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Droguett K, Quintero GE, Santos JG, Aliaga ME. Advancement in supramolecular control of organic reactivity induced by cucurbit[n]urils. J INCL PHENOM MACRO 2022. [DOI: 10.1007/s10847-022-01172-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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2
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Photoprocesses in dimers and dimeric complexes of polymethine dyes with cucurbiturils. Russ Chem Bull 2022. [DOI: 10.1007/s11172-022-3398-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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3
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Nie H, Wei Z, Ni XL, Liu Y. Assembly and Applications of Macrocyclic-Confinement-Derived Supramolecular Organic Luminescent Emissions from Cucurbiturils. Chem Rev 2022; 122:9032-9077. [PMID: 35312308 DOI: 10.1021/acs.chemrev.1c01050] [Citation(s) in RCA: 89] [Impact Index Per Article: 44.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Cucurbit[n]urils (Q[n]s or CB[n]s), as a classical of artificial organic macrocyclic hosts, were found to have excellent advantages in the fabricating of tunable and smart organic luminescent materials in aqueous media and the solid state with high emitting efficiency under the rigid pumpkin-shaped structure-derived macrocyclic-confinement effect in recent years. This review aims to give a systematically up-to-date overview of the Q[n]-based supramolecular organic luminescent emissions from the confined spaces triggered host-guest complexes, including the assembly fashions and the mechanisms of the macrocycle-based luminescent complexes, as well as their applications. Finally, challenges and outlook are provided. Since this class of Q[n]-based supramolecular organic luminescent emissions, which have essentially derived from the cavity-dependent confinement effect and the resulting assembly fashions, emerged only a few years ago, we hope this review will provide valuable information for the further development of macrocycle-based light-emitting materials and other related research fields.
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Affiliation(s)
- Haigen Nie
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine (Ministry of Educational of China), Key Laboratory of the Assembly and Application of Organic Functional Molecules of Hunan Province, Hunan Normal University, Changsha, Hunan 410081, China
| | - Zhen Wei
- College of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, China
| | - Xin-Long Ni
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine (Ministry of Educational of China), Key Laboratory of the Assembly and Application of Organic Functional Molecules of Hunan Province, Hunan Normal University, Changsha, Hunan 410081, China.,Key Laboratory of Macrocyclic and Supramolecular Chemistry of Guizhou Province, Guizhou University, Guiyang 550025, China
| | - Yu Liu
- College of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, China
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Thangavel A. Inclusion and Charge Transfer Interaction of a Multi-Redox Active 1,3,5-Triazine Derivative by Cucurbit[7,8]urils. J Org Chem 2021; 86:1178-1182. [PMID: 33327719 DOI: 10.1021/acs.joc.0c02198] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The redox active 1,3,5-triazine derivative (MPT) was used as a guest to study host-guest, charge transfer interaction with CB[7,8] in water. The multi-redox active MPT undergoes four chemically and electrochemically reversible one electron redox states in organic media, but in water, the fourth redox state shows an unstable nature. As a guest, the host-guest interaction of MPT was studied with two macrocyclic cucurbit[7,8]uril (CB[7,8]) hosts in water; resulting supramolecular complexes were characterized by NMR, ESI-MS, UV-vis, ITC, and cyclic voltammetric studies.
