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Sun PB, Pomfret MN, Elardo MJ, Suresh A, Rentería-Gómez Á, Lalisse RF, Keating S, Chen C, Hilburg SL, Chakma P, Wu Y, Bell RC, Rowan SJ, Gutierrez O, Golder MR. Molecular Ball Joints: Mechanochemical Perturbation of Bullvalene Hardy-Cope Rearrangements in Polymer Networks. J Am Chem Soc 2024; 146:19229-19238. [PMID: 38961828 DOI: 10.1021/jacs.4c04401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/05/2024]
Abstract
The solution-state fluxional behavior of bullvalene has fascinated physical organic and supramolecular chemists alike. Little effort, however, has been put into investigating bullvalene applications in bulk, partially due to difficulties in characterizing such dynamic systems. To address this knowledge gap, we herein probe whether bullvalene Hardy-Cope rearrangements can be mechanically perturbed in bulk polymer networks. We use dynamic mechanical analysis to demonstrate that the activation barrier to the glass transition process is significantly elevated for bullvalene-containing materials relative to "static" control networks. Furthermore, bullvalene rearrangements can be mechanically perturbed at low temperatures in the glassy region; such behavior facilitates energy dissipation (i.e., increased hysteresis energy) and polymer chain alignment to stiffen the material (i.e., increased Young's modulus) under load. Computational simulations corroborate our work that showcases bullvalene as a reversible "low-force" covalent mechanophore in the modulation of viscoelastic behavior.
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Affiliation(s)
- Peiguan B Sun
- Department of Chemistry and Molecular Engineering & Science Institute, University of Washington, Seattle, Washington 98115, United States
| | - Meredith N Pomfret
- Department of Chemistry and Molecular Engineering & Science Institute, University of Washington, Seattle, Washington 98115, United States
| | - Matthew J Elardo
- Department of Chemistry and Molecular Engineering & Science Institute, University of Washington, Seattle, Washington 98115, United States
| | - Adhya Suresh
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Ángel Rentería-Gómez
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Remy F Lalisse
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Sheila Keating
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Chuqiao Chen
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Shayna L Hilburg
- Department of Chemical Engineering, University of Washington, Seattle, Washington 98115, United States
| | - Progyateg Chakma
- Department of Chemistry and Molecular Engineering & Science Institute, University of Washington, Seattle, Washington 98115, United States
| | - Yunze Wu
- Department of Chemistry and Molecular Engineering & Science Institute, University of Washington, Seattle, Washington 98115, United States
| | - Rowina C Bell
- Department of Chemistry and Molecular Engineering & Science Institute, University of Washington, Seattle, Washington 98115, United States
| | - Stuart J Rowan
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
- Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Osvaldo Gutierrez
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Matthew R Golder
- Department of Chemistry and Molecular Engineering & Science Institute, University of Washington, Seattle, Washington 98115, United States
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2
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Sanchez A, Gonzalez VM, Sakamoto J, Gurajapu A, Maimone TJ. Modular, Enantioselective Entry into Polysubstituted Shapeshifting Molecules. J Am Chem Soc 2024; 146:17573-17579. [PMID: 38901002 DOI: 10.1021/jacs.4c03323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2024]
Abstract
Dynamic, shapeshifting hydrocarbons have emerged as enabling frameworks across drug discovery, materials science, and catalysis. Their employment, however, is often hampered by a lack of efficient synthetic methods for their preparation. Herein, we report a unified, concise, and modular synthesis of enantioenriched shapeshifting hydrocarbons (barbaralones and bullvalones) and multisubstituted bullvalenes, leveraging mild photochemical and base-induced rearrangements.
