Acidity Dependence of the Absorption and Fluorescence Spectra of Isoflavone and 7-Hydroxyisoflavone

Wolfbeis, Otto S.; Schipfer, Rudolf

doi:10.1111/j.1751-1097.1981.tb09404.x

Cited by 4 publications

(8 citation statements)

References 10 publications

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“…The absence of fluorescence and the presence of phosphorescence of N * indicates that the lowest excited state of this form is of nπ* type. Therefore, spectral properties of neutral 7HF are similar to those of flavone and isoflavone. − …”

Section: Discussionmentioning

confidence: 88%

7-Hydroxyflavone Revisited: Spectral, Acid–Base Properties, and Interplay of the Protolytic Forms in the Ground and Excited States

2014

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Spectral and acid-base properties of 7-hydroxyflavone (7HF) in the ground and excited states were investigated with a purpose to enable reasonable application of this dye and its derivatives as fluorescent probes. Analysis of solvatochromic and solvatofluorochromic ability of 7HF in 20 solvents, investigations of 7HF spectral properties in the frozen solvents, spectrophotometric and spectrofluorimetric titrations in methanol-water (4:1 v/v) in the wide pH/H0 range (from pH = 11.0 to H0 = -4.5), analysis of the 3D fluorescence and time-resolved spectra, as well as quantum-chemical calculations were carried out. It has been found that 7HF can exist in three protolythic forms-neutral, anion, and cation-depending on the environment acidity or basicity. In the excited state, in methanol-water solutions, there are four forms: neutral, cation and anion, which can be formed by direct excitation of the ground-state anion or by photodissociation of the neutral form depending on pH, and only one phototautomer, which appears in the H0 range from 1.3 to -4.5. It has been shown that the mechanism of the phototautomer formation depends on medium acidity. The photoautomer can be formed by cation photodissociation as well as by photoanion protonation. Finally, it was concluded which of the 7HF protolytic forms can be used for fluorescent probing.

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Section: Discussionmentioning

confidence: 88%

7-Hydroxyflavone Revisited: Spectral, Acid–Base Properties, and Interplay of the Protolytic Forms in the Ground and Excited States

2014

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“…For these molecules the large Stokes’ shift cannot be attributed to ESIPT because there are no acidic hydrogens in the immediate vicinity of the basic carbonyl group at C4. For isoflavones with an −OH substituent at C7, strong fluorescence was observed under basic conditions, which was attributed to the anionic form. ,, It was suggested that in the case of 7-hydroxyisoflavone (R = OH; R′ = H in Figure ) the emission at neutral pH can also occur from the excited-state anion due to the increased acidity of the 7-OH group in the excited state. On the other hand, the excitation spectra presented by Dunford et al on daidzein (R = OH; R′ = OH) at neutral pH indicated that the emission was mainly due to a small population of deprotonated molecules in the ground state.…”

Section: Introductionmentioning

confidence: 99%

Computational Study on the Anomalous Fluorescence Behavior of Isoflavones

Beyhan¹,

Götz²,

Ariese³

et al. 2011

J. Phys. Chem. A

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Isoflavones are known to show fluorescence with intensities that depend strongly on the solvent properties and exhibit Stokes' shifts as large as 1.4 eV. While some of this behavior can be explained by (excited state) deprotonation, this mechanism does not apply for all isoflavones. The aim of this study is to computationally and experimentally investigate the reasons for this anomalous behavior of neutral isoflavones, taking the daidzein molecule as a model compound. We find that the absence in fluorescence in aprotic solvents and the weak fluorescence in protic solvents can be explained by a change of order of the lowest singlet states in which a fluorescent charge-transfer state lies below the nonfluorescent locally excited state in water but not in acetonitrile. The large Stokes' shift is partly due to a significant rotation among the chromone-phenyl bond in the excited state.

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“…Rhodamine B and polyvinyl diphenylquinoline are tunable over tens of nm by changing the local pH 20 . 7-Hydroxy isoflavone can be tuned over approximately 35 nm in the blue–green region depending on the pH of the solution 21 . Exciplex structures formed from a coumarin derivative might lase over a range of wavelengths by adjusting the solution pH 22 .…”

Section: Introductionmentioning

confidence: 99%

Wide-gamut lasing from a single organic chromophore

et al. 2018

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The development of wideband lasing media has deep implications for imaging, sensing, and display technologies. We show that a single chromophore can be engineered to feature wide-gamut fluorescence and lasing throughout the entire visible spectrum and beyond. This exceptional color tuning demonstrates a chemically controlled paradigm for light emission applications with precise color management. Achieving such extensive color control requires a molecular blueprint that yields a high quantum efficiency and a high solubility in a wide variety of liquids and solids while featuring a heterocyclic structure with good steric access to the lone pair electrons. With these requirements in mind, we designed a lasing chromophore that encloses a lasing color space twice as large as the sRGB benchmark. This record degree of color tuning can in principle be adapted to the solid state by incorporating the chromophore into polymer films. By appropriately engineering the base molecular structure, the widest range of lasing wavelengths observed for a conventional gain medium can be achieved, in turn establishing a possible route toward high-efficiency light emitters and lasers with near-perfect chromaticity.

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Acidity Dependence of the Absorption and Fluorescence Spectra of Isoflavone and 7-Hydroxyisoflavone

Cited by 4 publications

References 10 publications

7-Hydroxyflavone Revisited: Spectral, Acid–Base Properties, and Interplay of the Protolytic Forms in the Ground and Excited States

7-Hydroxyflavone Revisited: Spectral, Acid–Base Properties, and Interplay of the Protolytic Forms in the Ground and Excited States

Computational Study on the Anomalous Fluorescence Behavior of Isoflavones

Wide-gamut lasing from a single organic chromophore

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