A spectroscopic study of the pH sensor response of fluorescein doped silica and aluminosilica sol-gel glasses

Shamansky, Lisa M.; Yang, Michael G.; Olteanu, Marta S. Fellows; Chronister, Eric L.

doi:10.1016/0167-577x(95)00214-6

Cited by 25 publications

(15 citation statements)

References 28 publications

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“…1 a y b). Este desplazamiento en la posición del máximo hacia el rojo, respecto del observado en el recubrimiento, es similar al encontrado por Shamansky [2], y posiblemente relacionado con un estado electrónico molecular más confinado, que se vería favorecido por la transición del estado sol al estado vítreo del recubrimiento, mucho más rígido. La forma lactónica de la fluoresceína en disolución presenta una mínima absorción [1,2] cerca de pH 3, que no resulta tan marcada en el recubrimiento, lo que sugiere que la red de sílice afecta la estructura y los niveles electrónicos de la fluoresceína encapsulada en los poros abiertos.…”

Section: Resultados Experimentales Y Discusiónunclassified

“…La fluoresceína es una molécula orgánica que en disolución lí-quida presenta importantes propiedades ópticas tanto de absorción como de luminiscencia, dando espectros característicos en la zona del visible, que se ven modificados con el pH [1,2,3]. Las propiedades de la fluoresceína han permitido que se utilice como marcador óptico en biología [4] y que actualmente se pretenda explotar como indicador óptico (absorción y luminiscencia) de pH [2,3,5].…”

Section: Introductionunclassified

“…Las propiedades de la fluoresceína han permitido que se utilice como marcador óptico en biología [4] y que actualmente se pretenda explotar como indicador óptico (absorción y luminiscencia) de pH [2,3,5]. En el desarrollo de sensores ópticos, la incorporación de moléculas orgánicas a una matriz porosa de tipo sol-gel [6][7][8] resulta ventajosa, ya que se evitan o disminuyen algunos de los inconvenientes de su uso en disolución, tales como procesos de contaminación y degradación de la molécula, procesos no radiativos, etc., además de ofrecer la posibilidad de ser reutilizados.…”

Section: Introductionunclassified

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Estudio de las propiedades ópticas de recubrimientos Sol-Gel dopados con fluoresceína en función de la concentración y del pH

García¹,

Montero²,

Broncano³

2004

Bol. Soc. Esp. Ceram. Vidr.

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Se investiga la variación con el pH de las propiedades ópticas (absorción y luminiscencia) de moléculas de fluoresceína incorporadas a recubrimientos porosos sol-gel en un intervalo de concentraciones comprendido entre 0,5 y 3, % en peso. Los espectros de absorción de los recubrimientos presentan bandas principales en 435 nm y 47 nm para pH ácido y básico, respectivamente. Al comparar con los espectros de las disoluciones, la posición de ambos máximos se desplaza hacia el rojo y aparecen en 43 nm y 492 nm. La dependencia de la absorción de la fluoresceína en recubrimientos y disoluciones se ajusta a la ley de Lambert-Beer. Al excitar los recubrimientos y las disoluciones con fotones de la región en que la absorción es importante, los espectros de fotoluminiscencia muestran una banda ancha principal en 520 nm, tanto para pH ácido como para básico. En este caso y contrariamente a lo observado en los espectros en disolución, la intensidad a 520 nm decrece con el pH al aumentar éste desde 2 a 12. Palabras clave: fluoresceína, pH, recubrimientos sol-gel, absorción, fotoluminiscencia Study of optical properties of fluorescein-doped sol-gel coatings as a function of concentration and pHOptical properties (absorption and luminescence) of fluorescein molecules encapsulated in porous sol-gel coatings for concentrations ranging from 0.5 to 3. wt % are investigated as a function of pH. Absorption spectra of the coatings show main bands at 435 nm and 47 nm for acid and basic pH, respectively. Both peaks appear in the solutions of fluorescein redshifted at 43 nm and 492 nm. However, the dependence in intensity of both peaks as a function of pH is found essentially similar between coatings and solutions. In both cases, the absorption dependence on concentration can be fitted to the Lambert-Beer law. On the other way, photoluminescent spectra of coatings and solutions upon excitation in the peak absorption region, show a dominant broad band peaked at 520 nm for both acid and basic pH. The intensity of the 520 nm-coating band displays a decreasing behaviour with increasing pH from 2 to 12, in contrast with those found for the same peak when the corresponding solutions were analysed.

