Evaluation of the supramolecular interaction of Congo red with cucurbiturils using mass spectrometry and spectroscopic methods
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Publication Date: | 2020 |
Other Authors: | , , , , , |
Format: | Article |
Language: | eng |
Source: | Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
Download full: | http://hdl.handle.net/10773/27979 |
Summary: | The ability of cucurbit[n]urils (CB[n]) to decolourise aqueous solutions of the azo dye Congo red (CR) was described more than a century ago alongside the first synthesis of CB[n]. No subsequent studies of the nature of the physical interactions have been reported despite the interest in using CB[n] as adsorbents for the removal of CR and related organic dyes from wastewaters. In the present work the supramolecular interaction between CB[n] (n = 7, 8) and CR was studied by electrospray ionisation mass spectrometry (ESI-MS), 1H NMR, and solid-state characterisation of isolated complexes. Under positive ESI, the formation of host–guest complexes in the gas phase was not observed, suggesting that CR anions do not interact with the portals and the nonpolar inner cavity of the CB[n] molecules. Conversely, under negative ESI, 1 : 1 and higher order (1 : 2, 2 : 1, 3 : 1 and 2 : 2) CR: CB[7] and CR: CB[8] adducts were detected, which is attributed to interaction between CR and the outer surface hydrogens of CB[n]. Solid-state supramolecular adducts between CB[n] and CR were isolated from aqueous media under either ambient conditions, giving structures denoted as CR@CB[n](RT), or hydrothermal (100 ºC) conditions, giving structures denoted as CR@CB[n](100). The adducts were characterised by elemental and thermogravimetric analyses (TGA), powder X-ray diffraction (PXRD), and spectroscopic methods (FT-IR, FT-Raman, 13C{1H} CP MAS NMR, UV/vis and near-IR absorption, fluorescence excitation and emission). The interaction conditions and acid content of the starting CB[n] influenced the protonation state of CR molecules. CR@CB[7](RT) contained only unprotonated CR, while CR@CB[8](100) contained exclusively protonated CR (ammonium and azonium/quinoid structures). Other adducts contained mixtures of protonated/unprotonated forms. |
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Evaluation of the supramolecular interaction of Congo red with cucurbiturils using mass spectrometry and spectroscopic methodsThe ability of cucurbit[n]urils (CB[n]) to decolourise aqueous solutions of the azo dye Congo red (CR) was described more than a century ago alongside the first synthesis of CB[n]. No subsequent studies of the nature of the physical interactions have been reported despite the interest in using CB[n] as adsorbents for the removal of CR and related organic dyes from wastewaters. In the present work the supramolecular interaction between CB[n] (n = 7, 8) and CR was studied by electrospray ionisation mass spectrometry (ESI-MS), 1H NMR, and solid-state characterisation of isolated complexes. Under positive ESI, the formation of host–guest complexes in the gas phase was not observed, suggesting that CR anions do not interact with the portals and the nonpolar inner cavity of the CB[n] molecules. Conversely, under negative ESI, 1 : 1 and higher order (1 : 2, 2 : 1, 3 : 1 and 2 : 2) CR: CB[7] and CR: CB[8] adducts were detected, which is attributed to interaction between CR and the outer surface hydrogens of CB[n]. Solid-state supramolecular adducts between CB[n] and CR were isolated from aqueous media under either ambient conditions, giving structures denoted as CR@CB[n](RT), or hydrothermal (100 ºC) conditions, giving structures denoted as CR@CB[n](100). The adducts were characterised by elemental and thermogravimetric analyses (TGA), powder X-ray diffraction (PXRD), and spectroscopic methods (FT-IR, FT-Raman, 13C{1H} CP MAS NMR, UV/vis and near-IR absorption, fluorescence excitation and emission). The interaction conditions and acid content of the starting CB[n] influenced the protonation state of CR molecules. CR@CB[7](RT) contained only unprotonated CR, while CR@CB[8](100) contained exclusively protonated CR (ammonium and azonium/quinoid structures). Other adducts contained mixtures of protonated/unprotonated forms.Royal Society of Chemistry2021-02-14T00:00:00Z2020-01-20T00:00:00Z2020-01-20info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfhttp://hdl.handle.net/10773/27979eng1144–054610.1039/C9NJ05706DCosta, Ana L.Gomes, Ana C.Lopes, André D.Da Silva, José P.Pillinger, MartynGonçalves, Isabel S.Seixas de Melo, J. Sérgioinfo:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2024-02-22T11:54:01Zoai:ria.ua.pt:10773/27979Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-20T03:00:34.862880Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse |
