. A chemiluminescent lantern: a coordination cage catalysed oxidation of luminol followed by chemiluminescence resonance energy-transfer. Dalton Trans 2023; 52:4456-4461. [PMID: 36917490 PMCID: PMC10071490 DOI: 10.1039/d3dt00689a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
A molecule of luminol bound as guest inside a Co8 coordination cage host undergoes oxidation by H2O2 to generate chemiluminescence by a process in which the Co(II) ions in the cage superstructure activate the H2O2: accordingly the cage not only co-locates the reactants but also acts as a redox partner in the catalysis. The luminescence from oxidation of the cavity-bound luminol can transfer its excitation energy to surface-bound fluorescein molecules in an unusual example of Chemiluminescence Resonance Energy Transfer (CRET).
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Affiliation(s)
- Atena B Solea
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
| | - Michael D Ward
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
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15
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Sarkar M, Hey-Hawkins E, Boomishankar R. Encapsulation Studies on closo-Dicarbadodecaborane Isomers in Neutral Tetrahedral Palladium(II) Cages. Inorg Chem 2023; 62:4035-4042. [PMID: 36857772 DOI: 10.1021/acs.inorgchem.2c04207] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
Abstract
The encapsulation of icosahedral closo-dicarbadodecaborane (o-, m-, and p-carboranes, Cb) as guest molecules at the intrinsic cavities of the three isostructural tetrahedral cages [{Pd3(NiPr)3PO}4(Cl-AN)6] (1), [{Pd3(NiPr)3PO}4(Br-AN)6] (2), and [{Pd3(NiPr)3PO}4(H-AN)6] (3) was studied. The formation of definite host-guest assemblies was probed with mass spectrometry, IR, and NMR spectral analysis. 2D DOSY 1H NMR of the Cb⊂Cage systems showed similar diffusion coefficient (D) values for the host and guest species, signifying the encapsulation of these guests inside the cage assemblies. The hydrodynamic radius (RH) derived from the D values of the host and guest species further confirmed the encapsulation of the Cb isomers at the cage pockets. The single-molecule energy optimization of the host-guest assemblies indicated the preferential binding of o-Cb as a guest inside the cages (1-3). The stabilization of these Cb guests inside these cages was further attributed to various possible nonclassical C-H···X-type interactions.
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Affiliation(s)
- Meghamala Sarkar
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, Dr. Homi Bhabha Road, Pune 411008, India
| | - Evamarie Hey-Hawkins
- Institut für Anorganische Chemie, Fakultät für Chemie und Mineralogie, Universität Leipzig, Johannisallee 29, 04103 Leipzig, Germany
| | - Ramamoorthy Boomishankar
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, Dr. Homi Bhabha Road, Pune 411008, India.,Centre for Energy Science, Indian Institute of Science Education and Research (IISER), Pune, Dr. Homi Bhabha Road, Pune 411008, India
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16
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Schwab JH, Bailey JB, Gembicky M, Stauber JM. Programmable synthesis of well-defined, glycosylated iron(ii) supramolecular assemblies with multivalent protein-binding capabilities. Chem Sci 2023; 14:1018-1026. [PMID: 36755719 PMCID: PMC9890585 DOI: 10.1039/d2sc05689e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 12/20/2022] [Indexed: 12/24/2022] Open
Abstract
Multivalency plays a key role in achieving strong, yet reversible interactions in nature, and provides critical chemical organization in biological recognition processes. Chemists have taken an interest in designing multivalent synthetic assemblies to both better understand the underlying principles governing these interactions, and to build chemical tools that either enhance or prevent such recognition events from occurring in biology. Rationally tailoring synthetic strategies to achieve the high level of chemical control and tunability required to mimic these interactions, however, is challenging. Here, we introduce a systematic and modular synthetic approach to the design of well-defined molecular multivalent protein-binding constructs that allows for control over size, morphology, and valency. A series of supramolecular mono-, bi-, and tetrametallic Fe(ii) complexes featuring a precise display of peripheral saccharides was prepared through coordination-driven self-assembly from simple building blocks. The molecular assemblies are fully characterized, and we present the structural determination of one complex in the series. The mannose and maltose-appended assemblies display strong multivalent binding to model lectin, Concanavalin A (K d values in μM), where the strength of the binding is a direct consequence of the number of saccharide units decorating the molecular periphery. This versatile synthetic strategy provides chemical control while offering an easily accessible approach to examine important design principles governing structure-function relationships germane to biological recognition and binding properties.
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Affiliation(s)
- Jake H. Schwab
- Department of Chemistry and Biochemistry, University of California9500 Gilman Dr, La JollaSan DiegoCAUSA
| | - Jake B. Bailey
- Department of Chemistry and Biochemistry, University of California9500 Gilman Dr, La JollaSan DiegoCAUSA
| | - Milan Gembicky
- Department of Chemistry and Biochemistry, University of California 9500 Gilman Dr, La Jolla San Diego CA USA
| | - Julia M. Stauber
- Department of Chemistry and Biochemistry, University of California9500 Gilman Dr, La JollaSan DiegoCAUSA
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17
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Metal Organic Polygons and Polyhedra: Instabilities and Remedies. INORGANICS 2023. [DOI: 10.3390/inorganics11010036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The field of coordination chemistry has undergone rapid transformation from preparation of monometallic complexes to multimetallic complexes. So far numerous multimetallic coordination complexes have been synthesized. Multimetallic coordination complexes with well-defined architectures are often called as metal organic polygons and polyhedra (MOPs). In recent past, MOPs have received tremendous attention due to their potential applicability in various emerging fields. However, the field of coordination chemistry of MOPs often suffer set back due to the instability of coordination complexes particularly in aqueous environment-mostly by aqueous solvent and atmospheric moisture. Accordingly, the fate of the field does not rely only on the water solubilities of newly synthesized MOPs but very much dependent on their stabilities both in solution and solid state. The present review discusses several methodologies to prepare MOPs and investigates their stabilities under various circumstances. Considering the potential applicability of MOPs in sustainable way, several methodologies (remedies) to enhance the stabilities of MOPs are discussed here.
