Excited state chemistry of flavone derivatives in a confined medium: ESIPT emission in aqueous media

Santos, Fabiano S.; Ramasamy, Elamparuthi; Ramamurthy, V.; Rodembusch, Fabiano Severo

doi:10.1039/c4pp00096j

Cited by 46 publications

(31 citation statements)

References 52 publications

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“…Based on this result, the emission at shorter wavelengths, so-called normal emission (N*), can be attributed to a radiative deactivation of a locally excited conformer, structurally not able to proton transfer. 23 On the other hand, the emission at longer wavelengths can be ascribed to the ESIPT process, which arises from an enol-cis conformer that can present proton transfer in the excited state. 23 In this process, an excited enol-cis conformer (N*) arises, and tautomerizes to an excited-state keto (T*) species (as presented in Figure 1).…”

Section: Photophysical Characterizationmentioning

confidence: 99%

“…23 On the other hand, the emission at longer wavelengths can be ascribed to the ESIPT process, which arises from an enol-cis conformer that can present proton transfer in the excited state. 23 In this process, an excited enol-cis conformer (N*) arises, and tautomerizes to an excited-state keto (T*) species (as presented in Figure 1). The latter decays to the ground state (T) emitting fluorescence (T* emission) with a large Stokes' shift.…”

Section: Photophysical Characterizationmentioning

confidence: 99%

“…The notation N* and T* are the normal and tautomeric emissions, respectively fluorescence emission tailored by the environment. 23 As the synthesized compounds 8-9 present a fluorophoric unit able to proton transfer in the excited state, it was decided to investigate their fluorescence emission in the presence of different amounts of fluoride ion ( Figure 5). …”

Section: Complexation Studymentioning

confidence: 99%

“…The ESIPT process can generally be found in benzazoles, flavonols and chromones and can be understood as a four-level photochemical cycle that produces a tautomer with a different electronic structure from the ground state enol conformer ( Figure 1). 23 Numerous applications can be found in chemistry, biology and biochemistry based on these ESIPT features. [24][25][26][27][28][29][30] The ESIPT process is characterized by a dual fluorescence emission tailored by the solvent polarity, 31 with the emission from the tautomeric form (T*) showing a large Stokes' shift (even in the solid state) compared to normal forms (N*).…”

mentioning

confidence: 99%

“…However, depending on the chemical structure of the fluorophore, the ESIPT mechanism can be strongly dependent on the solvent, as different conformers can be stabilized in solution in the ground state, that do not proton transfer in the excited state and decay emitting at lower wavelengths (N* emission). 23 Thus, we present here the synthesis and photophysical characterization of two new compounds containing a fluorophoric unit, allowing proton transfer in the excited state (ESIPT) to explore phototautomerism as an additional tool for recognizing anions in solution.…”

mentioning

confidence: 99%

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Synthesis and Photophysical Characterization of Proton Transfer-Based Thiourea Derivatives: Potential Application as Colorimetric Naked-Eye Chemosensor for Fluoride Detection in Solution

Silva¹,

Kroetz²,

Santos³

et al. 2017

J. Braz. Chem. Soc.

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Two new thiourea derivatives were synthesized through the reaction of photoactive aminohydroxybenzazoles and p-isothiocyanate benzoic acid via nucleophilic addition reaction. The compounds were characterized using high resolution mass spectrometry with eletrospray ionization (HRMS-ESI), Fourier transform infrared (FTIR), 13C and 1 H nuclear magnetic resonance (NMR) spectroscopies. UV-Vis and steady-state fluorescence in solution were also applied to characterize their photophysical behavior. The compounds present absorption in the ultraviolet region (ca. 300 nm) and fluorescence emission with a large Stokes' shift in the UV-A and green region, with the longer wavelength related to phototautomerism in the excited state (ESIPT). Both compounds were investigated as optical sensors for the detection of anions in solution, presenting a potential application for fluoride ion detection by naked-eye and UV-Vis spectroscopy. The continuous variation method plot gave a 1:1 stoichiometric ratio between the chemosensors and F -for the new formed species. The UV-Vis and 1 H NMR titration experiments reflect the establishment of a hydrogen bond interaction between the thiourea moiety of the chemosensors and fluoride. In addition, the presence of fluoride in solution tailored the fluorescence emission of one compound favoring the ESIPT emission.

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Section: Photophysical Characterizationmentioning

confidence: 99%

Section: Photophysical Characterizationmentioning

confidence: 99%

Section: Complexation Studymentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Synthesis and Photophysical Characterization of Proton Transfer-Based Thiourea Derivatives: Potential Application as Colorimetric Naked-Eye Chemosensor for Fluoride Detection in Solution

Silva¹,

Kroetz²,

Santos³

et al. 2017

J. Braz. Chem. Soc.

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A Picosecond Time‐Resolved Spectroscopic Investigation of the Effect of pH on Morin Fluorescence

et al. 2020

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In this work, we investigated for the first time morin in MeOH at different pH values by picosecond time‐resolved fluorescence. We identified the two species responsible for the fluorescence at low and high pH. The solvated morin‐solvent hydrogen‐bonded complex has been experimentally observed for the first time. We give also the typical fluorescence spectra as well as the fluorescence lifetimes of the probable emitting species. In this work we put forward new insights concerning the contribution of free morin to the fluorescence. We hope that these new data improve the accuracy of the interpretation of the cation:morin complexes titration using fluorescence signal.

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Confinement as a Tool in Chemistry: Accelerated Intracapsular Dimerization of Cyclopentadiene in Water

Sam Sunny,

Ramamurthy

2024

Israel Journal of Chemistry

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In this study, the occurrence of Diels–Alder reaction of cyclopentadiene yielding dicyclopentadiene within a confined closed space provided by octa acid (OA) in water at room temperature is established. The Diels–Alder reaction within the OA capsule occurs at least 2000 times faster than in water. Catalysis of Diels–Alder reaction by hosts such as cyclodextrin, cucurbituril, and Fujita's Pd nano–host occurs in water. Despite their similarity, these three hosts provide an open environment where the reactant molecules are exposed to aqueous environment. The only fully closed host known to catalyze the Diels–Alder reaction in water is OA. Although Rebek's host is established to catalyze Diels–Alder reaction it occurs in an organic solvent. The closed environment explored in this presentation provides an opportunity to better understand the origin of non–covalent catalysis in a restricted space and in water. Because the product binds stronger than the reactant, disappointingly, the capsule can't be recycled. We recognize that this aspect needs to be addressed for the OA capsule to become synthetically useful. We are in the process of understanding the origin of catalysis and finding ways to make reaction recyclable.

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Excited state chemistry of flavone derivatives in a confined medium: ESIPT emission in aqueous media

Cited by 46 publications

References 52 publications

Synthesis and Photophysical Characterization of Proton Transfer-Based Thiourea Derivatives: Potential Application as Colorimetric Naked-Eye Chemosensor for Fluoride Detection in Solution

Synthesis and Photophysical Characterization of Proton Transfer-Based Thiourea Derivatives: Potential Application as Colorimetric Naked-Eye Chemosensor for Fluoride Detection in Solution

A Picosecond Time‐Resolved Spectroscopic Investigation of the Effect of pH on Morin Fluorescence

Confinement as a Tool in Chemistry: Accelerated Intracapsular Dimerization of Cyclopentadiene in Water

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