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Affiliation(s)
- Arumugam Thangavel
- Department of Chemistry and Biochemistry, California State University Dominguez Hills, Carson, California 90747, United States
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5
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Zakharova GV, Atabekyan LS, Gutrov VN, Chibisov AK. Effect of cucurbit[7]uril on redox photoprocesses of thionine in water. HIGH ENERGY CHEMISTRY 2019. [DOI: 10.1134/s0018143919050151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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6
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Wiemann M, Jonkheijm P. Stimuli-Responsive Cucurbit[n]uril-Mediated Host-Guest Complexes on Surfaces. Isr J Chem 2017. [DOI: 10.1002/ijch.201700109] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Maike Wiemann
- Bioinspired Molecular Engineering Laboratory of the MIRA Institute of Biomedical Technology and Technical Medicine and the Molecular Nanofabrication Group of the MESA Institute for Nanotechnology; University of Twente; P.O. Box 217 7500 AE Enschede The Netherlands
| | - Pascal Jonkheijm
- Bioinspired Molecular Engineering Laboratory of the MIRA Institute of Biomedical Technology and Technical Medicine and the Molecular Nanofabrication Group of the MESA Institute for Nanotechnology; University of Twente; P.O. Box 217 7500 AE Enschede The Netherlands
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Li S, Chan JYW, Li Y, Bardelang D, Zheng J, Yew WW, Chan DPC, Lee SMY, Wang R. Complexation of clofazimine by macrocyclic cucurbit[7]uril reduced its cardiotoxicity without affecting the antimycobacterial efficacy. Org Biomol Chem 2016; 14:7563-9. [PMID: 27439674 DOI: 10.1039/c6ob01060a] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Cucurbit[7]uril (CB[7]) has recently attracted increasing attention in pharmaceutical sciences due to its great potential in improving the physicochemical properties and bioactivity of drug molecules. Herein, we have investigated the influence of CB[7]'s complexation on the solubility, antimycobacterial activity, and cardiotoxicity of a model anti-tuberculosis drug, clofazimine (CFZ), that has poor water-solubility and inherent cardiotoxicity. In our study, CFZ was found to be complexed by CB[7], in a 1 : 1 binding mode with a relatively strong binding affinity (in the order of magnitude of 10(4)-10(5) M(-1)), as determined by the phase solubility method via HPLC-UV analysis and (1)H NMR titration, as well as UV-visible spectroscopic titration, and further confirmed by electrospray ionization mass spectrometry (ESI-MS). Upon complexation, the solubility of virtually insoluble CFZ was significantly increased, reaching a concentration of up to approximately 0.53-fold of the maximum solubility of CB[7]. The inherent cardiotoxicity of CFZ was dramatically reduced to almost nil in the presence of CB[7]. Importantly, on the other hand, such a supramolecular complexation of the drug did not compromise its therapeutic efficacy, as shown by the antimycobacterial activities examined against Mycobacterium smegmatis, demonstrating the significant potential of CB[7] as a functional pharmaceutical excipient.
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Affiliation(s)
- Shengke Li
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Taipa, Macau SAR, China.
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8
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Shewale MN, Lande DN, Gejji SP. Encapsulation of benzimidazole derivatives within cucurbit[7]uril: Density functional investigations. J Mol Liq 2016. [DOI: 10.1016/j.molliq.2015.12.076] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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9
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Barrow SJ, Kasera S, Rowland MJ, del Barrio J, Scherman OA. Cucurbituril-Based Molecular Recognition. Chem Rev 2015; 115:12320-406. [DOI: 10.1021/acs.chemrev.5b00341] [Citation(s) in RCA: 1188] [Impact Index Per Article: 132.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Steven J. Barrow
- Melville
Laboratory for Polymer Synthesis, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Setu Kasera
- Melville
Laboratory for Polymer Synthesis, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Matthew J. Rowland
- Melville
Laboratory for Polymer Synthesis, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Jesús del Barrio
- Melville
Laboratory for Polymer Synthesis, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Oren A. Scherman
- Melville
Laboratory for Polymer Synthesis, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
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MacGillivray BC, Macartney DH. Complexations of the hydrophilic and hydrophobic moieties of benzethonium chloride by cucurbit[7]uril in aqueous solution. CAN J CHEM 2012. [DOI: 10.1139/v2012-078] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The sequential complexations of the hydrophilic and hydrophobic end groups of benzethonium chloride by cucurbit[7]uril (CB[7]) in aqueous solution have been investigated using 1H NMR spectroscopy and electrospray ionization mass spectrometry. The initial binding is to the benzyldimethylammonium group, with a stability constant of (8.7 ± 3.1) × 107 (mol/L)–1. This binding constant and the complexation-induced upfield shifts of the benzyl guest protons are similar to those values observed with other cationic guests containing benzyl moieties. This equilibrium is followed by the binding of a second equivalent of the host to the hydrophobic 2-(2,4,4-trimethylpentyl) group, with a stability constant of (4.0 ± 1.9) × 103 (mol/L)–1. The relatively strong binding of this uncharged hydrophobic end of the guest molecule is consistent with the inclusion of eight heavy (nonhydrogen) atoms within the inner cavity of CB[7], with its low polarizability. The packing coefficient for the 2-(2,4,4-trimethylpentyl) group with the inner cavity is calculated to be 61%, close to Rebek’s ideal value of 55%.