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18
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Bonsall S, Hubbard S, Jithin U, Anslow J, Todd D, Rowding C, Filarowski T, Duly G, Wilson R, Porter J, Turega S, Haywood-Small S. Water-Soluble Truncated Fatty Acid-Porphyrin Conjugates Provide Photo-Sensitizer Activity for Photodynamic Therapy in Malignant Mesothelioma. Cancers (Basel) 2022; 14:5446. [PMID: 36358864 PMCID: PMC9654571 DOI: 10.3390/cancers14215446] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 10/22/2022] [Accepted: 10/28/2022] [Indexed: 03/07/2024] Open
Abstract
Clinical trials evaluating intrapleural photodynamic therapy (PDT) are ongoing for mesothelioma. Several issues still hinder the development of PDT, such as those related to the inherent properties of photosensitizers. Herein, we report the synthesis, photophysical, and photobiological properties of three porphyrin-based photosensitizers conjugated to truncated fatty acids (C5SHU to C7SHU). Our photosensitizers exhibited excellent water solubility and high PDT efficiency in mesothelioma. As expected, absorption spectroscopy confirmed an increased aggregation as a consequence of extending the fatty acid chain length. In vitro PDT activity was studied using human mesothelioma cell lines (biphasic MSTO-211H cells and epithelioid NCI-H28 cells) alongside a non-malignant mesothelial cell line (MET-5A). The PDT effect of these photosensitizers was initially assessed using the colorimetric WST-8 cell viability assay and the mode of cell death was determined via flow cytometry of Annexin V-FITC/PI-stained cells. Photosensitizers appeared to selectively localize within the non-nuclear compartments of cells before exhibiting high phototoxicity. Both apoptosis and necrosis were induced at 24 and 48 h. As our pentanoic acid-derivatized porphyrin (C5SHU) induced the largest anti-tumor effect in this study, we put this forward as an anti-tumor drug candidate in PDT and photo-imaging diagnosis in mesothelioma.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Sarah Haywood-Small
- Biomolecular Sciences Research Centre, Sheffield Hallam University, City Campus, Howard Street, Sheffield S1 1WB, UK
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19
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Mozaceanu C, Solea AB, Taylor CGP, Sudittapong B, Ward MD. Disentangling contributions to guest binding inside a coordination cage host: analysis of a set of isomeric guests with differing polarities. Dalton Trans 2022; 51:15263-15272. [PMID: 36129351 PMCID: PMC9578013 DOI: 10.1039/d2dt02623f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Binding of a set of three isomeric guests (1,2-, 1,3- and 1,4-dicyanobenzene, abbreviated DCB) inside an octanuclear cubic coordination cage host H (bearing different external substitutents according to solvent used) has been studied in water/dmso (98 : 2) and CD2Cl2. These guests have essentially identical molecular surfaces, volumes and external functional groups to interact with the cage interior surface; but they differ in polarity with dipole moments of ca. 7, 4 and 0 Debye respectively. In CD2Cl2 guest binding is weak but we observe a clear correlation of binding free energy with guest polarity, with 1,4-DCB showing no detectable binding by NMR spectroscopy but 1,2-DCB having −ΔG = 9 kJ mol−1. In water (containing 2% dmso to solubilise the guests) we see the same trend but all binding free energies are much higher due to an additional hydrophobic contribution to binding, with −ΔG varying from 16 kJ mol−1 for 1,4-DCB to 22 kJ mol−1 for 1,4-DCB: again we see an increase associated with guest polarity but the increase in −ΔG per Debye of dipole moment is around half what we observe in CD2Cl2 which we ascribe to the fact the more polar guests will be better solvated in the aqueous solvent. A van't Hoff analysis by variable-temperature NMR showed that the improvement in guest binding in water/dmso is entropy-driven, which suggests that the key factor is not direct electrostatic interactions between a polar guest and the cage surface, but the variation in guest desolvation across the series, with the more polar (and hence more highly solvated) guests having a greater favourable entropy change on desolvation. The three dicyanobenzene isomers have obvious similarities but differ in their dipole moment: effects on binding in a coordination cage host in different solvents are discussed.![]()
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Affiliation(s)
| | - Atena B Solea
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
| | | | - Burin Sudittapong
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
| | - Michael D Ward
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
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20
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Cruz-Nava S, Valencia-Loza SDJ, Percástegui EG. Protection and Transformation of Natural Products within Aqueous Metal–Organic Cages. European J Org Chem 2022. [DOI: 10.1002/ejoc.202200844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Sofía Cruz-Nava
- National Autonomous University of Mexico Faculty of Science: Universidad Nacional Autonoma de Mexico Facultad de Ciencias Institute of Chemistry MEXICO
| | | | - Edmundo Guzmán Percástegui
- Universidad Nacional Autónoma de México: Universidad Nacional Autonoma de Mexico Instituto de Química Instituto de Química at CCIQS UAEM-UNAM MEXICO
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21
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Wang LJ, Bai S, Han YF. Water-Soluble Self-Assembled Cage with Triangular Metal-Metal-Bonded Units Enabling the Sequential Selective Separation of Alkanes and Isomeric Molecules. J Am Chem Soc 2022; 144:16191-16198. [PMID: 35972889 DOI: 10.1021/jacs.2c07586] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The selective separation of structurally similar aliphatic/aromatic hydrocarbons is an essential goal in industrial processes. In this study, we report the synthesis of a water-soluble (Tr2M3)4L4 (Tr = cycloheptatrienyl ring; M = metal; L = organosulfur ligand) molecular cage (1) via self-assembly of the water-soluble acceptor tripalladium sandwich species [(Tr2Pd3)(CH3CN)][NO3]2 and the attachment onto L of solubilizing methoxyethoxy appendants to be utilized in an energy-friendly alternative approach to the separation of structurally similar molecules under ambient conditions. Cage 1, comprising a hydrophobic inner cavity, exhibited good solubility and stability in aqueous media. It also demonstrated excellent performance in the sequential separation of alkanes (C6-C9), xylene, and other disubstituted benzene isomers and cis/trans-decalin.
