Adsorption Of Cyanine Dyes Research Articles

Influence of the alkyl chain length of cyanine dyes on their adsorption by Na+-montmorillonite from aqueous solutions

Adsorption of cyanine dyes from aqueous solution onto the surface of Na+-montmorillonite (Na+-MMT) was investigated spectrophotometrically. A set of four linear alkyl chain cyanine dyes (D-C5, D-C7, D-C10, and D-C18), were used in this work to evaluate the effect of carbon chain length on the efficiency of dye adsorption. The loading of the dye onto Na+-MMT surface was increased with increasing the length of alkyl chain. The effect of the contact time, initial concentration of the dye, pH of solution and temperature on the adsorption process were studied. Adsorption isotherms were established and found to correlate well with the Freundlich, Langmuir, and Dubinin–Radushkevich adsorption models. Values of the constants Kf and 1/n determined from the Freundlich isotherm decreased with the increase in the tail length of the dye (D-C5→D-C18). The same trend was observed for the Langmuir adsorption constant, KL. The E values calculated from Dubinin–Radushkevich isotherm increased with increasing the alkyl chain length of the cyanine dyes but still less than 16kJmol−1, suggesting physical adsorption process. Further, the thermodynamic parameters (the enthalpy, ΔH, Gibb’s free energy, ΔG, and entropy, ΔS) characteristics of Na+-MMT/dye interaction were evaluated. The adsorption of cyanine dyes onto Na+-MMT was not spontaneous and endothermic. The magnitudes of ΔH and ΔS have dropped on going from D-C5 to D-C18. In contrast, as the size of the alkyl tail on the dye increased, Gibb’s free energy ΔG was decreased. As far as the adsorption kinetics is concerned, the present adsorption regime followed pseudo-second-order kinetic model rather than pseudo-first-order model. The intraparticle diffusion model resulted in the existence of both the bulk and intraparticle diffusions of the dye molecules into the interior pore surface of Na+-MMT particles.

Adsorption of Cyanine Dyes on Gold Nanoparticles and Formation of J-Aggregates in the Nanoparticle Assembly

This paper describes the results of an investigation of the interparticle interactions and reactivities in the assembly of gold nanoparticles mediated by cyanine dyes. The combination of the positively charged indolenine cyanine dyes and the negatively charged gold nanoparticles is shown to form a J-aggregate bridged assembly of nanoparticles, in addition to hydrophobic interparticle and electrostatic dye-particle interactions. Such interparticle interactions and reactivities are studied by probing the absorption of J-aggregates and fluorescence from the dyes and the surface plasmon resonance absorption from the nanoparticles. The J-aggregation of the dyes adsorbed on the nanoparticles is shown to play an important role in the assembly of nanoparticles. The spectral evolution of the J-band of the dyes and the surface plasmon resonance band of the nanoparticles was found to be sensitive to the nature of the charge and the structure of the dyes. The fluorescence quenching for the dyes was shown to be quantitatively related to the surface coverage of the dyes on the nanocrystal surfaces. These findings have provided important information for assessing a two-step process involving a rapid adsorption of the dyes on the nanoparticles and a subsequent assembly of the nanoparticles involving a combination of interparticle J-aggregation and hydrophobic interactions of the adsorbed dyes. The results are discussed in terms of the structural effects of the dyes, and the interparticle molecular interactions and reactivities, which provide important physical and chemical insights into the design of dye-nanoparticle structured functional nanomaterials.