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Affiliation(s)
- Andre Sanchez
- Department of Chemistry, University of California-Berkeley, 826 Latimer Hall, Berkeley, California, 94720, United States
| | - Vanessa M Gonzalez
- Department of Chemistry, University of California-Berkeley, 826 Latimer Hall, Berkeley, California, 94720, United States
| | - Jukiya Sakamoto
- Department of Chemistry, University of California-Berkeley, 826 Latimer Hall, Berkeley, California, 94720, United States
| | - Anjali Gurajapu
- Department of Chemistry, University of California-Berkeley, 826 Latimer Hall, Berkeley, California, 94720, United States
| | - Thomas J Maimone
- Department of Chemistry, University of California-Berkeley, 826 Latimer Hall, Berkeley, California, 94720, United States
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3
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Dohmen C, Paululat T, Ihmels H. Reversible Restrain and Release of the Dynamic Valence Isomerization in a Shape-shifting Bullvalene by Complex Formation. Chemistry 2024; 30:e202304311. [PMID: 38275100 DOI: 10.1002/chem.202304311] [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: 12/24/2023] [Revised: 01/25/2024] [Accepted: 01/26/2024] [Indexed: 01/27/2024]
Abstract
In search for structural features that enable the control of the valence isomerization of the fluxional bullvalene, a bullvalene-bis(harmane) conjugate is identified that acts as chelating ligand in complexes with metal ions. Spectrometric titrations show that this ligand forms 1 : 1 complexes with Ag+, Cu+, Cu2+, and Zn2+. Most importantly, detailed NMR-spectroscopic analysis at different temperatures reveals that the complexation with Ag+ strongly affects the dynamic isomerization of the bullvalene unit of the ligand such that only one predominant valence isomer is formed, even at 5 °C. Detailed 1H-NMR-spectroscopic studies disclose an increased barrier (~11 kJ mol-1) of the Cope rearrangement. Furthermore, the addition of hexacyclene displaces the Ag+ from the complex, so that the valence isomerization is accelerated and an equilibrium with two predominant isomers is formed. In turn, repeated addition of Ag+ regains the complex with the restrained isomerization of the bullvalene unit. This method to control the valence isomerism by straightforward chemical stimuli may be used to simplify structural analysis at elevated temperatures, i. e. a feature not available so far with bullvalenes, and it may be employed as functional element in dynamic supramolecular assemblies.
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Affiliation(s)
- Christoph Dohmen
- Department of Chemistry-Biology, and Center of Micro-and Nanochemistry and (Bio)Technology (Cμ), University of Siegen, Adolf-Reichwein-Str. 2, 57068, Siegen, Germany
| | - Thomas Paululat
- Department of Chemistry-Biology, and Center of Micro-and Nanochemistry and (Bio)Technology (Cμ), University of Siegen, Adolf-Reichwein-Str. 2, 57068, Siegen, Germany
| | - Heiko Ihmels
- Department of Chemistry-Biology, and Center of Micro-and Nanochemistry and (Bio)Technology (Cμ), University of Siegen, Adolf-Reichwein-Str. 2, 57068, Siegen, Germany
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4
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Reimers JR, Li T, Birvé AP, Yang L, Aragonès AC, Fallon T, Kosov DS, Darwish N. Controlling piezoresistance in single molecules through the isomerisation of bullvalenes. Nat Commun 2023; 14:6089. [PMID: 37789027 PMCID: PMC10547723 DOI: 10.1038/s41467-023-41674-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 09/06/2023] [Indexed: 10/05/2023] Open
Abstract
Nanoscale electro-mechanical systems (NEMS) displaying piezoresistance offer unique measurement opportunities at the sub-cellular level, in detectors and sensors, and in emerging generations of integrated electronic devices. Here, we show a single-molecule NEMS piezoresistor that operates utilising constitutional and conformational isomerisation of individual diaryl-bullvalene molecules and can be switched at 850 Hz. Observations are made using scanning tunnelling microscopy break junction (STMBJ) techniques to characterise piezoresistance, combined with blinking (current-time) experiments that follow single-molecule reactions in real time. A kinetic Monte Carlo methodology (KMC) is developed to simulate isomerisation on the experimental timescale, parameterised using density-functional theory (DFT) combined with non-equilibrium Green's function (NEGF) calculations. Results indicate that piezoresistance is controlled by both constitutional and conformational isomerisation, occurring at rates that are either fast (equilibrium) or slow (non-equilibrium) compared to the experimental timescale. Two different types of STMBJ traces are observed, one typical of traditional experiments that are interpreted in terms of intramolecular isomerisation occurring on stable tipped-shaped metal-contact junctions, and another attributed to arise from junction‒interface restructuring induced by bullvalene isomerisation.
