Surface potential measurements of Langmuir films of azo dye/liquid crystal mixtures

Inglot, Krzysztof; Martyński, Tomasz; Bauman, Danuta

doi:10.1016/j.dyepig.2008.05.013

Cited by 12 publications

(8 citation statements)

References 17 publications

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“…This means that none of the azo dyes under investigation cannot produce stable and compressible monolayer, although all they possess terminal and/or lateral polar group. Similar behaviour was noticed for azo dyes investigated previously [7][8][9][10]. However, when the dyes were mixed with 8CB at appropriate concentrations, the compression was possible and we obtained π-A isotherms.…”

Section: Surface Pressure and Surface Potential As A Function Of Meansupporting

confidence: 64%

“…This is rather unexpected result taking into account the fact that the molecules in the Langmuir films formed of the mixtures align more and more perpendicularly to the water surface with the increase of the dye content (see ϕ values in Table II). The same effect was observed for monolayers of other azo dyes mixed with liquid crystals [9,24] and was explained in terms of the opposite orientation of the dye dipole moments with respect to the dipole moments of the liquid crystal molecules. Such antiparallel alignment of the dipole moments leads to the diminishing of the resultant µ ⊥ value.…”

Section: Table IIsupporting

confidence: 48%

“…Some years ago in our laboratory the study of the molecular organization and aggregation in the Langmuir and Langmuir-Blodgett films formed of azo dyes mixed with a liquid crystal, using as a stabilizing matrix, had been undertaken [7][8][9][10]. Our present work, that was carried out as the continuation of the previous study, has aimed at reporting several additional observations related to the intermolecular interactions on the molecular level.…”

Section: Introductionmentioning

confidence: 48%

“…[9], we looked for the correlation between the value and the direction of the dipole moment of the given dye molecule and the diminishing of µ ⊥ values of the monolayer after the dye addition. Dyes 1, 3 and 4 have similar value of the dipole moment, with different directions of it.…”

Section: Table IImentioning

confidence: 99%

“…Figure 3a presents, reproduced from Ref. [9], the electric surface potential-area isotherm (solid curve), recorded simultaneously with the π-A isotherm (dotted curve), as well as the effective dipole moment-area isotherm (dashed curve) for the liquid crystal 8CB, which can be treated as a reference for the mixtures of azo dyes with 8CB. Exemplary results for the Langmuir films of 2/8CB and 5/8CB mixtures at X M = 0.3 are shown in Figs.…”

Section: Table IImentioning

confidence: 99%

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Molecular Interactions in Monolayers οf Azo Dye/Liquid Crystal Mixtures at Interfaces

2009

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A study of azo dye/liquid crystal mixtures in monolayers formed at an air-water interface (the Langmuir films) and at a solid surface (the Langmuir-Blodgett films) has been performed. Five azo dyes with various molecular structure and the liquid crystal 4-octyl-4 -cyanobiphenyl (8CB) have been used. The dyes have been added to the liquid crystal at various molar fractions. Surface pressure and surface potential versus mean molecular area isotherms for the Langmuir films have been recorded and information about intermolecular interactions at the air-water interface has been obtained. On the basis of electronic absorption measurements for the Langmuir and Langmuir-Blodgett films the conclusions about the ability of dyes molecules to form self-aggregates at the interfaces have been drawn. The influence of the dye molecular structure and its concentration on aggregates' geometry has been found.

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Section: Surface Pressure and Surface Potential As A Function Of Meansupporting

confidence: 64%

Section: Table IIsupporting

confidence: 48%

Section: Introductionmentioning

confidence: 48%

Section: Table IImentioning

confidence: 99%

Section: Table IImentioning

confidence: 99%

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Molecular Interactions in Monolayers οf Azo Dye/Liquid Crystal Mixtures at Interfaces

2009

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Push–pull bithiophene azo-chromophores bearing thiazole and benzothiazole acceptor moieties: Synthesis and evaluation of their redox and nonlinear optical properties

et al. 2011

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Three series of bithiophene azo dyes functionalized with thiazol-2-yl or benzothiazol-2-yl-diazene acceptor moieties were synthesized through azo coupling reaction using 2,2´-bithiophene, 5-alkoxy-2,2´-bithiophenes, 5-N,N-dialkylamino-2,2´-bithiophenes and thiazolyl and benzothiazolyl diazonium salts as coupling components. The 5-alkoxy-2,2´bithiophene precursors yielded the 5-thiazolylazo-5´-alkoxy-2,2´-bithiophenes, while the azo coupling reaction of 5-N,N-dialkylamino-2,2´-bithiophenes with the thiazolyldiazonium salt gave 4-thiazolyl-azo-5-N,N-dialkylamino-2,2´-bithiophenes. A different reactivity behavior was observed for 2,2-bithiophene with thiazolyl diazonium salts which gave rise to the expected azo dyes together with several arylation products. The redox behavior, thermal stability, and the first hyperpolarizability of the novel chromophores were evaluated through cyclic voltammetry, thermogravimetric analysis (TGA) and hyper-Rayleight scattering (HRS) respectively. By varying the position of the thiazolyldiazene acceptor group on the bithiophene system, the electrochemical behavior as well as the optical (linear and nonlinear) properties of the donor-acceptor -conjugated systems can readily be tuned. Push-pull 5thiazolylazo-5´-alkoxy-2,2´-bithiophenes exhibit the most promising redox and the solvatochromic properties and second order nonlinear optical response. The redox and the optical properties also show notable variations for the different heterocyclic spacers and were also sensitive to the electronic acceptor strength of the (benzo)thiazolyldiazene moieties.

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Thiazole azo dyes with lateral donor branch: Synthesis, structure and second order NLO properties

et al. 2013

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Surface potential measurements of Langmuir films of azo dye/liquid crystal mixtures

Cited by 12 publications

References 17 publications

Molecular Interactions in Monolayers οf Azo Dye/Liquid Crystal Mixtures at Interfaces

Molecular Interactions in Monolayers οf Azo Dye/Liquid Crystal Mixtures at Interfaces

Push–pull bithiophene azo-chromophores bearing thiazole and benzothiazole acceptor moieties: Synthesis and evaluation of their redox and nonlinear optical properties

Thiazole azo dyes with lateral donor branch: Synthesis, structure and second order NLO properties

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