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Mchedlov‐Petrossyan, Nikolay O.; Isaenko, Yu.V.; Salamanova, Natalya V.; Alekseeva, V. I.; Savvina, L. P.

doi:10.1023/a:1027321019689

Cited by 11 publications

(15 citation statements)

References 9 publications

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“…9,11,39,40 In turn, for neutral red and malachite green similar spectral shifts were registered in micellar solutions and microemulsions of an anionic surfactant SDS, in aqueous solutions of anionic calixarens, in suspensions of liposomes. [9][10][11][12] Batochromic shift of 10 nm was observed for basic forms of eosin, ethyleosin, methyleosin, and uranin (disodium salt of fluorescein), captured in gelatin layer of photographic plates manufactured by Agfa (Agfa Gevaert graphic gelatin film, 61101508). 7 The alterations of l max give evidence for interaction of dyes with the gelatin gel.…”

Section: Spectral Characteristics Of Indicators Immobilized In the Gementioning

confidence: 52%

“…5) resemble to more or less extent those determined in micellar solutions of cationic surfactants, 9,40 cationic surfactant-based microemulsions, 11 and cationic calixarenes. 43 For the dye neutral red, the color transition occurs at pH values well above the pH ip .…”

Section: Apparent Ionization Constants Of Indicators In Two-phase Sysmentioning

confidence: 77%

“…[1][2][3][4][5][6][7] or using organized solutions, e.g., surfactant-based ones, [8][9][10][11][12] modifies the properties of guest molecules owing to the change of the microenvironment.…”

Section: Introductionmentioning

confidence: 99%

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Protolytic properties of dyes embedded in gelatin films

Никитина¹,

Reshetnyak²,

Svetlova³

et al. 2011

J. Braz. Chem. Soc.

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O filme de gelatina endurecida fixo em uma base transparente de triacetilcelulose pode ser utilizado como um suporte conveniente para indicadores ácido-base. Azul de bromofenol, verde de bromocresol, eosina, etil-eosina, n-decil-eosina, n-decil-fluoresceína, vermelho neutro e verde de malaquita foram incorporados nos filmes de gelatina por extração em meio aquoso sob condições apropriadas. A absorção de luz dos filmes dopados com corante exibe uma resposta ao pH de soluções tampão aquosas nas quais foram imersos. Valores reprodutíveis das constantes aparentes de dissociação dos indicadores, pK a app , foram calculados pelo tratamento convencional dos valores de pH do tampão aquoso e também para a água absorvida nos filmes de gelatina. Os experimentos com pH abaixo e acima do ponto isoelétrico da gelatina (em torno de pH 5) resultaram em valores de pK a app semelhantes àqueles em meios micelares de tensoativos catiônicos e aniônicos, respectivamente. Os filmes de gelatina modificados por corantes podem ser recomendados para uso em sensores óticos e dispositivos similares.The hardened gelatin film fixed on the transparent triacetylcellulose support can be utilized as a convenient carrier for acid-base indicator dyes. Bromophenol blue, bromocresol green, eosin, ethyleosin, n-decyleosin, n-decylfluorescein, neutral red, and malachite green were embedded into the gelatin films by extracting from aqueous media under appropriate conditions. The light absorption of dye-doped films exhibits a response to the pH values of aqueous buffer solutions, where they were soaked in. The well-reproducible indices of the apparent ionization constants, pK a app , of the indicators were calculated by conventional equating the pH values of the bulk aqueous buffer and those of the 'internal' water into the gelatin films. The experiments with pH below and above the isoelectric point of gelatin (around pH 5) result in pK a app values, which resemble those in micellar media of cationic and anionic surfactants, respectively. The dye-modified gelatin films can be recommended for use in optical sensors and related devices. Keywords: dye-modified gelatin film, indicators, apparent ionization constants, medium effects IntroductionThis paper is devoted to the influence of hardened gelatin media on the spectral and acid-base properties of immobilized xanthene, sulfonephthalein, and some other dyes.The immobilization of reagents in solid matrix (cellulose, ion-exchangers, polymers, silica, xerogels, etc.) 1-7 or using organized solutions, e.g., surfactant-based ones, [8][9][10][11][12] modifies the properties of guest molecules owing to the change of the microenvironment.Such modifications, or medium effects, are most studied and well documented for acid-base indicators. 8,9 In this case, the influence of the microenvironment results in the shift of the indicator equilibrium as compared to that in aqueous media. The main reasons are the local polarity and the local electrical charge. The latter often (but not always) manifests itself in the decre...

