Spectral changes and reactivity of azacumarine homologes in supramolecular systems based on cyclodextrins and cucurbiturils
Cyclodextrins (CDs) and cucurbiturils (CBs) are host molecules, relatively soluble in water with cavities described as hydrophobic. Although the cavity polarity of CDs and CBs is similar, their structural and dimensional differences have produced variations in their functionality in terms of reactiv...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2021 |
| País: | Chile |
| OAI Identifier: | oai:repositorio.anid.cl:10533/42665 |
| Acceso en línea: | https://hdl.handle.net/10533/42665 |
| Access Level: | acceso abierto |
| Palabra clave: | Ciencias Naturales Ciencias Químicas Otras Especialidades de la Química |
| Sumario: | Cyclodextrins (CDs) and cucurbiturils (CBs) are host molecules, relatively soluble in water with cavities described as hydrophobic. Although the cavity polarity of CDs and CBs is similar, their structural and dimensional differences have produced variations in their functionality in terms of reactivity and selectivity. In this context, this research work has as a general objective, to evaluate the spectral behaviors and the reactivity against the hydrolysis reaction for a series of substituted aza-coumarins in the presence and absence of CDs and CBs. For this, five homologues of 3-substituted 7-(dialkylamino)aza-coumarin (DAAS) were successfully synthesized and characterized by NMR, ESI-HRMS and IR. Then such substrates were studied spectroscopically in aqueous solution in the absence and presence of β-CD, DM-β-CD, γ-CD and CB7. The results showed that the spectral properties of the synthesized DAAS and their reactivities against the hydrolysis reaction can be affected depending on the nature of the macrocycle used, with CB7 and DM-β-CD being the most influential macrocycles in the kinetic results of DAAS. this work. Among the results, the following stand out: large bathochromic effects (4500cm-1) and total deactivation of the DAAS emission, attributed to the protonation of the heterocyclic nitrogen of the substrate after its inclusion in CB7. It also highlights an increase of up to 5.5 times in the quantum yield of DAAS in the presence of DM-β-CD. In terms of reactivity, DM-β-CD and CB7 produced significant inhibition effects against the hydrolysis reaction in acid medium for DAAS of the Schiff base type (DMSB), with different association constants 3x103 and 2x105 M-1, respectively. Finally, to elucidate the inhibition effect, a kinetic study on imino-coumarins (IC) was carried out, in such a way that a general kinetic model for the acid hydrolysis of imines, in the presence of CB7, was proposed. |
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