Determination of ground and excited state dipole moments of amino-benzimidazole by solvatochromic shift methods and theoretical calculations

Thiaré, Diène Diégane; Khonté, Abdourahmane; Diop, A.; Cissé, Lamine; Coly, Atanasse; Tine, Alphonse; Delattre, François

doi:10.1016/j.molliq.2015.07.071

Cited by 20 publications

(8 citation statements)

References 22 publications

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“…The dipole moment of a molecule in the excited state can be determined using the solvatochromic method [ 55 , 56 , 57 , 58 ], which is dependent on the internal electric field effect. There are linear correlations between the location of absorbance and fluorescence maxima, with the solvent polarity parameters including the dielectric constant (e) and refractive effect (n) of the solvent.…”

Section: Methodsmentioning

confidence: 99%

ESIPT-Related Origin of Dual Fluorescence in the Selected Model 1,3,4-Thiadiazole Derivatives

et al. 2020

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In our previous work, we discussed the emergence of the dual fluorescence phenomenon in selected compounds from the group of 1,3,4-thiadiazoles. The results obtained in a number of experimental studies, supported by [TD]DFT calculations, clearly indicated that the phenomenon of dual fluorescence stemmed from an overlap of several factors, including the correct conformation of the analyzed molecule and, very significantly in this context, aggregation effects. Where those two conditions were met, we could observe the phenomenon of intermolecular charge transfer (CT) and the emergence of electronic states responsible for long wave emissions. However, in light of the new studies presented in this paper, we were able, for the first time, to provide a specific theory for the effect of dual fluorescence observed in the analyzed group of 1,3,4-thiadiazoles. We present the results of spectroscopic measurements conducted for two selected analogues from the 1,3,4-thiadiazole group, both in polar and non-polar solvents, which clearly evidence (as we have already suspected in the past, albeit have not shown in publications to date) the possibility of processes related to emission from the tautomer formed in the process of excited state intramolecular proton transfer, which is responsible for the long-wavelength emissions observed in the selected analogues. The presented results obtained with the use of UV-Vis, fluorescence (stationary and time-resolved), FTIR, and Raman spectroscopy, as well as from calculations of dipole moment changes between the ground and excited state with the use of two derivatives with different structures of the resorcylic system, corroborated our standing hypothesis. At the same time, they excluded the presence of ground state keto forms of the analyzed analogues unless necessitated by the structure of the molecule itself. In this case, aggregation factors enhance the observed effects related to the dual fluorescence of the analyzed compounds (by way of AIE—aggregated induced emissions).

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Section: Methodsmentioning

confidence: 99%

ESIPT-Related Origin of Dual Fluorescence in the Selected Model 1,3,4-Thiadiazole Derivatives

et al. 2020

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“…La valeur normalisée de l'intensité de fluorescence augmente d'une manière significative avec la polarité et la polarisabilité des solvants excepté le DMSO (Tableau 1). L'effet du solvant a montré que le naphtopyranone présente un important signal de fluorescence dans le méthanol qui pourrait s'expliquer par des interactions de moyenne intensité avec le soluté (Thiaré et al, 2015b). La faible intensité de fluorescence observée dans le diméthylsulfoxyde peut s'expliquer par de fortes interactions solvantsoluté (Thiaré et al, 2015b).…”

Section: Discussionunclassified

“…L'effet du solvant a montré que le naphtopyranone présente un important signal de fluorescence dans le méthanol qui pourrait s'expliquer par des interactions de moyenne intensité avec le soluté (Thiaré et al, 2015b). La faible intensité de fluorescence observée dans le diméthylsulfoxyde peut s'expliquer par de fortes interactions solvantsoluté (Thiaré et al, 2015b). L'étude de l'influence des solvants de polarité très différente a abouti au choix du méthanol qui est le solvant approprié pour la photodégradation car présentant l'intensité de fluorescence la plus élevée.…”

Section: Discussionunclassified

Etude des propriétés fluorescentes d’un naphtopyranone isolé de <i>Guiera senegalensis</i>

