The Hydrophobic Effect on the Adsorption of Rhodamines in Aqueous Suspensions of Smectites. The Rhodamine 3B/Laponite B System

Arbeloa, F. López; Martínez, J. M.; Arbeloa, and T. López; Arbeloa, Í. López

doi:10.1021/la971350a

Cited by 61 publications

(73 citation statements)

References 34 publications

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“…The metachromasy effect observed in the absorption spectrum of a dye/clay system, first reported by Bergmann and O'Konski (10) for the adsorption of methylene blue in montmorillonite, has been ascribed to the aggregation of dye as a consequence of the high local dye concentration at the clay surface (17)(18)(19), although an interaction between the electron π-system of the dye and the electron lone pair of oxygen atoms at the clay surface (20) has also been claimed. On the other hand, the adsorption of dye molecules in the interlayer space can be realized by two different mechanisms: the stacking of well-dispersed layers (as in the case of laponite particles, an octahedral substituted smectite) (18,21), or the migration of externally adsorbed species toward the interlayer space in relatively compact tactoids (as in the case of montmorillonite, a partially tetrahedral substituted smectite) (22,23). The migration is a slower process (time scale of days) than the stacking in which internally adsorbed species can been observed immediately after sample preparation.…”

Section: Introductionmentioning

confidence: 99%

Aggregation of Rhodamine 3B Adsorbed in Wyoming Montmorillonite Aqueous Suspensions

Arbeloa

Chaudhuri

Arbeloa

et al. 2002

Journal of Colloid and Interface Science

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Section: Introductionmentioning

confidence: 99%

Aggregation of Rhodamine 3B Adsorbed in Wyoming Montmorillonite Aqueous Suspensions

Arbeloa

Chaudhuri

Arbeloa

et al. 2002

Journal of Colloid and Interface Science

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“…It is interesting to mention in this context that absorption and intercalation of rhodamine 3B in various clays were studied by Lo´pez Arbeloa and co-workers [32][33]35] and found red shifts of the monomer absorption maximum by 7, 12, and 12.5 nm on montmorillonite, 10, 17, and 23 nm on Hectorite, and 10 nm on Laponite. The smaller shifts in montmorillonite and Hectorite were attributed to monomer absorption on the external clay surface and the intermediate shifts were attributed to monomer adsorption in the interlamellar regions, and the larger shifts were attributed to dimers or higher order aggregates.…”

Section: Spectroscopic Investigationmentioning

confidence: 93%

“…The adsorption of the dye in clay systems has generally been attributed to ion exchange [32][33][34][35][36], although Yariv et. al.…”

Section: Spectroscopic Investigationmentioning

confidence: 99%

Fluorescence Resonance Energy Transfer between organic dyes adsorbed onto nano-clay and Langmuir–Blodgett (LB) films

Hussain

Chakraborty

Bhattacharjee

et al. 2010

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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Abstract:In this communication we investigate two dyes N N ′ , -dioctadecyl thiacyanine perchlorate (NK) and octadecyl rhodamine B chloride (RhB) in Langmuir and Langmuir-Blodgett (LB) films with or with out a synthetic clay laponite. Observed changes in isotherms of RhB in absence and presence of nano-clay platelets indicate the incorporation of clay platelets onto RhB-clay hybrid films. AFM image confirms the incorporation of clay in hybrid films. FRET was observed in clay dispersion and LB films with and without clay. Efficiency of energy transfer was maximum in LB films with clay.Keywords: Fluorescence Resonance Energy Transfer (FRET), Langmuir-Blodgett, pressure-area isotherm, clay, dyes, Atomic Force Microscope (AFM). IntroductionFluorescence Resonance Energy Transfer (FRET) is a physical phenomenon first described over 50 years ago [1,2]. Due to its sensitivity to distance, FRET has been used to investigate molecular level interaction. Fluorescence emission rate of energy transfer has wide applications in biomedical, protein folding, RNA/DNA identification and their energy transfer process [3][4][5][6][7][8][9]. Another important application of energy transfer is in dye lasers. Dye lasers have some limitations as the dye solution used as an active medium absorbs energy from the excitation source in a very limited spectral range and so the emission band also has these limitations. If a dye laser has to be used as an ideal source its spectral range needs to be extended. In order to extend the spectral range of operation, mixtures of different dye solutions/dye molecules embedded in solid matrices are being used. The work on energy transfer between different dye molecules in such mixtures in various solvents and solid matrices is, therefore, of great importance. The use of such energy transfer in dye lasers is also helpful in minimizing the photo-quenching effects and thereby, increasing the laser efficiency.FRET is the relaxation of an excited donor molecule by transfer of its excited energy to an acceptor molecule