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Affiliation(s)
| | - Donal H. Macartney
- Department of Chemistry, Queen’s University, 90 Bader Lane, Kingston, ON K7L 3N6, Canada
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13
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14
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Peerannawar SR, Gobre VV, Gejji SP. Molecular electrostatic potentials in Cucurbit[n]uril (n=13–16) hosts. COMPUT THEOR CHEM 2011. [DOI: 10.1016/j.comptc.2011.02.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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15
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Macartney DH. Encapsulation of Drug Molecules by Cucurbiturils: Effects on their Chemical Properties in Aqueous Solution. Isr J Chem 2011. [DOI: 10.1002/ijch.201100040] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Kovalenko EA, Mitkina TV, Gerasko OA, Naumov DY, Samsonenko DG, Fedin VP. Inclusion compounds of cucurbit[8]uril with noble metal polyamine complexes. Russ Chem Bull 2011. [DOI: 10.1007/s11172-010-0357-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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17
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Mitkina TV, Naumov DY, Gerasko OA, Fedin VP. Crystal structure and chemical oxidation of the palladium(II) cyclam complex within the cavity of cucurbit[8]uril. Inorganica Chim Acta 2010. [DOI: 10.1016/j.ica.2010.06.031] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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18
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Yang Z, Li Y, Zhou H, Li Q, Gao L. Conductivity and Surface Tension Study for Cucurbit[7]uril Inclusion Complex of Cetyltrimethylammonium Chloride in Aqueous Solution. J DISPER SCI TECHNOL 2010. [DOI: 10.1080/01932690903223567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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19
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Wyman IW, Macartney DH. Host-guest complexes and pseudorotaxanes of cucurbit[7]uril with acetylcholinesterase inhibitors. J Org Chem 2010; 74:8031-8. [PMID: 19799399 DOI: 10.1021/jo901861e] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Pseudorotaxanes may be assembled in aqueous solution using dicationic acetylcholinesterase inhibitors, such as succinylcholine, BW284c51, and alpha,omega-bis(trialkylammonium)alkane dications (or their phosphonium analogues), as bolaform axles and cucurbit[7]uril (CB[7]) as the wheel. With the exceptions of the shorter [(CH(3))(3)N(CH(2))(n)N(CH(3))(3)](2+) (n = 6, 8) dications, the addition of a second CB[7] results in the translocation of the first CB[7], such that the hydrophobic -NR(3)(+) and -PR(3)(+) end groups (R = Me or Et) are located in the cavities of the wheels, while the central portion of the axles extend through the CB[7] portals into the bulk solvent. In the case of the [Quin(CH(2))(10)Quin](2+) (Quin = quinuclidinium) dication, the CB[7] host(s) resides only on the quinuclidinium end group(s). The 1:1 host-guest stability constants range from 8 x 10(6) to 3 x 10(10) M(-1) and are dependent on both the nature of the end group as well as the length and hydrophobicity of the central linker. The magnitude of the stability constants for the 2:1 complexes closely follow the trend observed previously for CB[7] binding with the NR(4)(+) and PR(4)(+) cations.
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Affiliation(s)
- Ian W Wyman
- Department of Chemistry, Queen's University, Kingston, ON K7L 3N6, Canada
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Wyman IW, Macartney DH. Cucurbit[7]urilhost–guest complexes of cholines and phosphonium cholines in aqueous solution. Org Biomol Chem 2010; 8:253-60. [DOI: 10.1039/b917610a] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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21
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Wyman IW, Macartney DH. Host-guest complexations of local anaesthetics by cucurbit[7]uril in aqueous solution. Org Biomol Chem 2009; 8:247-52. [PMID: 20024155 DOI: 10.1039/b915694a] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The cucurbit[7]uril (CB[7]) host molecule forms very stable host-guest complexes with the local anaesthetics procaine (K(CB[7]) = (3.5 +/- 0.7) x 10(4) dm(3) mol(-1)), tetracaine (K(CB[7]) = (1.5 +/- 0.4) x 10(4) dm(3) mol(-1)), procainamide (K(CB[7]) = (7.8 +/- 1.6) x 10(4) dm(3) mol(-1)), dibucaine (K(CB[7]) = (1.8 +/- 0.4) x 10(5) dm(3) mol(-1)) and prilocaine (K(CB[7]) = (2.6 +/- 0.6) x 10(4) dm(3) mol(-1)) in aqueous solution (pD = 4.75). The stability constants are 2-3 orders of magnitude greater than the values reported for binding by the comparably sized beta-cyclodextrin host molecule. The inclusion by CB[7] raises the first pK(a) values of the anaesthetics by 0.5-1.9 pK units, as the protonated forms are bound more strongly in acidic solution. The complexation-induced chemical shift changes in the guest proton resonances provide an indication of the site(s) of binding and the effects of protonation on the location of the binding sites.
