UV absorption spectra of azobenzene-containing long-chain fatty acids and their barium salts in spread monolayers and Langmuir-Blodgett films

Kawai, Takeshi; Umemura, Junzo; Takenaka, Tohru

doi:10.1021/la00090a020

Cited by 138 publications

(115 citation statements)

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“…For compression beyond this point, we observed the appearance of the domains of much higher brightness surrounded by interference rings, which is shown in Fig. 1(b) (2). With the decrease of A, the number of domains rises.…”

Section: Bam Images Of Langmuir Filmsmentioning

confidence: 72%

“…The behaviour of 3/8CB film is different. Already at p = 0 (1) in the foam−like structure bright shimmer areas with ir− regular boundaries are seen, which exist also beyond the collapse point (2). The creation of the circular domains is also seen (2-4), but they do not pack together, solely their brightness increases.…”

Section: Bam Images Of Langmuir Filmsmentioning

confidence: 98%

“…Before the surface pressure starts to rise (1), a foam−like structure is observed, meaning coexistence of gas and liquid phases. Further compression makes the film completely homoge− neous (2). After the collapse point small domains appear (2), which grow continuously as the monolayer is further compressed.…”

Section: Bam Images Of Langmuir Filmsmentioning

confidence: 99%

“…In par− ticular, they display intriguing optical properties and there− fore can find application as novel functional materials for molecular electronics and photonics. Well known groups of dyes, which molecules have tendency to aggregation al− ready in the ground electronic state, are azo dyes [1][2][3][4]. These dyes are characterized by high value of hyperpolari− zability and, incorporated into highly oriented matrices, can find application in nonlinear optics [5].…”

Section: Introductionmentioning

confidence: 99%

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Molecular organization and aggregation in Langmuir and Langmuir-Blodgett films of azo dye/liquid crystal mixtures

Inglot

Martyński

Bauman

2009

Opto-Electronics Review

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A study of azo dye/liquid crystal mixtures in monolayers formed at air-water (Langmuir films) and air-solid substrate (Langmuir-Blodgett films) interfaces was performed. Three azo dyes with various molecular structure and two liquid crystal materials: 4-octyl-4′-cyanobiphenyl (8CB) and trans-4-octyl(4′-cyanophenyl)-cyclohexane (8PCH) were used. The morphology of Langmuir films was monitored by means of a Brewster angle microscope (BAM). Moreover, a surface pressure and electronic absorption spectra of the monolayer spread on the water surface of dye/liquid crystal mixtures as a function of a mean molecular area were simultaneously recorded. In addition, the absorption for Langmuir-Blodgett films deposited on quartz plates was measured. Information about intermolecular interactions in the mixtures of the nonamphiphilic dye and the liquid crystal with polar terminal group was obtained. Conclusions about the formation of self-aggregates between dye molecules have been drawn. The influence of the dye molecular structure and its concentration on aggregates’ geometry was found.

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Section: Bam Images Of Langmuir Filmsmentioning

confidence: 72%

Section: Bam Images Of Langmuir Filmsmentioning

confidence: 98%

Section: Bam Images Of Langmuir Filmsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Molecular organization and aggregation in Langmuir and Langmuir-Blodgett films of azo dye/liquid crystal mixtures

Inglot

Martyński

Bauman

2009

Opto-Electronics Review

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“…It is known that the hemicyanine group suffers H-aggregation at the air-water interface, [9][10][11][12][13][14][15] and therefore it is a suitable compound for the study indicated. The behavior of this mixed monolayer has been studied by using reflection spectroscopy, [16][17][18][19] Brewster angle microscopy (BAM), [20][21][22][23][24][25] as well as Grazing Incidence X-ray Diffraction (GIXD). 5,[26][27][28][29][30] The BAM technique has revealed an exciting large variety of morphological textures, also designated as condensed phase domains.…”

Section: Introductionmentioning

confidence: 99%

Control of the Lateral Organization in Langmuir Monolayers via Molecular Aggregation of Dyes

et al. 2010

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This paper shows that it is possible to construct well-defined 2D structures at the air-water interface in which the lateral organization is controlled by means of the preparation of mixed films, and selecting the components so that there are attractive interactions between them. The goal here is to establish the lateral connection between components through self-aggregation of the dye. This can be achieved by selecting a suitable balance between the sizes of the hydrophobic and polar groups. In such a way, the domain structure depends on the ability of the tilt dye to fill the available area. Thus, the molecular organization and the domain morphology of mixed films containing dimyristoyl-phosphatidic acid (DMPA) and the hemicyanine dye, 4-[4-(dimethylamino)styryl]-1-docosylpyridinium bromide (SP), have been studied by using Grazing Incidence X-ray Diffraction (GIXD), Brewster angle microscopy (BAM), and reflection spectroscopy at the air-water interface. For this mixed system, the formation of circular domains with bright horizontal regions and dark vertical regions was observed. Furthermore, depending on the temperature, it is observed as branches grow from circular domains, whose brightness depends on the growth direction. Thus, BAM images allow us to observe some branches that, as their growth direction changes, their brightness also changes simultaneously. The GIXD experiment permits us to relate the circular domains with an orthorhombic phase and the branches grown from the circles with an Overbeck phase. In both cases, the formed structures are induced by the hemicyanine aggregation. Circular BAM domain textures have been simulated by using the Fresnel equations for biaxial anisotropic materials.

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Preparation and characterisation of Langmuir-Blodgett films of 4-(4-(N-octadecyl-N-methylamino) phenylazo)benzoic acid

Szczur¹,

Munn²

1999

Adv. Mater. Opt. Electron.

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Langmuir films of the title compound have been spread on an aqueous subphase at various values of pH at 10, 15 and 20°C. Increasing pH and increasing temperature favour stable films, but at the higher subphase pH and temperature values the pressure–area isotherms exhibit a transition to aggregated forms. Tilt angles between the alkyl chains and the normal to the subphase increase with increasing subphase pH and temperature. The area per molecule for films deposited at 15 °C decreased steadily with time at a fixed surface pressure, except at the highest pH, indicating poor stability. Langmuir–Blodgett films deposited at a surface pressure of 30 mN m−1 and a subphase temperature of 15 °C were of Y‐type and showed transfer ratios above unity for the lower subphase pH values. UV/visible spectra of the LB films showed features characteristic of the formation of H aggregates for deposition at the higher subphase pH values. Over long periods of time the spectra for high pH showed evidence of increasing aggregation. Small‐angle X‐ray diffraction confirmed molecular tilts larger than those deduced in the floating monolayer. Reflection–absorption infrared spectroscopy of the LB films showed differences from the bulk also indicative of significant tilt, as did surface‐enhanced Raman spectroscopy. The LB films showed weak second‐harmonic generation from 1064 nm radiation consistent with a polar film structure parallel to the substrate. Copyright © 1999 John Wiley & Sons, Ltd.

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UV absorption spectra of azobenzene-containing long-chain fatty acids and their barium salts in spread monolayers and Langmuir-Blodgett films

Cited by 138 publications

References 1 publication

Molecular organization and aggregation in Langmuir and Langmuir-Blodgett films of azo dye/liquid crystal mixtures

Molecular organization and aggregation in Langmuir and Langmuir-Blodgett films of azo dye/liquid crystal mixtures

Control of the Lateral Organization in Langmuir Monolayers via Molecular Aggregation of Dyes

Preparation and characterisation of Langmuir-Blodgett films of 4-(4-(N-octadecyl-N-methylamino) phenylazo)benzoic acid

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