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Affiliation(s)
- Li-Juan Wang
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, P.R. China
| | - Sha Bai
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, P.R. China
| | - Ying-Feng Han
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, P.R. China
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22
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Solea AB, Sudittapong B, Taylor CGP, Ward MD. Inside or outside the box? Effect of substrate location on coordination-cage based catalysis. Dalton Trans 2022; 51:11277-11285. [PMID: 35791857 PMCID: PMC9344580 DOI: 10.1039/d2dt01713j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 06/30/2022] [Indexed: 01/15/2023]
Abstract
In this work we compare and contrast the hydrolysis of two different aromatic esters using an octanuclear cubic Co8 coordination cage host as the catalyst. Diacetyl fluorescein (DAF) is too large to bind inside the cage cavity, but in aqueous solution it interacts with the exterior surface of the cage via a hydrophobic interaction with K = 1.5(2) × 104 M-1. This is sufficient to bring it into close proximity to the layer of hydroxide ions which also surrounds the 16+ cage surface even at modest pH values, accelerating the hydrolysis of DAF to fluorescein with kcat/kuncat (the rate acceleration for that fraction of DAF in contact with the cage surface in the equilibrium) ≈50. This is far smaller than many known examples of catalysis inside a cage cavity, but at the exterior surface it is potentially general with no cavity-imposed size/shape limitations for guest binding. In contrast 4-nitrophenyl acetate (4NPA) binds inside the cage cavity with K = 3.5(3) × 103 M-1 and as such is surrounded in solution by the hydroxide ions which accumulate around the cage surface. However its hydrolysis is actually inhibited: either because of a geometrically unfavourable geometry of the bound substrate which makes it inaccessible to surface-bound hydroxide, or because the necessary volume expansion/geometry change associated with formation of a tetrahedral intermediate cannot be accommodated inside the cavity. Any 4NPA that is free in solution as part of the equilibrium undergoes catalysed hydrolysis at the cage exterior surface in the same way as DAF, but the effect is limited by the low affinity of 4NPA for the exterior surface. We conclude that exterior-surface catalysis can be effective and potentially general; and that cavity-binding of guests can result in negative, rather than positive, catalysis.
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Affiliation(s)
- Atena B Solea
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
| | - Burin Sudittapong
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
| | | | - Michael D Ward
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
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23
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Abstract
Supramolecular metal–organic cages, a class of molecular containers formed via coordination-driven self-assembly, have attracted sustained attention for their applications in catalysis, due to their structural aesthetics and unique properties. Their inherent confined cavity is considered to be analogous to the binding pocket of enzymes, and the facile tunability of building blocks offers a diverse platform for enzyme mimics to promote organic reactions. This minireview covers the recent progress of supramolecular metal–organic coordination cages for boosting organic reactions as reaction vessels or catalysts. The developments in the utilizations of the metal–organic cages for accelerating the organic reactions, improving the selectivity of the reactions are summarized. In addition, recent developments and successes in tandem or cascade reactions promoted by supramolecular metal–organic cages are discussed.
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24
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Ludden MD, Taylor CGP, Tipping MB, Train JS, Williams NH, Dorrat JC, Tuck KL, Ward MD. Interaction of anions with the surface of a coordination cage in aqueous solution probed by their effect on a cage-catalysed Kemp elimination. Chem Sci 2021; 12:14781-14791. [PMID: 34820094 PMCID: PMC8597839 DOI: 10.1039/d1sc04887b] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 10/25/2021] [Indexed: 11/21/2022] Open
Abstract
An octanuclear M8L12 coordination cage catalyses the Kemp elimination reaction of 5-nitro-1,2-benzisoxazole (NBI) with hydroxide to give 2-cyano-4-nitrophenolate (CNP) as the product. In contrast to the previously-reported very efficient catalysis of the Kemp elimination reaction of unsubstituted benzisoxazole, which involves the substrate binding inside the cage cavity, the catalysed reaction of NBI with hydroxide is slower and occurs at the external surface of the cage, even though NBI can bind inside the cage cavity. The rate of the catalysed reaction is sensitive to the presence of added anions, which bind to the 16+ cage surface, displacing the hydroxide ions from around the cage which are essential reaction partners in the Kemp elimination. Thus we can observe different binding affinities of anions to the surface of the cationic cage in aqueous solution by the extent to which they displace hydroxide and thereby inhibit the catalysed Kemp elimination and slow down the appearance of CNP. For anions with a -1 charge the observed affinity order for binding to the cage surface is consistent with their ease of desolvation and their ordering in the Hofmeister series. With anions that are significantly basic (fluoride, hydrogen carbonate, carboxylates) the accumulation of the anion around the cage surface accelerates the Kemp elimination compared to the background reaction with hydroxide, which we ascribe to the ability of these anions to participate directly in the Kemp elimination. This work provides valuable mechanistic insights into the role of the cage in co-locating the substrate and the anionic reaction partners in a cage-catalysed reaction.
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Affiliation(s)
- Michael D Ludden
- Department of Chemistry, University of Warwick Coventry CV4 7AL UK
| | | | - Max B Tipping
- Department of Chemistry, University of Warwick Coventry CV4 7AL UK
| | - Jennifer S Train
- Department of Chemistry, University of Sheffield Sheffield S3 7HF UK
| | | | - Jack C Dorrat
- School of Chemistry, Monash University Melbourne VIC3800 Australia
| | - Kellie L Tuck
- School of Chemistry, Monash University Melbourne VIC3800 Australia
| | - Michael D Ward
- Department of Chemistry, University of Warwick Coventry CV4 7AL UK
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25
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Abstract
New synthetic routes are presented to derivatives of a (known) M8L12 cubic coordination cage in which a range of different substituents are attached at the C4 position of the pyridyl rings at either end of the bis(pyrazolyl-pyridine) bridging ligands. The substituents are (i) –CN groups (new ligand LCN), (ii) –CH2OCH2–CCH (containing a terminal alkyne) groups (new ligand LCC); and (iii) –(CH2OCH2)3CH2OMe (tri-ethyleneglycol monomethyl ether) groups (new ligand LPEG). The resulting functionalised ligands combine with M2+ ions (particularly Co2+, Ni2+, Cd2+) to give isostructural [M8L12]16+ cage cores bearing 24 external functional groups; the cages based on LCN (with M2+ = Cd2+) and LCC (with M2+ = Ni2+) have been crystallographically characterised. The value of these is twofold: (i) exterior nitrile or alkene substituents can provide a basis for further synthetic opportunities via ‘Click’ reactions allowing in principle a diverse range of functionalisation of the cage exterior surface; (ii) the exterior –(CH2OCH2)3CH2OMe groups substantially increase cage solubility in both water and in organic solvents, allowing binding constants of cavity-binding guests to be measured under an increased range of conditions.
