| People | Locations | Statistics |
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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Ferreira, Aimcl
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Topics
Publications (4/4 displayed)
- 2022Ohmic heating-assisted synthesis and characterization of Zn(ii), Cu(ii) and Pd(ii) complexes of heterocyclic-fused chlorinscitations
- 2022Extensive characterization of choline chloride and its solid-liquid equilibrium with watercitations
- 2022Enthalpy of solvation of alkali metal salts in a protic ionic liquid: Effect of cation charge and sizecitations
- 2019Synthesis of Pyridyl and N-Methylpyridinium Analogues of Rosamines: Relevance of Solvent and Charge on Their Photophysical Propertiescitations
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article
Synthesis of Pyridyl and N-Methylpyridinium Analogues of Rosamines: Relevance of Solvent and Charge on Their Photophysical Properties
Abstract
A series of pyridyl analogues of rosamines was prepared by employing two methodologies: (i) the conventional-heating condensation of a pyridinecarboxaldehyde with 3-(diethylamino)phenol in propionic acid, and (ii) the novel ohmic-heating assisted condensation under "on water" conditions, followed by oxidation. The 4-pyridyl substituted rosamine was further converted into the N-methylpyridinium derivative through N-alkylation using methyl iodide. The influence of the position and cationization of the nitrogen atom of the pyridyl ring in the physicochemical properties of fluorophores was investigated by H-1, C-13, N-15 NMR spectral analysis, UV/Vis and fluorescence spectroscopy, single-crystal X-ray diffraction (4-pyridyl and N-methylpyridinium derivatives) and thermal-behavior analysis. Curiously, for ethanolic solutions of 4-pyridyl and N-methylpyridinium derivatives an extinction of color and fluorescence over time was observed. This phenomenon was further studied and the data revealed that it is the result of nucleophilic addition of ethoxide ion to the central 9-position of the xanthene. The kinetics of the process is slower for the 4-pyridyl rosamine, which emphasizes the importance of the charge in the N-methylpyridinium analogue in the reactivity of the molecule towards a nucleophile agent. This phenomenon is reversible, meaning that the compounds can be rapidly recovered by decreasing the pH, opening new avenues in the sensing applications of this class of rosamines.