Mbow¹,

Thiaré²,

Ndiaye³

et al. 2017

Int. J. Bio. Chem. Sci

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Mots clés : Naphtopyranone, Guiera senegalensis, analyse par fluorescence, lumière UV. Study of the Fluorescent properties of a naphtopyranone isolated fromGuiera senegalensis ABSTRACT Guiera senegalensis is a plant used in therapeutic in Senegal and in several countries of West Africa. This justifies the development of photochemical methods of analysis of the isolated fluorescent naphtopyranone of this plant. Thus, these types of compounds could be analyzed from biological fluids and facilitate the pharmacological study. The influence of pH and several solvents of different polarity on the fluorescence intensity, the excitation and emission of naphtopyranone spectra were studied. This study allowed to draw calibration lines of the naphthopyranone, which leads to a calibration line strongly correlated. All analytical parameters that result were calculated. The results of irradiation were used to determine rate constant (k = 4,85.10 -2 min -1 ), half-life (t 1/2 =14,3 min), and order 1 of the kinetic of photodegradation. The low values of the limit of detection (LOD = 27 μg/mL) and quantification (LOQ = 250 μg/mL) shows a good sensitivity of this method of analysis and its possible application as a technique for qualitative and quantitative detection of these types of compounds in urine or blood.

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“…Where μ g and μ e are the ground and exited-state dipole moments, respectively, h is Planck's constant, c is the velocity of light, and a 0 is the radius of the molecule's Onsager cavity. The cavity radius for a dissolved substancea 0 -is calculated from Suppan's equation [45] (10):…”

Section: Time-correlated Single Photon Counting (Tcspc)mentioning

confidence: 99%

“…The polarization dependence and presence of hydrogen bonds in solvents are correlated with the polarity scale E N T . The theoretical basis for the correlation between the spectral shift and the E N T scale was provided by Ravi et al [45]. The E N T value is defined by Eq 13, where water (E N T ¼ 1) and tetramethylsilane (E N T ¼ 0) are used as the reference solvents:…”

Section: Time-correlated Single Photon Counting (Tcspc)mentioning

confidence: 99%

Spectroscopic and theoretical studies of fluorescence effects induced by the ESIPT process in a new derivative 2-Hydroxy-N-(2-phenylethyl)benzamide – Study on the effects of pH and medium polarity changes

et al. 2020

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The paper presents the results of studies conducted with the use of stationary and timeresolved fluorescence spectroscopy for the new derivative 2-Hydroxy-N-(2-phenylethyl) benzamide (SAL-3) in aqueous solutions with various concentrations of hydrogen ions as well as in solvent mixtures (i.e. media with changing polarity/polarizability). For the compound selected for the study placed in aqueous solutions with varying concentrations of hydrogen ions, the fluorescence emission spectra revealed a single emission band within most of the pH range, however, at low pH (pH<3) a significant broadening (noticeable effect of dual fluorescence) and shifting of the band was observed. Whereas, for water and polar (protic) solvents, we observed a very interesting phenomenon of dual fluorescence never before reported for this particular group of analogues (with the specific substituent system). Based on the results of the experiments, it was observed that the presented effects may be related both with conformational effects (related to the possible positioning of the-OH group on the side of the carbonyl system, which facilitates the possibility of proton transfer) as well as, most importantly, the effects of excited state intramolecular proton transfer (ESIPT-Excited State Intramolecular Proton Transfer) related in this case with the necessary (new/ previously unobserved in published literature) presence of ionic and non-ionic forms of the compound). Both the conducted quantum-mechanical [TD]DFT-Time-Dependent Density Functional Theory) calculations and excited state dipole moment change calculations for

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Determination of ground and excited state dipole moments of amino-benzimidazole by solvatochromic shift methods and theoretical calculations

Cited by 20 publications

References 22 publications

ESIPT-Related Origin of Dual Fluorescence in the Selected Model 1,3,4-Thiadiazole Derivatives

ESIPT-Related Origin of Dual Fluorescence in the Selected Model 1,3,4-Thiadiazole Derivatives

Etude des propriétés fluorescentes d’un naphtopyranone isolé de <i>Guiera senegalensis</i>

Spectroscopic and theoretical studies of fluorescence effects induced by the ESIPT process in a new derivative 2-Hydroxy-N-(2-phenylethyl)benzamide – Study on the effects of pH and medium polarity changes

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