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26
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Ludden MD, Taylor CGP, Ward MD. Orthogonal binding and displacement of different guest types using a coordination cage host with cavity-based and surface-based binding sites. Chem Sci 2021; 12:12640-12650. [PMID: 34703549 PMCID: PMC8494021 DOI: 10.1039/d1sc04272f] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 08/24/2021] [Indexed: 12/13/2022] Open
Abstract
The octanuclear Co(ii) cubic coordination cage system H (or HW if it bears external water-solubilising substituents) has two types of binding site for guests. These are (i) the partially-enclosed central cavity where neutral hydrophobic organic species can bind, and (ii) the six 'portals' in the centres of each of the faces of the cubic cage where anions bind via formation of a network of CH⋯X hydrogen bonds between the anion and CH units on the positively-charged cage surface, as demonstrated by a set of crystal structures. The near-orthogonality of these guest binding modes provides the basis for an unusual dual-probe fluorescence displacement assay in which either a cavity-bound fluorophore (4-methyl-7-amino-coumarin, MAC; λem = 440 nm), or a surface-bound anionic fluorophore (fluorescein, FLU; λem = 515 nm), is displaced and has its emission ‘switched on’ according to whether the analyte under investigation is cavity-binding, surface binding, or a combination of both. A completely orthogonal system is demonstrated based using a Hw/MAC/FLU combination: addition of the anionic analyte ascorbate displaced solely FLU from the cage surface, increasing the 515 nm (green) emission component, whereas addition of a neutral hydrophobic guest such as cyclooctanone displaced solely MAC from the cage central cavity, increasing the 440 nm (blue) emission component. Addition of chloride results in some release of both components, and an intermediate colour change, as chloride is a rare example of a guest that shows both surface-binding and cavity-binding behaviour. Thus we have a colourimetric response based on differing contributions from blue and green emission components in which the specific colour change signals the binding mode of the analyte. Addition of a fixed red emission component from the complex [Ru(bipy)3]2+ (Ru) provides a baseline colour shift of the overall colour of the luminescence closer to neutral, meaning that different types of guest binding result in different colour changes which are easily distinguishable by eye. Orthogonal binding of neutral or anionic fluorophores to the cavity or surface, respectively, of a coordination cage host allows a dual-probe displacement assay which gives a different fluorescence colorimetric response according to where analyte species bind.![]()
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Affiliation(s)
- Michael D Ludden
- Department of Chemistry, University of Warwick Coventry CV4 7AL UK
| | | | - Michael D Ward
- Department of Chemistry, University of Warwick Coventry CV4 7AL UK
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27
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Affiliation(s)
- Edmundo G. Percástegui
- Instituto de Química Universidad Nacional Autónoma de México Ciudad Universitaria Ciudad de México 04510 México
- Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM Carretera Toluca-Atlacomulco km 14.5, Toluca Estado de México 50200 México
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28
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Nguyen BN, Thoburn JD, Grommet AB, Howe DJ, Ronson TK, Ryan HP, Bolliger JL, Nitschke JR. Coordination Cages Selectively Transport Molecular Cargoes Across Liquid Membranes. J Am Chem Soc 2021; 143:12175-12180. [PMID: 34337947 PMCID: PMC8397303 DOI: 10.1021/jacs.1c04799] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Indexed: 12/27/2022]
Abstract
Chemical purifications are critical processes across many industries, requiring 10-15% of humanity's global energy budget. Coordination cages are able to catch and release guest molecules based upon their size and shape, providing a new technological basis for achieving chemical separation. Here, we show that aqueous solutions of FeII4L6 and CoII4L4 cages can be used as liquid membranes. Selective transport of complex hydrocarbons across these membranes enabled the separation of target compounds from mixtures under ambient conditions. The kinetics of cage-mediated cargo transport are governed by guest binding affinity. Using sequential transport across two consecutive membranes, target compounds were isolated from a mixture in a size-selective fashion. The selectivities of both cages thus enabled a two-stage separation process to isolate a single compound from a mixture of physicochemically similar molecules.
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Affiliation(s)
| | - John D. Thoburn
- Randolph-Macon
College, Department of Chemistry, Ashland, Virginia 23005, United States
| | - Angela B. Grommet
- University
of Cambridge, Department of Chemistry, Cambridge CB2 1EW, U.K.
| | - Duncan J. Howe
- University
of Cambridge, Department of Chemistry, Cambridge CB2 1EW, U.K.
| | - Tanya K. Ronson
- University
of Cambridge, Department of Chemistry, Cambridge CB2 1EW, U.K.
| | - Hugh P. Ryan
- University
of Cambridge, Department of Chemistry, Cambridge CB2 1EW, U.K.
| | - Jeanne L. Bolliger
- University
of Cambridge, Department of Chemistry, Cambridge CB2 1EW, U.K.
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29
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Francesconi O, Milanesi F, Nativi C, Roelens S. Molecular Recognition of Disaccharides in Water: Preorganized Macrocyclic or Adaptive Acyclic? Chemistry 2021; 27:10456-10460. [PMID: 33945180 PMCID: PMC8361761 DOI: 10.1002/chem.202101238] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Indexed: 12/02/2022]
Abstract
When facing the dilemma of following a preorganized or adaptive design approach in conceiving the architecture of new biomimetic receptors for carbohydrates, shape-persistent macrocyclic structures were most often chosen to achieve effective recognition of neutral saccharides in water. In contrast, acyclic architectures have seldom been explored, even though potentially simpler and more easily accessible. In this work, comparison of the binding properties of two structurally related diaminocarbazolic receptors, featuring a macrocyclic and an acyclic tweezer-shaped architecture, highlighted the advantages provided by the acyclic receptor in terms of selectivity in the recognition of 1,4-disaccharides of biological interest. Selective recognition of GlcNAc2 , the core fragment of N-glycans exposed on the surface of enveloped viruses, stands as an emblematic example. NMR spectroscopic data and molecular modeling calculations were used to ascertain the differences in binding mode and to shed light on the origin of recognition efficacy and selectivity.