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Section: Resultados Experimentales Y Discusiónunclassified

Section: Introductionunclassified

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Estudio de las propiedades ópticas de recubrimientos Sol-Gel dopados con fluoresceína en función de la concentración y del pH

García¹,

Montero²,

Broncano³

2004

Bol. Soc. Esp. Ceram. Vidr.

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“…In solution, the prototropic forms of fluorescein-like dyes are widely described to exist as an equilibrium between the various forms. The various forms reported in the literature are cationic, neutral form with three structures (quinoid, lactone, and zwitterionic), monoanionic, and dianionic [ 5 , 6 ]. Calculations for the determination of their electronic structure were carried out using computational methods [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

“…When considering potential applications and, consequently, designing materials with well-defined emission spectral range, tautomerization and prototropism of fluorescein and its derivatives are particularly problematic phenomena. The pH dependence of fluorescein-based materials prepared by sol–gel synthesis has already been studied for the ring-opened forms (product B) [ 5 , 22 ]. Our paper presents the possibility of doping SiO 2 -based layers with methylated derivative 1B.…”

Section: Introductionmentioning

confidence: 99%

Development of Efficient One-Pot Methods for the Synthesis of Luminescent Dyes and Sol–Gel Hybrid Materials

et al. 2021

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This paper presents a comparison of the simultaneous preparation of di-O-alkylated and ether–ester derivatives of fluorescein using different methods (conventional or microwave heating). Shortening of the reaction time and increased efficiency were observed when using a microwave reactor. Moreover, described here for the first time is the application of a fast, simple, and eco-friendly ball-assisted method to exclusively obtain ether–ester derivatives. We also demonstrate that fluorescein can be effectively functionalized by O-alkylation carried out under microwave or ball-milling conditions, saving time and energy and affording the desired products with good yields and minimal byproduct formation. All the synthesized products as well as pH-dependent (prototropic) forms trapped in the SiO2 matrix were examined using UV–Vis and fluorescence spectroscopy.

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Optical pH Sensor with Rapid Response Based on a Fluorescein‐Intercalated Layered Double Hydroxide

Shi

Wei

et al. 2010

Adv Funct Materials

116

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The preparation of a highly oriented photoluminescent film of fluorescein (FLU) and 1‐heptanesulfonic acid sodium (HES) co‐intercalated in a layered double hydroxide (LDH) matrix by electrophoretic deposition (EPD) is reported, and its application as an optical pH sensor is demonstrated. The FLU‐HES/LDH films with thickness ranging from nanometer to micrometer on indium tin oxide substrates exhibite good c‐orientation of LDH platelets (the ab‐plane of the LDH platelets parallel to the substrate), as confirmed by X‐ray diffraction and scanning electron microscopy. Polarized luminescence of the film is observed with anisotropy value r = 0.29, resulting from the highly oriented FLU in the LDH gallery. Furthermore, the optical pH sensor with film thickness of 300 nm exhibits a broad linear dynamic range for solution pH (5.02–8.54), good repeatability (relative standard deviation (RSD) less than 1.5% in 20 consecutive cycles) and reversibility (RSD less than 1.5% in 20 cycles), high photostability and storage stability (ca. 95.2% of its initial fluorescence intensity remains after one month) as well as fast response time (2 s). Therefore, this work creates new opportunities for the preparation and application of LDH‐based chromophores in the field of optical sensors.

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A spectroscopic study of the pH sensor response of fluorescein doped silica and aluminosilica sol-gel glasses

Cited by 25 publications

References 28 publications

Estudio de las propiedades ópticas de recubrimientos Sol-Gel dopados con fluoresceína en función de la concentración y del pH

Estudio de las propiedades ópticas de recubrimientos Sol-Gel dopados con fluoresceína en función de la concentración y del pH

Development of Efficient One-Pot Methods for the Synthesis of Luminescent Dyes and Sol–Gel Hybrid Materials

Optical pH Sensor with Rapid Response Based on a Fluorescein‐Intercalated Layered Double Hydroxide

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