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Affiliation(s)
- Jeffrey R Reimers
- International Centre for Quantum and Molecular Structures and the Department of Physics, Shanghai University, Shanghai, 200444, China.
- School of Mathematical and Physical Sciences, University of Technology Sydney, Sydney, NSW, 2007, Australia.
| | - Tiexin Li
- School of Molecular and Life Sciences, Curtin University, Bentley, WA, 6102, Australia
| | - André P Birvé
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW, 2308, Australia
| | - Likun Yang
- International Centre for Quantum and Molecular Structures and the Department of Physics, Shanghai University, Shanghai, 200444, China
| | - Albert C Aragonès
- Department of Materials Science and Physical Chemistry, University of Barcelona, Marti i Franquès 1, 08028, Barcelona, Catalonia, Spain
- Institute of Theoretical and Computational Chemistry, University of Barcelona, Diagonal 645, 08028, Barcelona, Catalonia, Spain
| | - Thomas Fallon
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW, 2308, Australia.
| | - Daniel S Kosov
- College of Science and Engineering, James Cook University, Townsville, QLD, 4811, Australia.
| | - Nadim Darwish
- School of Molecular and Life Sciences, Curtin University, Bentley, WA, 6102, Australia.
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5
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Ottonello A, Wyllie JA, Yahiaoui O, Sun S, Koelln RA, Homer JA, Johnson RM, Murray E, Williams P, Bolla JR, Robinson CV, Fallon T, Soares da Costa TP, Moses JE. Shapeshifting bullvalene-linked vancomycin dimers as effective antibiotics against multidrug-resistant gram-positive bacteria. Proc Natl Acad Sci U S A 2023; 120:e2208737120. [PMID: 37011186 PMCID: PMC10104512 DOI: 10.1073/pnas.2208737120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 02/24/2023] [Indexed: 04/05/2023] Open
Abstract
The alarming rise in superbugs that are resistant to drugs of last resort, including vancomycin-resistant enterococci and staphylococci, has become a significant global health hazard. Here, we report the click chemistry synthesis of an unprecedented class of shapeshifting vancomycin dimers (SVDs) that display potent activity against bacteria that are resistant to the parent drug, including the ESKAPE pathogens, vancomycin-resistant Enterococcus (VRE), methicillin-resistant Staphylococcus aureus (MRSA), as well as vancomycin-resistant S. aureus (VRSA). The shapeshifting modality of the dimers is powered by a triazole-linked bullvalene core, exploiting the dynamic covalent rearrangements of the fluxional carbon cage and creating ligands with the capacity to inhibit bacterial cell wall biosynthesis. The new shapeshifting antibiotics are not disadvantaged by the common mechanism of vancomycin resistance resulting from the alteration of the C-terminal dipeptide with the corresponding d-Ala-d-Lac depsipeptide. Further, evidence suggests that the shapeshifting ligands destabilize the complex formed between the flippase MurJ and lipid II, implying the potential for a new mode of action for polyvalent glycopeptides. The SVDs show little propensity for acquired resistance by enterococci, suggesting that this new class of shapeshifting antibiotic will display durable antimicrobial activity not prone to rapidly acquired clinical resistance.
