Conversion of Isocyanide to Amine in The Presence of Water and Hg(II) Ions: Kinetics and Mechanism as Detected by Fluorescence Spectroscopy and Mass Spectrometry
Aromatic isocyanides including isocyanonaphthalene derivatives have been proven to be very effective fluorescent sensors for the quantification of Hg(II) ions in water. Thus, the reaction of 1,5-isocyanoaminonaphthalene (1,5-ICAN), which is one of the most important members of this family, with wate...
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MDPI AG
2020-08-01
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| Series: | International Journal of Molecular Sciences |
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| Online Access: | https://www.mdpi.com/1422-0067/21/15/5588 |
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| author | Anita Adamoczky Lajos Nagy Miklós Nagy Miklós Zsuga Sándor Kéki |
| author_facet | Anita Adamoczky Lajos Nagy Miklós Nagy Miklós Zsuga Sándor Kéki |
| author_sort | Anita Adamoczky |
| collection | DOAJ |
| description | Aromatic isocyanides including isocyanonaphthalene derivatives have been proven to be very effective fluorescent sensors for the quantification of Hg(II) ions in water. Thus, the reaction of 1,5-isocyanoaminonaphthalene (1,5-ICAN), which is one of the most important members of this family, with water and HgCl<sub>2</sub> as the oxidation agents, was studied by fluorescence spectroscopy and mass spectrometry in order to get deeper insight into the kinetics and mechanistic details of this complex reaction. The reactions of 1,5-ICAN with water and HgCl<sub>2</sub> were performed in various water/co-solvent mixtures of different compositions. The co-solvents used in this study were both aprotic solvents including tetrahydrofuran, acetonitrile and N,N-dimethylformamide and protic solvents, such as ethanol and 2-propanol. It was found that in aprotic solvents the conversion of the isocyano group to amino moiety takes place, while in protic solvents the corresponding carbamate (urethane) group is formed in addition to the amino moiety. The variation of the resulting fluorescence intensities versus time curves were described using an irreversible, consecutive reaction model, in which the formation of isocyanate and carbamic acid intermediates, as well as diamino and carbamate (in the case of protic solvents) products were assumed. The formation of these intermediates and products was unambiguously confirmed by mass spectrometric measurements. Furthermore, by fitting the model to the experimental fluorescence versus time curves, the corresponding rate coefficients were determined. It was observed that the overall rate of transformation of the isocyano group to amino moiety increased with the water concentration and the polarity of the co-solvent. It was also supported that formation of diamino and carbamate derivatives in protic solvents takes place simultaneously and that the ratio of the amino to the carbamate function increased with the increasing water concentration. In addition, with an extension, the model presented herein proved to be capable of describing the kinetics of the transformation of 1,5-diisocyanonaphthalene (1,5-DIN) into 1,5-diaminonaphthalene (1,5-DAN) in the mixtures of water/aprotic solvents. |
| first_indexed | 2024-03-10T17:58:37Z |
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| issn | 1661-6596 1422-0067 |
| language | English |
| last_indexed | 2024-03-10T17:58:37Z |
| publishDate | 2020-08-01 |
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| series | International Journal of Molecular Sciences |
| spelling | doaj.art-f72d96d6a64c40b69124ed6866f49ce12023-11-20T09:05:34ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672020-08-012115558810.3390/ijms21155588Conversion of Isocyanide to Amine in The Presence of Water and Hg(II) Ions: Kinetics and Mechanism as Detected by Fluorescence Spectroscopy and Mass SpectrometryAnita Adamoczky0Lajos Nagy1Miklós Nagy2Miklós Zsuga3Sándor Kéki4Department of Applied Chemistry, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, HungaryDepartment of Applied Chemistry, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, HungaryDepartment of Applied Chemistry, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, HungaryDepartment