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Affiliation(s)
- Ian W Wyman
- Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, Ontario K7L 3N6, Canada
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Hart SL, Haines RI, Decken A, Wagner BD. Isolation of the trans-I and trans-II isomers of CuII(cyclam) via complexation with the macrocyclic host cucurbit[8]uril. Inorganica Chim Acta 2009. [DOI: 10.1016/j.ica.2009.06.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Wang R, MacGillivray BC, Macartney DH. Stabilization of the base-off forms of vitamin B12 and coenzyme B12 by encapsulation of the α-axial 5,6-dimethylbenzimidazole ligand with cucurbit[7]uril. Dalton Trans 2009:3584-9. [DOI: 10.1039/b904028e] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Wyman IW, Macartney DH. Cucurbit[7]uril host-guest and pseudorotaxane complexes with α,ω-bis(pyridinium)alkane dications. Org Biomol Chem 2009; 7:4045-51. [DOI: 10.1039/b910322h] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Houmam A. Electron Transfer Initiated Reactions: Bond Formation and Bond Dissociation. Chem Rev 2008; 108:2180-237. [PMID: 18620366 DOI: 10.1021/cr068070x] [Citation(s) in RCA: 199] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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26
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St-Jacques AD, Wyman IW, Macartney DH. Encapsulation of charge-diffuse peralkylated onium cations in the cavity of cucurbit[7]uril. Chem Commun (Camb) 2008:4936-8. [DOI: 10.1039/b811823j] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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27
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Wang R, Macartney DH. Cucurbit[7]uril stabilization of a diarylmethane carbocation in aqueous solution. Tetrahedron Lett 2008. [DOI: 10.1016/j.tetlet.2007.11.052] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Wyman IW, Macartney DH. Cucurbit[7]uril host–guest complexes with small polar organic guests in aqueous solution. Org Biomol Chem 2008; 6:1796-801. [DOI: 10.1039/b801650j] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Wang R, Macartney DH. Cucurbit[7]uril host–guest complexes of the histamine H2-receptor antagonist ranitidine. Org Biomol Chem 2008; 6:1955-60. [DOI: 10.1039/b801591k] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Wang R, Yuan L, Ihmels H, Macartney DH. Cucurbit[8]uril/Cucurbit[7]uril Controlled Off/On Fluorescence of the Acridizinium and 9-Aminoacridizinium Cations in Aqueous Solution. Chemistry 2007; 13:6468-73. [PMID: 17508370 DOI: 10.1002/chem.200700199] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The blue fluorescence of acridizinium bromide (ADZ+) and the green fluorescence of 9-aminoacridizinium bromide (AADZ+) in aqueous solutions can be almost entirely switched off upon the double inclusion of these guests in the cavity of cucurbit[8]uril (CB[8]) owing to the formation of a nonfluorescent, noncovalent dimer complex, and then fluorescence can be effectively restored by adding cucurbit[7]uril (CB[7]) to the complex because it competitively extracts the fluorophores out of the CB[8] cavity.
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Affiliation(s)
- Ruibing Wang
- Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, ON K7L 3N6, Canada
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Yuan L, Wang R, Macartney DH. Binding Modes of Cucurbit[6]uril and Cucurbit[7]uril with a Tetracationic Bis(viologen) Guest. J Org Chem 2007; 72:4539-42. [PMID: 17503847 DOI: 10.1021/jo070358e] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Binding behaviors of two cucurbit[n]urils (CB[n]) hosts with the [CH3bpy(CH2)6bpyCH3]4+ (bpy = 4,4'-bipyridinium) guest were investigated by 1H NMR and MALDI-TOF-MS experiments. While the CB[6] and CB[7] form [2]pseudorotaxanes with the host located over the hexamethylene chain of the guest, only the CB[7] forms a [3]pseudorotaxane with both host molecules residing over the bipyridinium groups. The initial CB[7] host vacates the inclusion of the hexamethylene chain as a result of the electrostatic and steric repulsions that would arise in simultaneous binding of adjacent aliphatic and aromatic portions of the guest.