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Affiliation(s)
- Oscar Francesconi
- Department of Chemistry “Ugo Schiff” and INSTMUniversity of FlorencePolo Scientifico e Tecnologico50019Sesto Fiorentino, FirenzeItaly
| | - Francesco Milanesi
- Department of Chemistry “Ugo Schiff” and INSTMUniversity of FlorencePolo Scientifico e Tecnologico50019Sesto Fiorentino, FirenzeItaly
- Magnetic Resonance Center CERMVia L. Sacconi 650019Sesto Fiorentino, FirenzeItaly
| | - Cristina Nativi
- Department of Chemistry “Ugo Schiff” and INSTMUniversity of FlorencePolo Scientifico e Tecnologico50019Sesto Fiorentino, FirenzeItaly
| | - Stefano Roelens
- Department of Chemistry “Ugo Schiff” and INSTMUniversity of FlorencePolo Scientifico e Tecnologico50019Sesto Fiorentino, FirenzeItaly
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30
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31
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32
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Cardenal A, Ramadhar TR. Application of Crystalline Matrices for the Structural Determination of Organic Molecules. ACS CENTRAL SCIENCE 2021; 7:406-414. [PMID: 33791424 PMCID: PMC8006175 DOI: 10.1021/acscentsci.0c01492] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Indexed: 06/12/2023]
Abstract
While single-crystal X-ray diffraction (SC-XRD) is one of the most powerful structural determination techniques for organic molecules, the requirement of obtaining a suitable crystal for analysis limits its applicability, particularly for liquids and amorphous solids. The emergent use of preformed porous crystalline matrices that can absorb organic compounds and stabilize them via host-guest interactions for observation via SC-XRD offers a way to overcome this hindrance. A topical and current discussion of SC-XRD in organic chemistry and the use of preformed matrices for the in crystallo analysis of organic compounds, with a particular focus on the absolute structure determination of chiral molecules, is presented. Preformed crystalline matrices that are covered include metal-organic frameworks (MOFs) as used in the crystalline sponge method, metal-organic polyhedra (MOPs, coordination cages), porous organic materials (POMs)/porous organic molecular crystals (POMCs), and biological scaffolds. An outlook and perspective on the current technology and on its future directions is provided.
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Affiliation(s)
- Ashley
D. Cardenal
- Department of Chemistry, Howard University, Washington, DC 20059, United States
| | - Timothy R. Ramadhar
- Department of Chemistry, Howard University, Washington, DC 20059, United States
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33
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Ludden MD, Ward MD. Outside the box: quantifying interactions of anions with the exterior surface of a cationic coordination cage. Dalton Trans 2021; 50:2782-2791. [PMID: 33566043 DOI: 10.1039/d0dt04211k] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We describe a study of the binding of anions to the surface of an octanuclear coordination cage HW, which carries a 16+ charge, in aqueous solution. Anionic aromatic fluorophores such as fluorescein (and derivatives) and hydroxypyrene tris-sulfonate (HPTS) bind strongly to an extent depending on their charge and hydrophobicity. Job plots indicated binding of up to six such fluorescent anions to HW, implying that one anion can bind to each face of the cubic cage, as previously demonstrated crystallographically with small anions such as halides. The quenching of these fluorophores on association with the cage provides the basis of a fluorescence displacement assay to investigate binding of other anions: addition of analyte (organic or inorganic) anions in titration experiments to an HW/fluorescein combination results in displacement and restoration of the fluorescence from the bound fluorescein, allowing calculation of 1 : 1 binding constants for the HW/anion combinations. Relative binding affinities of simple anions for the cage surface can be approximately rationalised on the basis of ease of desolvation (e.g. F- < Cl- < Br-), electrostatic factors given the 16+ charge on the cage (monoanions < dianions), and extent of hydrophobic surface. The interaction of a di-anionic pH indicator (bromocresol purple) with HW results in a pKa shift, with the surface-bound di-anionic form stabilised by approximately 1 pKa unit compared to the non-bound neutral form due to the charge on the cage.
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Affiliation(s)
- Michael D Ludden
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
| | - Michael D Ward
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
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34
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Escobar L, Ballester P. Molecular Recognition in Water Using Macrocyclic Synthetic Receptors. Chem Rev 2021; 121:2445-2514. [PMID: 33472000 DOI: 10.1021/acs.chemrev.0c00522] [Citation(s) in RCA: 123] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Molecular recognition in water using macrocyclic synthetic receptors constitutes a vibrant and timely research area of supramolecular chemistry. Pioneering examples on the topic date back to the 1980s. The investigated model systems and the results derived from them are key for furthering our understanding of the remarkable properties exhibited by proteins: high binding affinity, superior binding selectivity, and extreme catalytic performance. Dissecting the different effects contributing to the proteins' properties is severely limited owing to its complex nature. Molecular recognition in water is also involved in other appreciated areas such as self-assembly, drug discovery, and supramolecular catalysis. The development of all these research areas entails a deep understanding of the molecular recognition events occurring in aqueous media. In this review, we cover the past three decades of molecular recognition studies of neutral and charged, polar and nonpolar organic substrates and ions using selected artificial receptors soluble in water. We briefly discuss the intermolecular forces involved in the reversible binding of the substrates, as well as the hydrophobic and Hofmeister effects operating in aqueous solution. We examine, from an interdisciplinary perspective, the design and development of effective water-soluble synthetic receptors based on cyclic, oligo-cyclic, and concave-shaped architectures. We also include selected examples of self-assembled water-soluble synthetic receptors. The catalytic performance of some of the presented receptors is also described. The latter process also deals with molecular recognition and energetic stabilization, but instead of binding ground-state species, the targets become elusive counterparts: transition states and other high-energy intermediates.
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Affiliation(s)
- Luis Escobar
- Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST), Av. Països Catalans 16, 43007 Tarragona, Spain.,Departament de Química Analítica i Química Orgánica, Universitat Rovira i Virgili, c/Marcel·lí Domingo 1, 43007 Tarragona, Spain
| | - Pablo Ballester
- Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST), Av. Països Catalans 16, 43007 Tarragona, Spain.,ICREA, Passeig Lluís Companys 23, 08010 Barcelona, Spain
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35
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Percástegui E, Ronson TK, Nitschke JR. Design and Applications of Water-Soluble Coordination Cages. Chem Rev 2020; 120:13480-13544. [PMID: 33238092 PMCID: PMC7760102 DOI: 10.1021/acs.chemrev.0c00672] [Citation(s) in RCA: 238] [Impact Index Per Article: 59.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Indexed: 12/23/2022]
Abstract
Compartmentalization of the aqueous space within a cell is necessary for life. In similar fashion to the nanometer-scale compartments in living systems, synthetic water-soluble coordination cages (WSCCs) can isolate guest molecules and host chemical transformations. Such cages thus show promise in biological, medical, environmental, and industrial domains. This review highlights examples of three-dimensional synthetic WSCCs, offering perspectives so as to enhance their design and applications. Strategies are presented that address key challenges for the preparation of coordination cages that are soluble and stable in water. The peculiarities of guest binding in aqueous media are examined, highlighting amplified binding in water, changing guest properties, and the recognition of specific molecular targets. The properties of WSCC hosts associated with biomedical applications, and their use as vessels to carry out chemical reactions in water, are also presented. These examples sketch a blueprint for the preparation of new metal-organic containers for use in aqueous solution, as well as guidelines for the engineering of new applications in water.
