Ionization and tautomerism of methyl fluorescein and related dyes

Mchedlov‐Petrossyan, Nikolay O.; Cheipesh, Tatyana A.; Shekhovtsov, Sergey V.; Red’ko, A. N.; Рыбаченко, В. И.; Omelchenko, Irina V.; Шишкин, Олег В.

doi:10.1016/j.saa.2015.05.037

Cited by 29 publications

(48 citation statements)

References 52 publications

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“…The signal in the region of δ = 167–168 ppm in both spectra unambiguously testifies to the presence of an aliphatic carbonyl carbon involved in the lactone cycle. For the lactonic form of methoxyfluorescein in DMSO‐d6 and dimethoxyfluoran in CDCl 3 , the corresponding signals are δ = 168.7 and 169.4 ppm, respectively. For the lactone of succinylfluorescein in DMSO‐d6, δ = 170.0 ppm .…”

Section: Resultsmentioning

confidence: 99%

“…The lactonic structure is confirmed by the signal of the nodal sp 3 C‐atom in ‐hybridisation: δ = 83.4 and 78.0 ppm for the dianion R 2− ( 5 ) and the neutral species H 2 R ( 1 ), respectively. For the methoxyfluorescein lactone and dimethoxyfluoran , δ = 82.7 and 83.2 ppm, respectively. For the lactone of succinylfluorescein and its diacetyl derivative, signals at δ = 80.3 and 79.6 ppm have been registered , whereas for the lactonic neutral structure of fluorescein and eosin in DMSO‐d6, values of δ = 83.5 and 81.0 ppm, respectively, have been reported .…”

Section: Resultsmentioning

confidence: 99%

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The molecular structure of anionic species of 2,4,5,7‐tetranitrofluorescein as studied by electrospray ionisation, nuclear magnetic resonance and X‐ray techniques

Mchedlov‐Petrossyan

Steinbach

Vodolazkaya

et al. 2018

Coloration Technology

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Among the fluorescein dyes, the behaviour of their nitro derivatives in solution is most unusual, and yet at the same time rarely studied. In this study, their 13 C nuclear magnetic resonance and electrospray spectra are reported, which confirm, in concert with their ultraviolet-visible spectra, the molecular structures of the neutral and ionic species of 2,4,5,7-tetranitrofluorescein observed in different solvents and at various pH values. A peculiar property of this dye consists in its lactonisation of the double-charged anion, contrary to the wellknown coloured and fluorescent dianions of fluorescein, eosin, etc. Also, this dianion-lactone exhibits high ability for opening the pyran ring. This cleavage takes place at much lower pH values as compared with those for fluorescein and its halogen derivatives. The ruptured species can be formed as either lactone or carbinol; the latter appears as a result of the nucleophilic attack of a HO À on the central carbon atom. The corresponding molecular structures are identified via the electrospray method and X-ray analysis. The behaviour of some other nitrofluoresceins in alkaline media is also considered. Coloration TechnologySociety of Dyers and Colourists † Just now, an article "Syntheses of novel acid-base indicators by nitration of phenolphthalein and fluorescein" by Y. Negishi,

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

The molecular structure of anionic species of 2,4,5,7‐tetranitrofluorescein as studied by electrospray ionisation, nuclear magnetic resonance and X‐ray techniques

Mchedlov‐Petrossyan

Steinbach

Vodolazkaya

et al. 2018

Coloration Technology

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“…The fluorescence of BBDMAF , which was expected to increase at pH < 3 due to further suppression of PET, decreased due to the formation of the ammonium xanthene form, which shows very low absorption. In addition, the absorbance of BBDMAF increased in the pH region where the cationic xanthene form (dicationic form) prevailed because its absorption is known to be greater than that of the ammonium xanthene form [ 9 , 19 , 20 ]. Accordingly, we measured the absorption and emission spectra of BDMAF and BBDMAF at pH −0.30, −0.56, and −0.94 ( Figure S4 ).…”

Section: Resultsmentioning

confidence: 99%

5-Bromo-4′,5′-bis(dimethylamino)fluorescein: Synthesis and Photophysical Studies

et al. 2018

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In this study, three new fluorescein derivatives—5-bromo-4′,5′-dinitrofluorescein (BDNF), 5-bromo-4′,5′-diaminofluorescein (BDAF), and 5-bromo-4′,5′-bis(dimethylamino)fluorescein (BBDMAF)—were synthesized and their pH-dependent protolytic equilibria were investigated. In particular, BBDMAF exhibited pH-dependent fluorescence, showing strong emission only at pH 3–6. BBDMAF bears a bromine moiety and thus, can be used in various cross-coupling reactions to prepare derivatives and take advantage of its unique emission properties. To confirm this, the Suzuki and Sonogashira reactions of BBDMAF with phenylboronic acid and phenylacetylene, respectively, were performed, and the desired products were successfully obtained.