dc.title.none.fl_str_mv |
Evaluation of the supramolecular interaction of Congo red with cucurbiturils using mass spectrometry and spectroscopic methods |
title |
Evaluation of the supramolecular interaction of Congo red with cucurbiturils using mass spectrometry and spectroscopic methods |
spellingShingle |
Evaluation of the supramolecular interaction of Congo red with cucurbiturils using mass spectrometry and spectroscopic methods Costa, Ana L. |
title_short |
Evaluation of the supramolecular interaction of Congo red with cucurbiturils using mass spectrometry and spectroscopic methods |
title_full |
Evaluation of the supramolecular interaction of Congo red with cucurbiturils using mass spectrometry and spectroscopic methods |
title_fullStr |
Evaluation of the supramolecular interaction of Congo red with cucurbiturils using mass spectrometry and spectroscopic methods |
title_full_unstemmed |
Evaluation of the supramolecular interaction of Congo red with cucurbiturils using mass spectrometry and spectroscopic methods |
title_sort |
Evaluation of the supramolecular interaction of Congo red with cucurbiturils using mass spectrometry and spectroscopic methods |
author |
Costa, Ana L. |
author_facet |
Costa, Ana L. Gomes, Ana C. Lopes, André D. Da Silva, José P. Pillinger, Martyn Gonçalves, Isabel S. Seixas de Melo, J. Sérgio |
author_role |
author |
author2 |
Gomes, Ana C. Lopes, André D. Da Silva, José P. Pillinger, Martyn Gonçalves, Isabel S. Seixas de Melo, J. Sérgio |
author2_role |
author author author author author author |
dc.contributor.author.fl_str_mv |
Costa, Ana L. Gomes, Ana C. Lopes, André D. Da Silva, José P. Pillinger, Martyn Gonçalves, Isabel S. Seixas de Melo, J. Sérgio |
description |
The ability of cucurbit[n]urils (CB[n]) to decolourise aqueous solutions of the azo dye Congo red (CR) was described more than a century ago alongside the first synthesis of CB[n]. No subsequent studies of the nature of the physical interactions have been reported despite the interest in using CB[n] as adsorbents for the removal of CR and related organic dyes from wastewaters. In the present work the supramolecular interaction between CB[n] (n = 7, 8) and CR was studied by electrospray ionisation mass spectrometry (ESI-MS), 1H NMR, and solid-state characterisation of isolated complexes. Under positive ESI, the formation of host–guest complexes in the gas phase was not observed, suggesting that CR anions do not interact with the portals and the nonpolar inner cavity of the CB[n] molecules. Conversely, under negative ESI, 1 : 1 and higher order (1 : 2, 2 : 1, 3 : 1 and 2 : 2) CR: CB[7] and CR: CB[8] adducts were detected, which is attributed to interaction between CR and the outer surface hydrogens of CB[n]. Solid-state supramolecular adducts between CB[n] and CR were isolated from aqueous media under either ambient conditions, giving structures denoted as CR@CB[n](RT), or hydrothermal (100 ºC) conditions, giving structures denoted as CR@CB[n](100). The adducts were characterised by elemental and thermogravimetric analyses (TGA), powder X-ray diffraction (PXRD), and spectroscopic methods (FT-IR, FT-Raman, 13C{1H} CP MAS NMR, UV/vis and near-IR absorption, fluorescence excitation and emission). The interaction conditions and acid content of the starting CB[n] influenced the protonation state of CR molecules. CR@CB[7](RT) contained only unprotonated CR, while CR@CB[8](100) contained exclusively protonated CR (ammonium and azonium/quinoid structures). Other adducts contained mixtures of protonated/unprotonated forms. |
publishDate |
2020 |
dc.date.none.fl_str_mv |
2020-01-20T00:00:00Z 2020-01-20 2021-02-14T00:00:00Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://hdl.handle.net/10773/27979 |
url |
http://hdl.handle.net/10773/27979 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
1144–0546 10.1039/C9NJ05706D |
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info:eu-repo/semantics/openAccess |
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openAccess |
dc.format.none.fl_str_mv |
application/pdf |
dc.publisher.none.fl_str_mv |
Royal Society of Chemistry |
publisher.none.fl_str_mv |
Royal Society of Chemistry |
dc.source.none.fl_str_mv |
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Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
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RCAAP |
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RCAAP |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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