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Affiliation(s)
- Edmundo
G. Percástegui
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United
Kingdom
- Instituto
de Química, Ciudad UniversitariaUniversidad
Nacional Autónoma de México, Ciudad de México 04510, México
- Centro
Conjunto de Investigación en Química Sustentable, UAEM-UNAM, Carretera Toluca-Atlacomulco Km 14.5, Toluca, 50200 Estado de México, México
| | - Tanya K. Ronson
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United
Kingdom
| | - Jonathan R. Nitschke
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United
Kingdom
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36
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Nicholas JD, Chechik V. Characterization of Host-Guest Complexes of Supramolecular Self-Assembled Cages Using EPR Spectroscopy. J Phys Chem B 2020; 124:5646-5653. [PMID: 32520563 DOI: 10.1021/acs.jpcb.0c02599] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Host-guest interactions between nitroxide stable radicals and supramolecular coordination cages were investigated using electron paramagnetic resonance (EPR) spectroscopy in water and acetonitrile. TEMPO showed negligible association with the cages in water, while 4-oxo-TEMPO bound with a strength comparable to that previously reported for related ketones. Carboxylic acid-functionalized nitroxides bound strongly to the acetonitrile-soluble coordination cages. In all cases, host-guest complex formation resulted in significant decreases in the molecular tumbling rate of the guests, with tumbling becoming strongly anisotropic. The polarity of the cage environment in both solvents was found to be intermediate between water and acetonitrile.
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Affiliation(s)
- James D Nicholas
- Department of Chemistry, University of York, Heslington, York YO10 5DD, U.K
| | - Victor Chechik
- Department of Chemistry, University of York, Heslington, York YO10 5DD, U.K
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37
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Interactions of Small-Molecule Guests with Interior and Exterior Surfaces of a Coordination Cage Host. CHEMISTRY 2020. [DOI: 10.3390/chemistry2020031] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Coordination cages are well-known to act as molecular containers that can bind small-molecule guests in their cavity. Such cavity binding is associated with interactions of the guests with the surrounding set of surfaces that define the cavity; a guest that is a good fit for the cavity will have many favourable interactions with the interior surfaces of the host. As cages have exterior as well as interior surfaces, possibilities also exist for ‘guests’ that are not well-bound in the cavity to interact with the exterior surface of the cage where spatial constraints are fewer. In this paper, we report a combined solid-state and solution study using an octanuclear cubic M8L12 coordination cage which illustrates the occurrence of both types of interaction. Firstly, crystallographic studies show that a range of guests bind inside the cavity (either singly or in stacked pairs) and/or interact with the cage exterior surface, depending on their size. Secondly, fluorescence titrations in aqueous solution show how some flexible aromatic disulfides show two separate types of interaction with the cage, having different spectroscopic consequences; we ascribe this to separate interactions with the exterior surface and the interior surface of the host cage with the former having a higher binding constant. Overall, it is clear that the idea of host/guest interactions in molecular containers needs to take more account of external surface interactions as well as the obvious cavity-based binding.
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38
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Hwang SY, Kim D, Lee H, Jung O. Cage Effect on Oxidation of Dimethyl Sulfoxide via Pd
2
L
4
Prolate Spheroids. B KOREAN CHEM SOC 2020. [DOI: 10.1002/bkcs.11999] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Seo Young Hwang
- Department of ChemistryPusan National University Busan 46241 Republic of Korea
| | - Dongwon Kim
- Department of ChemistryPusan National University Busan 46241 Republic of Korea
| | - Haeri Lee
- Department of ChemistryPusan National University Busan 46241 Republic of Korea
| | - Ok‐Sang Jung
- Department of ChemistryPusan National University Busan 46241 Republic of Korea
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39
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Taylor CGP, Metherell AJ, Argent SP, Ashour FM, Williams NH, Ward MD. Coordination-Cage-Catalysed Hydrolysis of Organophosphates: Cavity- or Surface-Based? Chemistry 2020; 26:3065-3073. [PMID: 31774202 PMCID: PMC7079011 DOI: 10.1002/chem.201904708] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Indexed: 12/27/2022]
Abstract
The hydrophobic central cavity of a water-soluble M8 L12 cubic coordination cage can accommodate a range of phospho-diester and phospho-triester guests such as the insecticide "dichlorvos" (2,2-dichlorovinyl dimethyl phosphate) and the chemical warfare agent analogue di(isopropyl) chlorophosphate. The accumulation of hydroxide ions around the cationic cage surface due to ion-pairing in solution generates a high local pH around the cage, resulting in catalysed hydrolysis of the phospho-triester guests. A series of control experiments unexpectedly demonstrates that-in marked contrast to previous cases-it is not necessary for the phospho-triester substrates to be bound inside the cavity for catalysed hydrolysis to occur. This suggests that catalysis can occur on the exterior surface of the cage as well as the interior surface, with the exterior-binding catalysis pathway dominating here because of the small binding constants for these phospho-triester substrates in the cage cavity. These observations suggest that cationic but hydrophobic surfaces could act as quite general catalysts in water by bringing substrates into contact with the surface (via the hydrophobic effect) where there is also a high local concentration of anions (due to ion pairing/electrostatic effects).
