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Matthews SE, Cecioni S, O'Brien JE, MacDonald CJ, Hughes DL, Jones GA, Ashworth SH, Vidal S. Fixing the Conformation of Calix[4]arenes: When Are Three Carbons Not Enough? Chemistry 2018; 24:4436-4444. [PMID: 29338100 DOI: 10.1002/chem.201705955] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Indexed: 01/17/2023]
Abstract
Calix[4]arenes are unique macrocycles that through judicious functionalisation at the lower rim can be either fixed in one of four conformations or remain conformationally flexible. Introduction of propynyl or propenyl groups unexpectedly provides a new possibility; a unidirectional conformational switch, with the 1,3-alternate and 1,2-alternate conformers switching to the partial cone conformation, whilst the cone conformation is unchanged, under standard experimental conditions. Using 1 H NMR kinetic studies, rates of switching have been shown to be dependent on the starting conformation, upper-rim substituent, where reduction in bulk enables faster switching, solvent and temperature with 1,2-alternate conformations switching fastest. Ab initio calculations (DFT) confirmed the relative stabilities of the conformations and point towards the partial cone conformer being the most stable of the four. The potential impact on synthesis through the "click" reaction has been investigated and found not to be significant.
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Affiliation(s)
- Susan E Matthews
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Samy Cecioni
- Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, CO2-Glyco, UMR 5246, CNRS, Université Claude Bernard Lyon 1, 43 Boulevard du 11 Novembre 1918, 69622, Villeurbanne, France
| | - John E O'Brien
- School of Chemistry, University of Dublin, Trinity College, Dublin 2, Ireland
| | - Colin J MacDonald
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - David L Hughes
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Garth A Jones
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Stephen H Ashworth
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Sébastien Vidal
- Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, CO2-Glyco, UMR 5246, CNRS, Université Claude Bernard Lyon 1, 43 Boulevard du 11 Novembre 1918, 69622, Villeurbanne, France
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Talotta C, Gaeta C, De Rosa M, Ascenso JR, Marcos PM, Neri P. Alkylammonium Guest Induced-Fit Recognition by a Flexible Dihomooxacalix[4]arene Derivative. European J Org Chem 2015. [DOI: 10.1002/ejoc.201501319] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Bolliger JL, Ronson TK, Ogawa M, Nitschke JR. Solvent effects upon guest binding and dynamics of a Fe(II)4L4 cage. J Am Chem Soc 2014; 136:14545-53. [PMID: 25226369 DOI: 10.1021/ja5077102] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Solvent-dependent host-guest chemistry and favoring of otherwise disfavored conformations of large guests has been achieved with an adaptive, self-assembled Fe(II)4L4 coordination cage. Depending on the counterion, this face-capped tetrahedral capsule is soluble either in water or in acetonitrile and shows a solvent-dependent preference for encapsulation of certain classes of guest molecules. Quantitative binding studies were undertaken, revealing that both aromatic and aliphatic guests bind in water, whereas only aliphatic guests bind in acetonitrile. The flexibility of its subcomponent building blocks allows this cage to expand or contract upon guest binding, as studied by VT-NMR, thereby ensuring strong binding of both small and large guests. Upon encapsulation, large guest molecules can adopt conformations which are not thermodynamically favored in the free state. In addition, the chirotopic inner phase of the cage renders enantiotopic guest proton signals diastereotopic in specific cases.
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Affiliation(s)
- Jeanne L Bolliger
- Department of Chemistry, University of Cambridge , Lensfield Road, Cambridge CB2 1EW, United Kingdom
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Cervantes R, Sánchez RI, Tiburcio J. Co-Conformational Isomerism in a Neutral Ion-Paired Supramolecular System. Chemistry 2013; 19:4051-7. [DOI: 10.1002/chem.201203483] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2012] [Indexed: 11/10/2022]
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Gaeta C, Troisi F, Talotta C, Pierro T, Neri P. Introduction of Glyco, Peptido, Carboxy, and Alkyno Substituents at the Calixarene Exo Rim via the p-Bromodienone Route. J Org Chem 2012; 77:3634-9. [DOI: 10.1021/jo300107g] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Carmine Gaeta
- Dipartimento di Chimica e Biologia, Università di Salerno, Via Ponte don Melillo, I-84084 Fisciano,
Salerno, Italy
| | - Francesco Troisi
- Dipartimento di Chimica e Biologia, Università di Salerno, Via Ponte don Melillo, I-84084 Fisciano,
Salerno, Italy
| | - Carmen Talotta
- Dipartimento di Chimica e Biologia, Università di Salerno, Via Ponte don Melillo, I-84084 Fisciano,
Salerno, Italy
| | - Teresa Pierro
- Dipartimento di Chimica e Biologia, Università di Salerno, Via Ponte don Melillo, I-84084 Fisciano,
Salerno, Italy
| | - Placido Neri
- Dipartimento di Chimica e Biologia, Università di Salerno, Via Ponte don Melillo, I-84084 Fisciano,
Salerno, Italy
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Gaeta C, Talotta C, Farina F, Campi G, Camalli M, Neri P. Conformational Features and Recognition Properties of a Conformationally Blocked Calix[7]arene Derivative. Chemistry 2011; 18:1219-30. [DOI: 10.1002/chem.201102179] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Indexed: 11/09/2022]
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