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Affiliation(s)
- Alessandra Ottonello
- La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC3086, Australia
| | - Jessica A. Wyllie
- La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC3086, Australia
| | - Oussama Yahiaoui
- Department of Chemistry, School of Physical Sciences, The University of Adelaide, Adelaide, SA5005, Australia
| | - Shoujun Sun
- Cancer Center, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY11724
| | - Rebecca A. Koelln
- Cancer Center, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY11724
| | - Joshua A. Homer
- Cancer Center, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY11724
| | - Robert M. Johnson
- Cancer Center, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY11724
| | - Ewan Murray
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, University Park, NottinghamNG7 2RD, U.K.
| | - Paul Williams
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, University Park, NottinghamNG7 2RD, U.K.
| | - Jani R. Bolla
- Department of Biology, University of Oxford, OxfordOX1 3RB, U.K.
- The Kavli Institute for Nanoscience Discovery, University of Oxford, OxfordOX1 3QU, U.K.
| | - Carol V. Robinson
- The Kavli Institute for Nanoscience Discovery, University of Oxford, OxfordOX1 3QU, U.K.
- Physical and Theoretical Chemistry Laboratory, University of Oxford, OxfordOX1 3QZ, U.K.
| | - Thomas Fallon
- Department of Chemistry, School of Physical Sciences, The University of Adelaide, Adelaide, SA5005, Australia
| | | | - John E. Moses
- Cancer Center, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY11724
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6
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Tsukada T, Shoji Y, Takenouchi K, Taka H, Fukushima T. A carbon-functionality-appended diborylacetylene available for a component of organic synthesis and OLEDs. Chem Commun (Camb) 2022; 58:4973-4976. [PMID: 35373797 DOI: 10.1039/d2cc01159j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present new 1,2-diborylacetylene derivatives with planar 9-oxa-10-boraanthracene termini, which display excellent stability to allow usual handling and even thermal evaporation for the preparation of thin films for OLEDs, and also undergo typical reactions of alkynes such as the Diels-Alder reaction.
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Affiliation(s)
- Tetsuyoshi Tsukada
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan. .,Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
| | - Yoshiaki Shoji
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan. .,Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
| | - Kumiko Takenouchi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
| | - Hideo Taka
- Konica Minolta, Ishikawa-cho, Hachioji, Tokyo 192-8505, Japan
| | - Takanori Fukushima
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan. .,Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
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7
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Birvé AP, Patel HD, Price JR, Bloch WM, Fallon T. Guest‐Dependent Isomer Convergence of a Permanently Fluxional Coordination Cage. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202115468] [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)
- André P. Birvé
- Department of Chemistry University of Adelaide Adelaide 5005 Australia
| | - Harshal D. Patel
- Department of Chemistry University of Adelaide Adelaide 5005 Australia
| | - Jason R. Price
- ANSTO Australian Synchrotron 800 Blackburn Road Clayton Vic 3168 Australia
| | - Witold M. Bloch
- Department of Chemistry University of Adelaide Adelaide 5005 Australia
| | - Thomas Fallon
- Department of Chemistry University of Adelaide Adelaide 5005 Australia
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8
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Shapeshifting radicals. Chem Phys 2022. [DOI: 10.1016/j.chemphys.2021.111373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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9
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Sobie KM, Albritton M, Yang Y, Alves MM, Roitberg A, Grenning AJ. Construction of vicinal 4°/3°-carbons via reductive Cope rearrangement. Chem Sci 2022; 13:1951-1956. [PMID: 35308853 PMCID: PMC8848919 DOI: 10.1039/d1sc06307c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 01/20/2022] [Indexed: 11/21/2022] Open