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Affiliation(s)
| | | | | | - Fatma M. Ashour
- Department of ChemistryUniversity of SheffieldSheffieldS3 7HFUK
| | | | - Michael D. Ward
- Department of ChemistryUniversity of WarwickCoventryCV4 7ALUK
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40
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Taylor CGP, Argent SP, Ludden MD, Piper JR, Mozaceanu C, Barnett SA, Ward MD. One Guest or Two? A Crystallographic and Solution Study of Guest Binding in a Cubic Coordination Cage. Chemistry 2020; 26:3054-3064. [PMID: 31816132 PMCID: PMC7079040 DOI: 10.1002/chem.201905499] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Indexed: 01/22/2023]
Abstract
A crystallographic investigation of a series of host-guest complexes in which small-molecule organic guests occupy the central cavity of an approximately cubic M8 L12 coordination cage has revealed some unexpected behaviour. Whilst some guests form 1:1 H⋅G complexes as we have seen before, an extensive family of bicyclic guests-including some substituted coumarins and various saturated analogues-form 1:2 H⋅G2 complexes in the solid state, despite the fact that solution titrations are consistent with 1:1 complex formation, and the combined volume of the pair of guests significantly exceeds the Rebek 55±9 % packing for optimal guest binding, with packing coefficients of up to 87 %. Re-examination of solution titration data for guest binding in two cases showed that, although conventional fluorescence titrations are consistent with 1:1 binding model, alternative forms of analysis-Job plot and an NMR titration-at higher concentrations do provide evidence for 1:2 H⋅G2 complex formation. The observation of guests binding in pairs in some cases opens new possibilities for altered reactivity of bound guests, and also highlights the recently articulated difficulties associated with determining stoichiometry of supramolecular complexes in solution.
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Affiliation(s)
| | | | | | - Jerico R. Piper
- Department of ChemistryUniversity of WarwickCoventryCV4 7ALUK
| | | | - Sarah A. Barnett
- Diamond Light Source Ltd., Diamond HouseHarwell Science and Innovation CampusDidcot, OxfordshireOX11 0DEUK
| | - Michael D. Ward
- Department of ChemistryUniversity of WarwickCoventryCV4 7ALUK
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41
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Abstract
The aldol condensation of indane-1,3-dione (ID) to give ‘bindone’ in water is catalysed by an M8L12 cubic coordination cage (Hw). The absolute rate of reaction is slow under weakly acidic conditions (pH 3–4), but in the absence of a catalyst it is undetectable. In water, the binding constant of ID in the cavity of Hw is ca. 2.4 (±1.2) × 103 M−1, giving a ∆G for the binding of −19.3 (±1.2) kJ mol−1. The crystal structure of the complex revealed the presence of two molecules of the guest ID stacked inside the cavity, giving a packing coefficient of 74% as well as another molecule hydrogen-bonded to the cage’s exterior surface. We suggest that the catalysis occurs due to the stabilisation of the enolate anion of ID by the 16+ surface of the cage, which also attracts molecules of neutral ID to the surface because of its hydrophobicity. The cage, therefore, brings together neutral ID and its enolate anion via two different interactions to catalyse the reaction, which—as the control experiments show—occurs at the exterior surface of the cage and not inside the cage cavity.
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42
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Hudspith L, Shmam F, Dalton CF, Princivalle A, Turega SM. Neurotransmitter selection by monoamine oxidase isoforms, dissected in terms of functional groups by mixed double mutant cycles. Org Biomol Chem 2019; 17:8871-8877. [PMID: 31556440 DOI: 10.1039/c9ob01558b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Double mutant cycles were constructed using neurotransmitters and synthetic substrates that measure their selective binding to one monoamine oxidase (MAO) enzyme isoform over another as a function of structural change. This work measures a reduction in selectivity for the MAOB isoform of 3 to 9.5 kJ mol-1 upon the addition of hydroxy functional groups to a phenethylamine scaffold. Replacement of hydroxy functional groups on the phenethylamine scaffold by hydrophobic substituents measures an increase in selectivity for MAOB of -1.1 to -6.9 kJ mol-1. The strategies presented here can be applied to the development of competitive reversible inhibitors of MAO enzymes and other targets with structurally related isoforms.
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Affiliation(s)
- L Hudspith
- Biomolecular Sciences Research Centre, Sheffield Hallam University, Howard Street, Sheffield, S1 1WB, UK.
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43
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Plajer AJ, Percástegui EG, Santella M, Rizzuto FJ, Gan Q, Laursen BW, Nitschke JR. Fluorometric Recognition of Nucleotides within a Water‐Soluble Tetrahedral Capsule. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201814149] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Alex J. Plajer
- Department of ChemistryUniversity of Cambridge Lensfield Road Cambridge CB2 1EW UK
| | | | - Marco Santella
- Department of Chemistry & Nano-Science CenterUniversity of Copenhagen Universitetsparken 5 2100 Copenhagen Denmark
| | - Felix J. Rizzuto
- Department of ChemistryUniversity of Cambridge Lensfield Road Cambridge CB2 1EW UK
| | - Quan Gan
- Department of ChemistryUniversity of Cambridge Lensfield Road Cambridge CB2 1EW UK
| | - Bo W. Laursen
- Department of Chemistry & Nano-Science CenterUniversity of Copenhagen Universitetsparken 5 2100 Copenhagen Denmark
| | - Jonathan R. Nitschke
- Department of ChemistryUniversity of Cambridge Lensfield Road Cambridge CB2 1EW UK
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44
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Peñuelas-Haro G, Ballester P. Efficient hydrogen bonding recognition in water using aryl-extended calix[4]pyrrole receptors. Chem Sci 2019; 10:2413-2423. [PMID: 30931096 PMCID: PMC6399678 DOI: 10.1039/c8sc05034a] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 12/19/2018] [Indexed: 12/25/2022] Open
Abstract
We describe the synthesis of four water-soluble aryl-extended calix[4]pyrrole receptors and report their binding properties with multiple neutral polar guests in water. The prepared receptors present different functionalization at their upper rims and have in common the placement of water solubilizing pyridinium groups at their lower rims. We investigate the interaction of the receptors with a guest series in water solution using 1H NMR titrations and ITC experiments. Despite the known competitive nature of water for hydrogen-bonding interactions, we demonstrate the formation of thermodynamically highly stable 1 : 1 inclusion complexes stabilized by hydrogen-bonding interactions. We show that increasing the hydrogen-bond acceptor character of the guest has a positive impact on binding affinity. This result suggests that the receptor's cavity is indeed a better hydrogen-bond donor to interact with the guests than water molecules. We also assess the important contribution of the hydrophobic effect to binding by comparing the binding affinities of analogous inclusion complexes in water and chloroform solutions. The more polar guests are bound with similar affinities in the two solvents. We compare the binding properties of the different complexes in order to derive general trends.
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Affiliation(s)
- G Peñuelas-Haro
- Institute of Chemical Research of Catalonia (ICIQ) , The Barcelona Institute of Science and Technology (BIST) , Av. Països Catalans, 16 , 43007-Tarragona , Spain .