of Applied Chemistry, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, HungaryDepartment of Applied Chemistry, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, HungaryAromatic isocyanides including isocyanonaphthalene derivatives have been proven to be very effective fluorescent sensors for the quantification of Hg(II) ions in water. Thus, the reaction of 1,5-isocyanoaminonaphthalene (1,5-ICAN), which is one of the most important members of this family, with water and HgCl<sub>2</sub> as the oxidation agents, was studied by fluorescence spectroscopy and mass spectrometry in order to get deeper insight into the kinetics and mechanistic details of this complex reaction. The reactions of 1,5-ICAN with water and HgCl<sub>2</sub> were performed in various water/co-solvent mixtures of different compositions. The co-solvents used in this study were both aprotic solvents including tetrahydrofuran, acetonitrile and N,N-dimethylformamide and protic solvents, such as ethanol and 2-propanol. It was found that in aprotic solvents the conversion of the isocyano group to amino moiety takes place, while in protic solvents the corresponding carbamate (urethane) group is formed in addition to the amino moiety. The variation of the resulting fluorescence intensities versus time curves were described using an irreversible, consecutive reaction model, in which the formation of isocyanate and carbamic acid intermediates, as well as diamino and carbamate (in the case of protic solvents) products were assumed. The formation of these intermediates and products was unambiguously confirmed by mass spectrometric measurements. Furthermore, by fitting the model to the experimental fluorescence versus time curves, the corresponding rate coefficients were determined. It was observed that the overall rate of transformation of the isocyano group to amino moiety increased with the water concentration and the polarity of the co-solvent. It was also supported that formation of diamino and carbamate derivatives in protic solvents takes place simultaneously and that the ratio of the amino to the carbamate function increased with the increasing water concentration. In addition, with an extension, the model presented herein proved to be capable of describing the kinetics of the transformation of 1,5-diisocyanonaphthalene (1,5-DIN) into 1,5-diaminonaphthalene (1,5-DAN) in the mixtures of water/aprotic solvents.https://www.mdpi.com/1422-0067/21/15/5588steady-state fluorescencekineticsisocyanoaminonaphthalenesHgCl<sub>2</sub>carbamic acidcarbamate |
| spellingShingle | Anita Adamoczky Lajos Nagy Miklós Nagy Miklós Zsuga Sándor Kéki Conversion of Isocyanide to Amine in The Presence of Water and Hg(II) Ions: Kinetics and Mechanism as Detected by Fluorescence Spectroscopy and Mass Spectrometry International Journal of Molecular Sciences steady-state fluorescence kinetics isocyanoaminonaphthalenes HgCl<sub>2</sub> carbamic acid carbamate |
| title | Conversion of Isocyanide to Amine in The Presence of Water and Hg(II) Ions: Kinetics and Mechanism as Detected by Fluorescence Spectroscopy and Mass Spectrometry |
| title_full | Conversion of Isocyanide to Amine in The Presence of Water and Hg(II) Ions: Kinetics and Mechanism as Detected by Fluorescence Spectroscopy and Mass Spectrometry |
| title_fullStr | Conversion of Isocyanide to Amine in The Presence of Water and Hg(II) Ions: Kinetics and Mechanism as Detected by Fluorescence Spectroscopy and Mass Spectrometry |
| title_full_unstemmed | Conversion of Isocyanide to Amine in The Presence of Water and Hg(II) Ions: Kinetics and Mechanism as Detected by Fluorescence Spectroscopy and Mass Spectrometry |
| title_short | Conversion of Isocyanide to Amine in The Presence of Water and Hg(II) Ions: Kinetics and Mechanism as Detected by Fluorescence Spectroscopy and Mass Spectrometry |
| title_sort | conversion of isocyanide to amine in the presence of water and hg ii ions kinetics and mechanism as detected by fluorescence spectroscopy and mass spectrometry |
| topic | steady-state fluorescence kinetics isocyanoaminonaphthalenes HgCl<sub>2</sub> carbamic acid carbamate |
| url | https://www.mdpi.com/1422-0067/21/15/5588 |
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