Abstract
Herein reported is a strategy for constructing vicinal 4°/3° carbons via reductive Cope rearrangement. Substrates have been designed which exhibit Cope rearrangement kinetic barriers of ∼23 kcal mol−1 with isoenergetic favorability (ΔG ∼ 0). These fluxional/shape-shifting molecules can be driven forward by chemoselective reduction to useful polyfunctionalized building blocks. Herein reported is a strategy for constructing vicinal 4°/3° carbons via reductive Cope rearrangement.![]()
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Affiliation(s)
- Kristin M Sobie
- Department of Chemistry, University of Florida PO Box 117200 Gainesville FL 32611 USA
| | - Matthew Albritton
- Department of Chemistry, University of Florida PO Box 117200 Gainesville FL 32611 USA
| | - Yinuo Yang
- Department of Chemistry, University of Florida PO Box 117200 Gainesville FL 32611 USA
| | - Mariana M Alves
- Department of Chemistry, University of Florida PO Box 117200 Gainesville FL 32611 USA
| | - Adrian Roitberg
- Department of Chemistry, University of Florida PO Box 117200 Gainesville FL 32611 USA
| | - Alexander J Grenning
- Department of Chemistry, University of Florida PO Box 117200 Gainesville FL 32611 USA
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10
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Patel HD, Gaggl S, Pašteka LF, Fallon T. Ambimodal Pericyclic Rearrangements of Dialkenyl-Bullvalenes Give Tetrahydro-1,8-ethenoheptalenes. Org Lett 2021; 24:319-323. [PMID: 34898219 DOI: 10.1021/acs.orglett.1c03984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The fluxional structure of bullvalene is expanded by the discovery of a [5,5]-sigmatropic rearrangement of dialkenyl substituted derivatives. This gives rise to tetrahydro-1,8-ethenoheptalenes (THEH), representing the first examples of this tricyclic scaffold. Variation of the substitution pattern alters the product distribution, including one thermodynamically balanced between THEH and bullvalene isomers. DFT calculations are used to explore the thermodynamic landscape and reaction mechanism revealing a pretransition state bifurcation leading to a concerted ambimodal rearrangement pathway.
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Affiliation(s)
- Harshal D Patel
- Department of Chemistry, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Sebastian Gaggl
- Department of Chemistry, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Lukáš F Pašteka
- Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences, Comenius University, Ilkovičova 6, 842 15 Bratislava, Slovakia
| | - Thomas Fallon
- Department of Chemistry, The University of Adelaide, Adelaide, SA 5005, Australia
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11
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Fallon T, Birve A, Patel HD, Price JR, Bloch WM. Guest-Dependent Isomer Convergence of a Permanently Fluxional Coordination Cage. Angew Chem Int Ed Engl 2021; 61:e202115468. [PMID: 34854191 PMCID: PMC9303423 DOI: 10.1002/anie.202115468] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Indexed: 11/09/2022]
Abstract
A fluxional bis-monodentate ligand, based on the archetypal shape-shifting molecule bullvalene, self-assembles with M2+ (M = Pd2+ or Pt2+) to produce a highly complex ensemble of permanently fluxional coordination cages. Metal-mediated self-assembly selects for an M2L4 architecture while maintaining shape-shifting ligand complexity. A second level of simplification is achieved with guest-exchange; the binding of halides within the M2L4 cage mixture results in a convergence to a cage species with all four ligands present as the "B isomer". Within this confine, the reaction graph of the bullvalene is greatly restricted, but gives rise to a mixture of 38 possible diastereoisomers in rapid exchange. X-ray crystallography reveals a preference for an achiral form consisting of both ligand enantiomers. Through a combination of NMR spectroscopy and DFT calculations, we elucidate the restricted isomerisation pathway of the permanently fluxional M2L4 assembly.