Recent Studies on Surface Structure and Adsorption of Cyanine Dye J- aggregates on Silver Bromide Microcrystals Grown in Gelatin

Recent Studies on Surface Structure and Adsorption of Cyanine Dye J- aggregates on Silver Bromide Microcrystals Grown in Gelatin

Adsorption of cyanine dyes and optical properties of phosphatidic acid Langmuir monolayers and Langmuir-Blodgett films

The optical properties and the aggregate structure are investigated for phosphatidic acid (PA) Langmuir films adsorbing cyanine dyes from the aqueous solution to the air-water interface and for PA Langmuir-Blodgett (LB) films containing the dyes on glass substrates. H ∗ aggregation of the dyes oriented perpendicularly to the water surface is observed for the PA Langmuir films for subphases at pH 5. The H ∗ aggregate, however, is not observed after the LB films are deposited onto the substrates, and J aggregates appear instead. Aggregate properties of the dyes in the PA Langmuir films and the LB films depend on the pH of the subphase and are different from those of the dyes absorbed in arachidic acid (C20) films. Furthermore, absorption peaks of the aggregate models, calculated using the extended dipole model, coincide with the experimental absorption spectra. The properties are of great interest for controlling the characteristics of LB films adsorbing dyes and fabricating LB devices.

Aggregation of cyanine dyes at Langmuir-Blodgett monolayers

Cyanine dyes are adsorbed from aqueous solution to Langmuir-Blodgett (LB) films, forming monolayers of Scheibe or J aggregates, whereas the dye in solution is in monomeric state. As well as J aggregates other types of aggregates (H, H ∗ aggregates, oligomers, dimers) can form and interchange at the LB interface depending on conditions and the structures of the dyes and amphiphiles. Reflection spectroscopy proved to be a useful method for studying aggregates and kinetic processes at the air-water interface as the bulk subphase is not recorded by this method. Aggregation of dyes seems to be controlled by Coulomb interactions and the surface structure of the interacting monolayers. Cationic cyanine dyes are adsorbed only at negatively charged monolayers ( e.g. fatty acids) whereas cyanine dyes with negative net charge form aggregates only at positively charged monolayers ( e.g. amphiphilic ammonium salts). Aggregation of cyanine dyes has also been found at LB monolayers of amphiphilic nucleic acids which have been synthesized for the first time. Aggregates of adsorbed cyanine dyes can be transferred to solid substrates by the LB method and investigated by other spectroscopic methods or microscopy. Adsorption of cyanine dyes at vesicle bilayers has been reported; this was studied by absorption spectroscopy of vesicular dye solutions. Comparison of these spectra with reflection spectra of corresponding LB films reveals significant differences between the effects in LB monolayers and those in vesicular bilayers.

Surface-enhanced resonance raman study on adsorption of cyanine dye onto silver chloride colloids

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSurface-enhanced resonance raman study on adsorption of cyanine dye onto silver chloride colloidsJian Wang, Ping Zhang, Tianjing He, Houwen Xin, and Fanchen LiuCite this: J. Phys. Chem. 1988, 92, 7, 1942–1945Publication Date (Print):April 1, 1988Publication History Published online1 May 2002Published inissue 1 April 1988https://doi.org/10.1021/j100318a046RIGHTS & PERMISSIONSArticle Views241Altmetric-Citations35LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (492 KB) Get e-Alerts

Intermolecular Interaction in the Adsorption of Cyanine Dyes on Silver Halide Microcrystals

Intermolecular Interaction in the Adsorption of Cyanine Dyes on Silver Halide Microcrystals

Adsorption of cyanine dyes on AgCl crystals studied by XPS

Adsorption of 3,3'-dimethyl-9-ethylthiacarbocyanine dyes with iodide or bromide counter ions showed two energy states of sulfur in the dye molecule, one is the adsorption state to AgCl substrate and the other occurs when dye molecules aggregated. Though iodide conversion occurred on KI adsorption on AgCl, the counter ion of the dye molecule did not cause halide conversion on adsorption. The counter ion was observed only after the first dye monolayer on AgCl was completed, and increased parallel with adsorbed dye amounts. On Ag-deposited quartz plate monolayer formation occurred only by dye adsorption compared by its counter ion, while only iodine adsorbed in KI adsorption.

