Solvatochromic betaine dyes of different hydrophobicity in ionic surfactant micelles: Molecular dynamics modeling of location character

Farafonov, Vladimir; Lebed, Alexander V.; Mchedlov‐Petrossyan, Nikolay O.

doi:10.1016/j.colsurfa.2017.11.046

Cited by 9 publications

(12 citation statements)

References 54 publications

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“…The final point is an inspection of the local environment of the dye molecule or, in other words, its microenvironment. For this sake, the previously described approach was employed [9][10][11]. The atoms located in 0.4 nm vicinity of either whole dye molecule or its chosen atom were distributed into 3 categories, namely, micelle hydrocarbon core, surfactant headgroups, and water; the average number of atoms in each category was computed.…”

Section: Resultsmentioning

confidence: 99%

“…GROMACS 5.0 software [15] was employed. The preparation of initial cells involved several stages and is in detail described in our previous papers [9,10].…”

Section: Simulation Methodologymentioning

confidence: 99%

“…The potential models for the dyes were built in the same way as the model for the standard dye [9,10]. For deriving the atomic point charges, we followed the standard OPLS-AA methodology.…”

Section: Simulation Methodologymentioning

confidence: 99%

“…For a more detailed review on the application and instrumental investigation of these dyes, the reader is addressed to ref. [9,10]. https://doi.org/10.26565/2220-637X-2018-30-03…”

Section: Introductionmentioning

confidence: 99%

“…In a set of previous papers, we made an attempt to reveal probable location and, thus, the nature of the microenvironment of several dyes within the micelles of cationic and anionic surfactants via molecular dynamics (MD) modeling [9][10][11]. Some most widely used pyridinium N-phenolates were already involved in the research project, such as the standard betaine dye I, 4-(2,4,6triphenylpyridinium-1-yl)-2,6-diphenylphenolate (R 1 = R 2 = R 3 = C 6 H 5 ) and three other compounds with different hydrophilicity/hydrophobicity: II (R 1 = R 2 = C 6 H 5 ; R 3 = H), III (R 1 = R 2 = C 6 H 5 ; R 3 = Cl), and IV [R 1 = R 2 = C 6 H 5 ; R 3 = C(CH 3 ) 3 ] [9,10]. Both colored (phenolate) and colorless (phenolic) forms were considered in micelles.…”

Section: Introductionmentioning

confidence: 99%

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An MD simulation study of Reichardt’s betaines in surfactant micelles: Unlike orientation and solvation of cationic, zwitterionic, and anionic dye species within the pseudophase

2018

Chemical Series

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Solvatochromic indicators of the pyridinium N-phenolate series, also known as Reichardt’s betaines, or Reichardt’s dyes, are often used for examining not only pure or mixed solvents, but also various colloidal aggregates, such as surfactant micelles, droplets of microemulsions etc. In order to disclose the locus of these molecular probes within the micellar pseudophase, we recently utilized the molecular dynamics (MD) simulations for the standard dye, i.e. 4-(2,4,6-triphenylpyridinium-1-yl)-2,6-diphenylphenolate, and three other dyes of this family of higher and lower hydrophobicity. Both zwitterionic (colored) and protonated (cationic, colorless) species were involved into the research, as these compounds are also used as acid-base indicators for micellar systems. In the present paper, we extended this investigation further. MD modeling was applied to another three dyes incorporated in sodium n-dodecyl sulfate and cetyltrimethylammonium bromide micelles. The following compounds were examined: (i) the most hydrophobic dye, bearing five tert-butyl groups, 4-[2,4,6-tri(4-tert-butylphenyl)pyridinium-1-yl]-2,6-di(4-tert-butylphenyl)phenolate, (ii) a dye with a hydrocarbon loop around the oxygen atom, 4-(2,4,6-triphenylpyridinium-1-yl)-n-(3,5-nonamethylene)phenolate, and (iii) the dye with additional carboxylate group attached to the phenyl group opposite to the phenol, 4-(4-carboxylatophenyl-2,6-diphenylpyridinium-1-yl)-2,6-diphenylphenol. The orientation and solvation of the cations, zwitterions (both colored and colorless), and the anion of the last-mentioned dye in micelles appeared to be dissimilar, depending on the molecular structure and ionization state. The results were compared with those obtained previously for the standard betaine dye. In some cases, the most probable orientation of the dyes in their colorless form was opposite to that of the standard Reichardt’s dye, i.e., their OH group is directed towards the center of the micelle.

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Section: Resultsmentioning

confidence: 99%

“…GROMACS 5.0 software [15] was employed. The preparation of initial cells involved several stages and is in detail described in our previous papers [9,10].…”

Section: Simulation Methodologymentioning

confidence: 99%

“…The potential models for the dyes were built in the same way as the model for the standard dye [9,10]. For deriving the atomic point charges, we followed the standard OPLS-AA methodology.…”

Section: Simulation Methodologymentioning

confidence: 99%

“…For a more detailed review on the application and instrumental investigation of these dyes, the reader is addressed to ref. [9,10]. https://doi.org/10.26565/2220-637X-2018-30-03…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

An MD simulation study of Reichardt’s betaines in surfactant micelles: Unlike orientation and solvation of cationic, zwitterionic, and anionic dye species within the pseudophase

2018

Chemical Series

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Localization of Hydrophobized Coumarin and Xanthene Acid–Base Indicators in Micelles

2022

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In search of an optimal acid-base indicator for examining surfactant micelles: Spectrophotometric studies and molecular dynamics simulations

Mchedlov‐Petrossyan

Farafonov

Cheipesh

et al. 2019

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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We report on combined experimental and theoretical investigations of the water/micelle interface of cationic, anionic, zwitterionic, and non-ionic surfactants using a new hydrophobic acid-base indicator 2,6dinitro-4-n-dodecylphenol. The indices of the so-called apparent ionization constant, app a pK , of the indicator fixed in the micellar pseudophase are determined by the spectrophotometric method. The data allows estimating the Stern layer's electrostatic potential of the ionic micelles . Molecular Dynamics modeling was used to locate the dye molecule and, in particular, its ionizing group OH  Owithin the micelles of the studied surfactants. The comparison of the  values estimated using 2,6-dinitro-4-ndodecylphenol with both our computer simulation and literature experimental results reveals obstacles in monitoring electrical interfacial potentials. In particular, the  values of the surfactant micelles with alkylammonium groups determined via 2,6-dinitro-4-n-dodecylphenol are overestimated. The reason is specific interactions of the indicator anion with the surfactant head groups. For anionic surfactants, however, this indicator is quite suitable, which is confirmed by the location of HA and Aequilibrium forms in the pseudophase.

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Solvatochromic betaine dyes of different hydrophobicity in ionic surfactant micelles: Molecular dynamics modeling of location character

Cited by 9 publications

References 54 publications

An MD simulation study of Reichardt’s betaines in surfactant micelles: Unlike orientation and solvation of cationic, zwitterionic, and anionic dye species within the pseudophase

An MD simulation study of Reichardt’s betaines in surfactant micelles: Unlike orientation and solvation of cationic, zwitterionic, and anionic dye species within the pseudophase

Localization of Hydrophobized Coumarin and Xanthene Acid–Base Indicators in Micelles

In search of an optimal acid-base indicator for examining surfactant micelles: Spectrophotometric studies and molecular dynamics simulations

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