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Affiliation(s)
- Lina Yuan
- Department of Chemistry, Queen's University, Kingston, Ontario K7L 3N6, Canada
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Yuan L, Macartney DH. Kinetics of the Electron Self-Exchange and Electron-Transfer Reactions of the (Trimethylammonio)methylferrocene Host−Guest Complex with Cucurbit[7]uril in Aqueous Solution. J Phys Chem B 2007; 111:6949-54. [PMID: 17407346 DOI: 10.1021/jp0701284] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The electron self-exchange rate constants for the (trimethylammonio)methylferrocene(+/2+) couple (FcTMA+/2+) have been measured in the absence and presence of the cucurbit[7]uril (CB[7]) host molecule in aqueous solution, using 1H NMR line-broadening experiments. The very strong binding of the ferrocene to CB[7] results in slow exchange of the guest on the NMR time scale, such that resonances for both the free and bound forms of the reduced ferrocene can be observed. The extents of line broadening in the resonances of the two forms of the guest in the presence of the FcTMA2+ species can be monitored independently, allowing for the determination of the rate constants for the possible self-exchange pathways involving the bound and free forms of both the oxidized and reduced members of the redox couple. The encapsulation of both the reduced and oxidized forms of the ferrocene increases the rate constant (25 degrees C) from (2.1+/-0.1)x10(6) M-1 s-1 (for FcTMA+/2+) to (6.7+/-0.7)x10(6) M(-1) s(-1) (for {FcTMA.CB[7]}+/2+), whereas inclusion of the reduced form only decreases the rate constant to (6+/-1)x10(5) M(-1) s(-1). The changes in the exchange rate constants upon inclusion of the reactants are related to the effects of CB[7] acting as an outer, second-coordination sphere and are compared to those observed previously for the electron-exchange process in the presence of beta-cyclodextrin and p-sulfonated calix[6]arene hosts. The binding of FcTMA+ and hydroxymethylferrocene to CB[7] significantly reduces the rate constants for their oxidations by the bis(2,6-pyridinedicarboxylato)cobaltate(III) ion (which does not bind to CB[7]) as a result of reduced thermodynamic driving forces and steric hindrance to close approach of the oxidant to the encapsulated ferrocenes.
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Affiliation(s)
- Lina Yuan
- Department of Chemistry, Queen's University, Kingston, ON K7L 3N6, Canada
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Yuan L, Wang R, Macartney DH. Chiroptic behaviour of a chiral guest in an achiral cucurbit[7]uril host. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.tetasy.2007.02.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Hettiarachchi DSN, Macartney DH. Cucurbit[7]uril host-guest complexes with cationic bis(4,5-dihydro-1H-imidazol-2-yl) guests in aqueous solution. CAN J CHEM 2006. [DOI: 10.1139/v06-099] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The host–guest interactions between cucurbit[7]uril and a series of novel cationic bis(4,5-dihydro-1H-imidazol-2-yl)arene and 1-(4,5-dihydro-1H-imidazol-2-yl)- and 1,3-bis(4,5-dihydro-1H-imidazol-2-yl)-adamantane guests have been investigated in aqueous solution using UV–vis and NMR spectroscopy, and electrospray mass spectrometry. With the exception of the 1,3-bis(4,5-dihydro-1H-imidazol-2-yl)adamantane (which binds externally to the CB[7]), these guests form very stable inclusion complexes with slow exchange on the 1H NMR timescale. The direction and magnitude of the complexation-induced shifts (CIS) in the proton resonances of the guests are indicative of the residence of the hydrophobic core of the guest within the CB[7] cavity and the charged 4,5-dihydro-1H-imidazol-2-yl units outside the cavity adjacent to the carbonyl-lined portals of the host. The CIS values and the inclusion stability constants have been correlated with the nature of the guest core and with the distance between the charges on the terminal 4,5-dihydro-1H-imidazol-2-yl rings.Key words: cucurbit[7]uril, host–guest complex, dihydroimidazolyl, inclusion stability constants.
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Wang R, Yuan L, Macartney DH. Inhibition of C(2)-H/D exchange of a bis(imidazolium) dication upon complexation with cucubit[7]uril. Chem Commun (Camb) 2006:2908-10. [PMID: 17007413 DOI: 10.1039/b605919h] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Inclusion of the alpha,alpha'-bis(3-(1-methylimidazolium))-p-xylene dication in cucurbit[7]uril (CB[7], K(CB[7]) = (4.3 x 10(9) M(-1)), with C-H...O=C hydrogen bonding between the guest C(2)-protons and the carbonyl oxygens of the host portals, inhibits the H/D exchange for the C(2)-proton with k(OD) (25 degrees C, D2O) decreasing from 1.2 x 10(3) M(-1) s(-1) (pKa = 22.3) in the absence of CB[7] to 0.9 M(-1) s(-1) (pKa = 25.4) in the presence of 1.1 equiv. CB[7].
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Affiliation(s)
- Ruibing Wang
- Department of Chemistry, Queen's University, Kingston, ON, Canada K7L 3N6
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