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Affiliation(s)
- Thomas Fallon
- The University of Adelaide Adelaide Medical School, Department of Chemistry, Badger Laboratories, North Terrace, Adelaide, 5000, Adelaide, AUSTRALIA
| | - Andre Birve
- The University of Adelaide, Department of Chemistry, AUSTRALIA
| | | | - Jason R Price
- Australian Nuclear Science and Technology Organisation, Australian Synchrotron, AUSTRALIA
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Shadfar Z, Yahiaoui O, Collier TA, Fallon T, Allison JR. Illustration of a computational pipeline for evaluating cyclodextrin host-guest complex formation through conformational capture of bullvalene. J Chem Phys 2021; 154:154105. [PMID: 33887942 DOI: 10.1063/5.0045115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Cyclodextrins have a diverse range of applications, including as supramolecular hosts, as enzyme active-site analogs, in improving drug solubility and delivery, and in molecular selection. We have investigated their ability to form stable complexes with bullvalenes, unusual organic cage molecules that spontaneously interconvert between numerous degenerate isomers. The shape-shifting nature of substituted bullvalenes raises the potential for dynamic adaptive binding to biological targets. We tested whether β- and γ-cyclodextrins can capture particular bullvalene isomers and whether the preferred binding mode(s) differ between isomers. We first applied our computational host-guest interaction potential energy profiling to determine the best binding mode(s) of unsubstituted bullvalene and each isomer of methylenehydroxybullvalene to β- and γ-cyclodextrin. Subsequent molecular dynamics simulations of the predicted host-guest complexes showed that while unsubstituted bullvalene has a single, albeit ill-defined, binding mode with either cyclodextrin, each isomer of methylenehydroxybullvalene has two possible modes of binding to β-cyclodextrin but only a single, nebulous mode of binding to γ-cyclodextrin. Experimental determination of the binding free energy of each methylenehydroxybullvalene-cyclodextrin complex showed that methylenehydroxybullvalene is more likely to bind to β-cyclodextrin than to γ-cyclodextrin, despite its smaller cavity. Together, our results suggest that β-cyclodextrin, but not γ-cyclodextrin, shows promise for conformational capture of mono-substituted bullvalenes. More broadly, our computational pipeline should prove useful for rapid characterization of cyclodextrin host-guest complexes, avoiding the need for costly synthesis of guest molecules that are unlikely to bind stably, as well as providing detailed atomic-level insight into the nature of complexation.
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Affiliation(s)
- Zahra Shadfar
- Centre for Theoretical Chemistry and Physics, Institute of Natural and Mathematical Sciences, Massey University, Auckland 0632, New Zealand
| | - Oussama Yahiaoui
- Department of Chemistry, School of Physical Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Thomas A Collier
- Centre for Theoretical Chemistry and Physics, Institute of Natural and Mathematical Sciences, Massey University, Auckland 0632, New Zealand
| | - Thomas Fallon
- Department of Chemistry, School of Physical Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Jane R Allison
- Maurice Wilkins Centre for Molecular Biodiscovery and School of Biological Sciences, University of Auckland, Auckland 1010, New Zealand
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Yahiaoui O, Patel HD, Chinner KS, Pašteka LF, Fallon T. Stereomutation of Substituted Bullvalenes. Org Lett 2021; 23:1157-1162. [PMID: 33146538 DOI: 10.1021/acs.orglett.0c03470] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The stereomutation of substituted bullvalenes is an inevitable consequence of the valence isomerism that automerizes this unique fluxional hydrocarbon. The introduction of external stereogenicity in the substituents expands the reaction graphs and leads to a wealth of complex diastereochemical relationships. In this communication, we explore these possibilities and prepare a range of stereochemically rich substituted bullvalenes. This includes a series of disubstituted bullvalenes with two external stereocenters as a platform for fluxional, shape-diverse compound libraries. We also prepare a tethered bisbullvalene with central stereogenicity in the tether as an ensemble of 900 unique isomers that are completely stereomutable.
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Affiliation(s)
- Oussama Yahiaoui
- Department of Chemistry, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Harshal D Patel
- Department of Chemistry, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Kylie S Chinner
- Department of Chemistry, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Lukáš F Pašteka
- Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences, Comenius University, 81806 Bratislava, Slovakia
| | - Thomas Fallon
- Department of Chemistry, The University of Adelaide, Adelaide, SA 5005, Australia
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