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“…Na literatura são encontrados diversos estudos envolvendo interações de corantes em sistemas micro-heterogêneos, tais como soluções contendo polieletrólitos 19,20 , ácidos nucléicos 21 , membranas lipídicas 22 , e suspensões de argilas [23][24][25][26][27][28][29][30][31][32][33][34][35] . Estes sistemas heterogêneos, agem como uma matriz de cargas que induz o ordenamento das moléculas de corante, reproduzindo interações do mesmo tipo que as observadas em soluções homogêneas mais concentradas.…”

Section: Corantes Em Meios Micro-heterogêneosunclassified

Interações entre corantes e argilas em suspensão aquosa

Neumann¹,

Gessner²,

Cione³

et al. 2000

Quím. Nova

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Recebido em 18/11/99; aceito em 16/3/00 INTERACTION BETWEEN DYES AND CLAYS IN AQUEOUS SUSPENSION.Adsorption of cationic dyes on clays can be used as a model for the interactions between organic compounds and these minerals. Cationic dyes like methylene blue are used to study these interactions because of the spectroscopic changes observed when their molecules are adsorbed on clay surfaces. Depending on the structure and layer charge of the clay particles several processes may occur, like adsorption of dye monomers and aggregates on the external and internal surfaces of the clay tactoids, migration towards internal surfaces, protonation, etc. Under certain conditions the deaggregation-aggregation of the clay particles are accelerated trapping dye species during these processes. A general scheme is proposed for the processes occurring between clays and dyes in aqueous suspensions, which can be used to explain the behaviour of specific systems.Keywords: cationic dyes; clays; clay-dye interactions. DIVULGAÇÃOAs interações de compostos orgânicos com argilas tem sido objeto de numerosas revisões da literatura 1,2 . O interesse nestes processos se direciona principalmente para o comportamento de herbicidas catiônicos 3 , fotoestabilização de complexos pesticidas-argilas 4 , moléculas de corantes orgânicos 5,6 e modificação hidrofóbica das superfícies de argilas.7 Por outro lado, as argilas podem servir como suportes e/ou catalisadores para vários tipos de reações e fotorreações. Cátions orgânicos participam de equilíbrio de troca iônica com a superfície das argilas, além de serem altamente seletivos, como mostram alguns estudos de adsorção competitiva 6 . A utilização de corantes como sondas é bastante interessante, já que são rapidamente adsorvidos pelas argilas e as diferentes espécies formadas após a adsorção são facilmente detectadas por técnicas espectroscópicas clássicas, como UV-VIS e fluorescência. A partir do conhecimento da espécie do corante formada durante o processo de adsorção, pode-se caracterizar os diferentes microambientes (sítios de adsorção) presentes em cada tipo de argilas. O conhecimento das características desses sítios tem grande importância, por exemplo, quando se deseja descrever a reatividade de algumas macromoléculas biológi-cas, como enzimas e proteínas, encontradas nos solos 8 , a ação de pesticidas e herbicidas 3,4 , e em geral todos os processos envolvendo solos. A mesma metodologia descrita, empregando corantes como sondas, é também aplicada ao uso de sistemas similares como zeolitas e silicatos 9 . ARGILAS 10-12A definição clássica designa argila como um material natural, terroso, de granulação fina que quando umedecido com água apresenta plasticidade. Os minerais constituintes das argilas são os argilominerais. Estes compostos são silicatos hidratados que possuem estrutura em camadas constituídas por folhas contínuas formadas por tetraedros de silício (ou alumí-nio) e oxigênio, e folhas formadas por octaedros de alumínio (magnésio ou ferro) e oxigênio e hidroxilas (Figura 1). 11Uma f...

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The Hydrophobic Effect on the Adsorption of Rhodamines in Aqueous Suspensions of Smectites. The Rhodamine 3B/Laponite B System

Cited by 61 publications

References 34 publications

Aggregation of Rhodamine 3B Adsorbed in Wyoming Montmorillonite Aqueous Suspensions

Aggregation of Rhodamine 3B Adsorbed in Wyoming Montmorillonite Aqueous Suspensions

Fluorescence Resonance Energy Transfer between organic dyes adsorbed onto nano-clay and Langmuir–Blodgett (LB) films

Interações entre corantes e argilas em suspensão aquosa

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