- Universitat Rovira i Virgili , Departament de Química Analítica i Química Orgànica , c/Marcel·li Domingo, 1 , 43007-Tarragona , Spain
| | - P Ballester
- Institute of Chemical Research of Catalonia (ICIQ) , The Barcelona Institute of Science and Technology (BIST) , Av. Països Catalans, 16 , 43007-Tarragona , Spain .
- ICREA , Pg. Lluís Companys, 23 , 08018-Barcelona , Spain
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45
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Plajer AJ, Percástegui EG, Santella M, Rizzuto FJ, Gan Q, Laursen BW, Nitschke JR. Fluorometric Recognition of Nucleotides within a Water-Soluble Tetrahedral Capsule. Angew Chem Int Ed Engl 2019; 58:4200-4204. [PMID: 30666756 DOI: 10.1002/anie.201814149] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Indexed: 12/11/2022]
Abstract
The design of aqueous probes and binders for complex, biologically relevant anions presents a key challenge in supramolecular chemistry. Herein, a tetrahedral assembly with cationic faces and corners is reported that is capable of discriminating between anionic and neutral guests in water. Electrostatic repulsion between subcomponents can be overcome by the addition of an anionic template, or generating a robust covalent framework by incorporating tris(2-aminoethyl)amine (TREN). The resultant TREN-capped, water-soluble, fluorescent cage binds mono- and poly-phosphoric esters, including nucleotides. Its covalent skeleton renders it stable at micromolar concentrations in water, enabling the fluorometric detection of biologically relevant guests in an aqueous environment. Selective supramolecular encapsulants, such as 1, could enable new sensing applications, such as recognition of toxins and drugs, under biological conditions.
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Affiliation(s)
- Alex J Plajer
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Edmundo G Percástegui
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Marco Santella
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Felix J Rizzuto
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Quan Gan
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Bo W Laursen
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Jonathan R Nitschke
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
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46
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Train JS, Wragg AB, Auty AJ, Metherell AJ, Chekulaev D, Taylor CGP, Argent SP, Weinstein JA, Ward MD. Photophysics of Cage/Guest Assemblies: Photoinduced Electron Transfer between a Coordination Cage Containing Osmium(II) Luminophores, and Electron-Deficient Bound Guests in the Central Cavity. Inorg Chem 2019; 58:2386-2396. [DOI: 10.1021/acs.inorgchem.8b02860] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Jennifer S. Train
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Ashley B. Wragg
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Alexander J. Auty
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | | | - Dimitri Chekulaev
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | | | - Stephen P. Argent
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | | | - Michael D. Ward
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
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47
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Escobar L, Ballester P. Quantification of the hydrophobic effect using water-soluble super aryl-extended calix[4]pyrroles. Org Chem Front 2019. [DOI: 10.1039/c9qo00171a] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the quantification of the hydrophobic effect using a model system based on water-soluble super aryl-extended calix[4]pyrrole receptors and a series of pyridyl N-oxide derivatives, bearing a non-polar para-substituent, as guests.
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Affiliation(s)
- Luis Escobar
- Institute of Chemical Research of Catalonia (ICIQ)
- The Barcelona Institute of Science and Technology (BIST)
- Tarragona
- Spain
- Universitat Rovira i Virgili
| | - Pablo Ballester
- Institute of Chemical Research of Catalonia (ICIQ)
- The Barcelona Institute of Science and Technology (BIST)
- Tarragona
- Spain
- ICREA
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48
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Zhao L, Jing X, Li X, Guo X, Zeng L, He C, Duan C. Catalytic properties of chemical transformation within the confined pockets of Werner-type capsules. Coord Chem Rev 2019. [DOI: 10.1016/j.ccr.2017.11.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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49
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Zhang Y, Harman DG, Avdeev M, Karatchevtseva I. Cu(II) ion directed self-assembly of a Y8/Cu6 heterometallic coordination cage via an Y(III) metalloligand. Inorganica Chim Acta 2019. [DOI: 10.1016/j.ica.2018.10.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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50
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Percástegui EG, Mosquera J, Ronson TK, Plajer AJ, Kieffer M, Nitschke JR. Waterproof architectures through subcomponent self-assembly. Chem Sci 2018; 10:2006-2018. [PMID: 30881630 PMCID: PMC6385555 DOI: 10.1039/c8sc05085f] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 12/12/2018] [Indexed: 11/21/2022] Open
Abstract
Construction of metal–organic containers that are soluble and stable in water can be challenging – we present diverse strategies that allow the synthesis of kinetically robust water-soluble architectures via subcomponent self-assembly.
Metal–organic containers are readily prepared through self-assembly, but achieving solubility and stability in water remains challenging due to ligand insolubility and the reversible nature of the self-assembly process. Here we have developed conditions for preparing a broad range of architectures that are both soluble and kinetically stable in water through metal(ii)-templated (MII = CoII, NiII, ZnII, CdII) subcomponent self-assembly. Although these structures are composed of hydrophobic and poorly-soluble subcomponents, sulfate counterions render them water-soluble, and they remain intact indefinitely in aqueous solution. Two strategies are presented. Firstly, stability increased with metal–ligand bond strength, maximising when NiII was used as a template. Architectures that disassembled when CoII, ZnII and CdII templates were employed could be directly prepared from NiSO4 in water. Secondly, a higher density of connections between metals and ligands within a structure, considering both ligand topicity and degree of metal chelation, led to increased stability. When tritopic amines were used to build highly chelating ligands around ZnII and CdII templates, cryptate-like water-soluble structures were formed using these labile ions. Our synthetic platform provides a unified understanding of the elements of aqueous stability, allowing predictions of the stability of metal–organic cages that have not yet been prepared.
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Affiliation(s)
| | - Jesús Mosquera
- Department of Chemistry , University of Cambridge , Lensfield Road , CB2 1EW , UK .
| | - Tanya K Ronson
- Department of Chemistry , University of Cambridge , Lensfield Road , CB2 1EW , UK .
| | - Alex J Plajer
- Department of Chemistry , University of Cambridge , Lensfield Road , CB2 1EW , UK .
| | - Marion Kieffer
- Department of Chemistry , University of Cambridge , Lensfield Road , CB2 1EW , UK .
| | - Jonathan R Nitschke
- Department of Chemistry , University of Cambridge , Lensfield Road , CB2 1EW , UK .
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