Adsorption of cyanine dyes on AgCl crystals studied by XPS

Adsorption of cyanine dyes on AgCl crystals studied by XPS

STUDY OF ADSORPTION OF SENSITIZING DYES ON SILVER BROMIDE BY CHRONOPOTANTIOMETRIC METHOD

The adsorption of dye on AgBr is investigated with a model of AgBr electrodeposited onAg electrode by using chronopotentiometric method and electronmicroscope. It has beenfound that there is an electroinertial complex formed after adsorption of cyanine dyes,the amount of which is to some extent correlated with its sensitizing ability. The stabi-lity of this kind of complex is quantitatively characterized by a conditional dissociation con-stant K', and the values of K' for several cyanine dyes have been calculated.

Adsorption of Cyanine Dyes and ζ - Potential at Silver Iodide Surface

The ζ -potential of negative silver iodide sols in the presence of cyanine dyes such as 1, 1'-diethyl-2, 2'-cyanine chloride, bromide, iodide and 4nitrate, was measured, together with the amount of the dyes adsorbed on the silver iodidepowder suspended in the same medium as the sols were.The ζ -potential increases rapidly with increasing dye concentration in a very low concentra-tion range (8x 10-8 -3x 10-7 mol/l). At higher concentrations, the z -potential increases slowly, reaching a constant value at 2∼ 5x 10-' mol/l (Fig.2). In the case of the bromide and iodide of the dye, however, the ζ -potential decreases gradually with the elapse of the time and approaches the value in the absence of the dye. The adsorption isotherm ofLangmuir type is obtained for the chloride, bromide and nitrate of the dye. As seen in Fig.3, however, the experimental points for the bromide salt vary widely. In the case of the iodide salt, the isotherm cannot be obtained, since the adsorption of the dye proceeds so long as the dye exists in the medium. These measurements were also made for the nitrate salt of the dye in the presence of gelatin, polyvinyl alcohol (PVA) or polyvinyl pyrrolidone (PVP). No influence of gelatin on the adsorption of the dye is recognized. PVA hindered the adsorption of the dye at low concentrations. In the presence of PVP, the amount of dye absorbed decreases. From these results, the adsorption behavior of the dyes on silver iodide was discussed.

Determination of Surface Areas of Silver Halide Suspensions by Adsorption of Cyanine Dye

AbstractA review of recent work shows close agreement on the molecular area of I, I'-diethy I-2,2'-cyanine adsorbed to silver bromide over a wide range of conditions. Very similar results have been obtained for samples with surface areas determined from electron-micrographs, by light scattering and by gas adsorption. The method of dye adsorption is therefore particularly good for determination of surface area. The work described in this paper indicates that the molecular area of the dye adsorbed to a silver iodide emulsion based on the surface area obtained from electronmicrographs is significantly lower than on silver bromide and cannot be accounted for by simple monolayer coverage. This is in agreement with previous work based on gas adsorption. Thus there appears to be no large discrepancy between the surface areas of silver iodide in aqueous solution and the areas obtained by gas adsorption as is suggested by the results of the negative adsorption method of van den Hul and Lyklema. The suggested value...

Adsorption of cyanine dyes at silver halide surfaces. Part 2.—Spectral properties and coverage

Adsorption isotherms and spectral reflectance measurements of four cyanine dyes adsorbed at silver-halide surfaces of known specific area showed that more dye was adsorbed from water than from alcohol and that each dye was adsorbed initially in an “unperturbed” form. Further adsorption of the dye from water, at points approaching the plateau of the isotherm, suggested that a second layer of dye was adsorbed on top of the first layer with a different orientation. The results were consistent with a first layer adsorbing flat-on and showing “unperturbed” spectral properties and a second layer was adsorbing side-on and showing “perturbed” properties. Some of these data are inconsistent with aggregation of the “perturbed” dye in the sense of cluster formation on the surface.

Adsorption of cyanine dyes at silver-halide surfaces

Adsorption of cyanine dyes at silver-halide surfaces