Effect of Solvent-Water Mixtures on the Prototropic Equilibria of Fluorescein and on the Spectral Properties of the Monoanion¶

Klonis, Nectarios; Sawyer, William H.

doi:10.1562/0031-8655(2000)0720179eoswmo2.0.co2

Cited by 16 publications

(11 citation statements)

References 26 publications

(60 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The citrate ion is the conjugate base of citric acid which has three acid groups and pK a values of 3.1, 4.8 and 6.4. 37,38 In particular, the latter value is similar to the dissociation constant of the carboxylic group of fluorescein (6.43), [39][40][41] which can result in a perturbation protolytic concentration of the dye which then affects the fluorescence behaviour. On the other hand cysteine molecules behave well as gold nanoparticle stabilizer 42,43 and they have pK a values (1.5, 8.7, 10.2) 44 different from the dye.…”

Section: Resultsmentioning

confidence: 95%

Effect of metal nanoparticles on the photophysical behaviour of dye—silica conjugates

Tarpani

Latterini

2014

Photochem Photobiol Sci

View full text Add to dashboard Cite

Fluorescein has been covalently entrapped into 120 nm silica beads in order to measure the effect of plasmonic gold nanoparticles, having 25 nm diameter, on the radiative processes of the dye. Two distinct regimes of enhancement and quenching of fluorescein emission have been observed, depending on the concentration of the metal adsorbed on the silica surface and the overlap between the SPR and the fluorescein spectra. At particle concentrations below 5.0 × 10(13) nanoparticles mL(-1), the fluorescence of the dye is enhanced, and this effect is more pronounced when the excitation wavelength matches the maximum of the extinction spectrum of the gold nanoparticles. When the concentration of gold is further increased, quenching occurs and it has been attributed to the SPR shift following the aggregation of the gold colloids on the silica surface. The invariance of the fluorescence lifetimes during the whole process indicates that the mechanism of fluorophore-nanoparticle interaction is mainly based on changes in the absorption efficiency of the organic dye.

show abstract

Section: Resultsmentioning

confidence: 95%

Effect of metal nanoparticles on the photophysical behaviour of dye—silica conjugates

Tarpani

Latterini

2014

Photochem Photobiol Sci

View full text Add to dashboard Cite

show abstract

“…Emission spectra were monitored at excitation wavelengths of 420 nm (········) and 455 nm (——). (c) The monoanion spectra were resolved from the spectra shown in (a) by subtracting an equivalent of 7.8% of the dianion spectra as described in Klonis and Sawyer (15)…”

Section: Resultsmentioning

confidence: 99%

“…These properties are consistent with spectral contributions arising from both the monoanion and the dianion species. Using the spectral resolution procedure we have previously described (15), it is possible to resolve the monoanion excitation and emission spectra (Fig. 2c).…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

The Thiourea Group Modulates the Fluorescence Emission Decay of Fluorescein-labeled Molecules ¶

Klonis¹,

Sawyer²

2007

Photochemistry and Photobiology

Self Cite

View full text Add to dashboard Cite

We have investigated the spectral properties and emission characteristics of fluorescein-5-thiocarbamoyl-N,N9-caproate (FITC-ACA) to examine the origin of the complex emission decay often observed in fluorescein-labeled molecules. The covalent attachment of fluorescein to e-amino-n-caproic acid does not perturb the prototropic transitions of the chromophore or the general fluorescence characteristics of the various prototropic forms. However, both the monoanion and dianion forms of FITC-ACA are quenched relative to free fluorescein and exhibit a complex emission decay that is described by two discrete lifetimes. The thiourea group that links the chromophore to the caproic acid is shown to modulate the emission properties of the FITC-ACA. We show that the emission decay can also be analyzed using the asymmetric distribution model of Alcala et al. In this analysis, the s L and s u parameters that represent the lower and upper lifetime limits of the distribution reflect the quenched (0 ns) and unquenched lifetimes, respectively. The b parameter that describes the distribution of lifetimes between the two limiting states can be related to the quenching efficiency of the thiourea group and to the structure and dynamics of the FITC-ACA molecule.

show abstract

“…Nonetheless, there are additional specific influences of an aqueous glycerol solution on fluorophores that are usually overlooked [8][9][10][11][12]. For instance, references [13][14][15][16] are highly informative regarding fluorescein in various solvents, although they do not consider fluorescein dissolved in aqueous glycerol. This in itself strengthens the argument that many users of glycerol in optophotospectroscopic measurements understand glycerol to be an innocent media.…”

Section: Introductionmentioning

confidence: 99%

Fluorophore spectroscopy in aqueous glycerol solution: the interactions of glycerol with the fluorophore

Feldman

Iron

Fixler

et al. 2021

Photochem Photobiol Sci

View full text Add to dashboard Cite

A common perception exists that glycerol provides an inert-like environment modifying viscosity and index of refraction by its various concentrations in aqueous solution. Said perception is herein challenged by investigating the effects of the glycerol environment on the spectroscopic properties of fluorescein, as a representative fluorophore, using steady-state and time-resolved techniques and computational chemistry. Results strongly suggest that the fluorescence quantum yield, measured fluorescence lifetime (FLT), natural lifetime and calculated fluorescence lifetime are all highly sensitive to the presence of glycerol. Glycerol was found to impact both the ground and first excited states of fluorescein, quenching and modifying both absorption and emission spectra, affecting the fundamental electrical dipoles of the ground and first excited singlet states, and lowering FLT and quantum yield. Furthermore, the Stern-Volmer, Lippert-Mataga, Perrin and Strickler-Berg relations indicate that glycerol acts upon fluorescein in aqueous solution as a quencher and alters the fluorescein geometry. Predictions made by computational chemistry impressively correspond to experimental results, both indicating changes in the properties of fluorescein at around 35% v/v aqueous glycerol, a clear indication that glycerol is not an innocent medium. This study proposes the Strickler-Berg relation as a means of detecting non-negligible effects of a hosting medium on its host fluorophore. These new insights on the molecular structures, the interactions between glycerol and its host fluorophore, and the effects of one on the other may be essential for understanding fundamental phenomena in chemistry and related fields.

show abstract

Effect of Solvent-Water Mixtures on the Prototropic Equilibria of Fluorescein and on the Spectral Properties of the Monoanion¶

Cited by 16 publications

References 26 publications

Effect of metal nanoparticles on the photophysical behaviour of dye—silica conjugates

Effect of metal nanoparticles on the photophysical behaviour of dye—silica conjugates

The Thiourea Group Modulates the Fluorescence Emission Decay of Fluorescein-labeled Molecules ¶

Fluorophore spectroscopy in aqueous glycerol solution: the interactions of glycerol with the fluorophore

Contact Info

Product

Resources

About