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Section: Spectral Characteristics Of Indicators Immobilized In the Gementioning

confidence: 52%

Section: Apparent Ionization Constants Of Indicators In Two-phase Sysmentioning

confidence: 77%

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Protolytic properties of dyes embedded in gelatin films

Никитина¹,

Reshetnyak²,

Svetlova³

et al. 2011

J. Braz. Chem. Soc.

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“…Continuing the study of the equilibria in direct (oilin-water) microemulsions [1], in this work we investigated acid3base properties of a series of solvatochromic betaines I3IV known as Reichardt dyes (Table 1) Protonation of the phenolate oxygen converts the colored forms of 4-(2,4,6-triphenyl-1-pyridinio)phenoxide (B) to colorless cationic form HB + . The apparent constant pK a a [1] characterizes equilibrium (1).…”

mentioning

confidence: 99%

“…It is known that, in binding betaines to surfactant micelles [7310], droplets of microemulsions [1,9], liposomes of phospholipids [7,10,11], or to the dispersed phase of surfactant-doped gels [12,13], the bathochromic shift of the low-frequency band against the aqueous solution can be as large as ca. 100 nm (negative solvatochromism) [3,14], and pK a a can vary by two and more units as compared to pK w a in the aqueous solution [7,8,11,13].…”

mentioning

confidence: 99%

Reichardt betaines as combined solvatochromic and acid-base indicators in microemulsions

2004

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Protolytic equilibria and absorption spectra of four solvatochromic Reichardt betaines different in their hydrophobicity are studied in direct microemulsions hydrocarbon3alcohol3surfactant3water (three different hydrocarbons, three alcohols, and seven surfactants including nonionic, cationic, and anionic ones were tested). Localization of even the most lipophilic betaines corresponds to the polarity index E N T of no less than 0.4, so that the occurrence of a purely hydrocarbon core in the microdroplets is unlikely probable. The apparent dissociation constants of the indicators are determined, and their dependence on the composition and concentration of the microemulsions is discussed.

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A novel probe for determination of electrical surface potential of surfactant micelles: N,N'‐di‐n‐octadecylrhodamine

Mchedlov‐Petrossyan

Vodolazkaya

Yakubovskaya

et al. 2007

J of Physical Organic Chem

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The peculiarities of the structure of the fluorescent dye N,N'-di-n-octadecylrhodamine advantage its using as an interfacial acid-base probe in aqueous micellar solution of colloidal surfactants. Two long hydrocarbon tails of the dye provide similar orientation of both cation and zwitterion on the micelle/water interface, with the ionizing group COOH exposed to the Stern region in all the systems studied. Further, the charge type of the acid-base couple, A þ B AE , ensures similar values of the 'intrinsic' contribution, pK i a , to the 'apparent' pK a a value in micelles of different surfactants. This makes the indicator suitable for determination of electrical surface potentials, C. The pK a a s have been obtained in cationic, anionic, zwitterionic, and nonionic surfactant systems, at various salt background. In total 17 systems were studied. At bulk counterion concentration of ca. 0.05 M, the pK a a values vary from 2.14 AE 0.07 in nÀC 18 H 37 NðCH 3 Þ þ 3 Cl À micelles to 5.48 AE 0.06 in nÀC 16 H 33 OSO À 3 Na þ micelles. The C values, corresponding to the Stern region of micelles, have been evaluated as C¼ 59:16 ðpK i a À pK a a Þ for T ¼ 298.15 K. The pK i a parameter was equated to the average value of 4.23 in nonionic surfactants (4.12-4.32, depending on the surfactant type). For cetyltrimethylammonium bromide and sodium n-dodecylsulfate micelles, the C values (AE(7-11) mV) appeared to be þ118 mVand at bulk Br À concentration 0.019 M and À76 mVat bulk Na þ concentration 0.020 M, respectively. This satisfactorily agrees with the theoretical values þ111 and À84 mV, estimated using the Oshima, Healy, and White equation for these well-defined colloidal systems. Finally, not only absorption, but also fluorescence spectra display the same response to changes in bulk pH.

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Cited by 11 publications

References 9 publications

Protolytic properties of dyes embedded in gelatin films

Protolytic properties of dyes embedded in gelatin films

Reichardt betaines as combined solvatochromic and acid-base indicators in microemulsions

A novel probe for determination of electrical surface potential of surfactant micelles: N,N'‐di‐n‐octadecylrhodamine

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