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“…Numerous literature data reveal that the absorption bands of the cationic xanthene, neutral quinoid, and quinone‐phenolate forms of fluorescein are quite different (Figure S6) . Indeed, a broad single absorption band is typically observed for the cationic xanthene, a broad triple band (sometimes short‐wavelength shoulders are overlapped) for the neutral quinoid, and a broad double‐band for the negative quinone‐phenolate.…”

Section: Methodsmentioning

confidence: 99%

4′,5′‐Bis(dimethylamino)fluorescein Exhibits pH‐Dependent Emission Behavior Distinct From That of Fluorescein

2017

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4',5'-Diaminofluoresein (DAF)a nd 4',5'-bis(dimethylamino)fluorescein (BDMAF)h ave been synthesized and their pH-dependent photophysical properties and protolytic equilibria investigated. Although the parentf luorescein exhibits decreased emission upon decreasing pH, DAF displayed quenched emission at all pH values;s urprisingly, BDMAF exhibiteds trong fluorescenceo nly at pH 3-6, with its emission almost completely quenched under strongly acidic, neutral, and basic conditions. Fluorescein and its derivatives are used widely in modernb iochemical, biological,m edicinal, and photochemical research because of their excellent photophysical properties (Figure S1).[1] The light absorption and fluorescencep roperties of fluoresceind epend on the pH of the medium-the result of its containing acidic functional groups.[2] The protolytic equilibrium of fluorescein involves four species (cation, neutral, monoanion, dianion), with values of pK a of approximately 2, 4, and 6 (Scheme S1). Although the monoanionic and dianionic forms are the main ground-state species under biologically relevant conditions, their photophysical properties are quite distinct. For example, the absorbance of the monoanionic form is weak and its maximum is blue-shifted relative to that of the dianionic form. More importantly,t he fluorescencei ntensity of the monoanionic form is significantly lower than that of the dianionic form. Therefore, the pH of the mediumi sa ni mportant factor when studying systemsc ontaining fluorescein because it will exhibit weak emission intensity in aw eakly acidic environment. Because the value of pK a of the phenolic unit involved in the equilibrium between the monoanionic and dianionic forms in aqueous solutioni sa pproximately 6, close to the physiological pH, fluorescein derivatives containing electron-withdrawing groups (e.g.,halogen atoms on the xanthene ring) have been prepared previouslyi na ttempts to increase the acidity of the phenolic group.[3] Nevertheless, these compounds, like fluorescein,h ave exhibited pH-sensitivity problems of their own, with the fluorescencee missiond ecreasing upon decreasing the pH.Various intracellularo rganellesm aintain as teady pH, typically in the range from 5.0 (lysosomes)t o8 .0 (mitochondria).[4] In particular, there is increasing interesti nd eveloping efficient probesf or detecting the acidic pH induced by the active metabolism of cancer cells.[5] Therefore, we became interested in preparing fluoresceind erivativesd isplaying good fluorescence properties under acidic pH. We found recently that the introductiono fa mino or N,N-dimethylamino moieties on the fluorene ring led to significantly enhanced emissionsu nder acidic pH, relative to those under neutralo rb asic pH.[6] Some examples of fluoresceind erivatives having amino groups on the benzoica cid ring, rather than on the xanthene structure, have been reported, but their fluorescencei squenched at all values of pH. [7] 4',5'-Dimethyl-2',7'-diaminofluorescein is, to the best of our knowledge, the only exampl...

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Ionization and tautomerism of methyl fluorescein and related dyes

Cited by 29 publications

References 52 publications

The molecular structure of anionic species of 2,4,5,7‐tetranitrofluorescein as studied by electrospray ionisation, nuclear magnetic resonance and X‐ray techniques

The molecular structure of anionic species of 2,4,5,7‐tetranitrofluorescein as studied by electrospray ionisation, nuclear magnetic resonance and X‐ray techniques

5-Bromo-4′,5′-bis(dimethylamino)fluorescein: Synthesis and Photophysical Studies

4′,5′‐Bis(dimethylamino)fluorescein Exhibits pH‐Dependent Emission Behavior Distinct From That of Fluorescein

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