Incorporation in Langmuir and Langmuir–Blodgett films of symmetric fluorine substituted bent-core liquid crystals: Morphological and optical properties

García-Vázquez, P.; Morales–Saavedra, Omar G.; Pelzl, G.; Bañuelos, J.G.; Carreón-Castro, María P.

doi:10.1016/j.tsf.2008.10.017

Cited by 12 publications

(7 citation statements)

References 33 publications

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“…Finally using eq , we can compute the second susceptibility χ (2) , which gives rise to the signal obtained through second harmonic generation measurements . With respect to the difference in orientation of the trans and cis isomers and referring to available surface pressure-molecular area isotherms measurements, strong differences in susceptibilities can be expected …”

Section: Resultsmentioning

confidence: 99%

“…77 With respect to the difference in orientation of the trans and cis isomers and referring to available surface pressure-molecular area isotherms measurements, strong differences in susceptibilities can be expected. 97 From the data depicted in Figure 7, the first striking result is that susceptibility values for the cis isomers are higher than the trans of at least 1 order of magnitude, making the cis isomers the active state in EFISHG. Once more, C3 isomers (both trans and cis) show a peculiar behavior for the reasons discussed above and starting from C6 we observe the presence of an inverse correlation for the trans isomer, where the susceptibility constantly decreases with an increasing tail length and with values in the 7−20 × 10 −36 esu range.…”

Section: ■ Methodsmentioning

confidence: 99%

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Push/Pull Effect as Driving Force for Different Optical Responses of Azobenzene in a Biological Environment

Knippenberg

Osella

2020

J. Phys. Chem. C

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The specific relationship between the alkyl tail lengths of four azobenzene probes embedded in DOPC liquid disorder membrane and their (non) linear optical (NLO) properties have been considered in the current study. Using extensive molecular dynamics calculations, the push/pull effect of the alkyl tails on the position and orientation of the probes in the model membrane are discussed. The simulations indicate that with increasing tail lengths the cis isomers are pushed closer to the membrane surface, while the trans ones are rather pulled toward the membrane center. Throughout hybrid quantum mechanics/molecular mechanics calculations, the linear and nonlinear optical properties of these compounds have been investigated. The pushing effect of the tails for cis azobenzene is translated in strong responses in the (non) linear optical spectroscopies, while the opposite is seen for the trans isomers. The cis isomer can be seen as the active state of the azobenzene compound for membrane recognition. The current work highlights the correlation between the tails of photosensitive membrane probes and their NLO properties, and focuses on unexpected behaviors of azobenzene derivatives in biological environments which can be exploited in distinguishing between soft and stiff cellular compartments that are of utmost importance for ion carrier transport.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Methodsmentioning

confidence: 99%

Push/Pull Effect as Driving Force for Different Optical Responses of Azobenzene in a Biological Environment

Knippenberg

Osella

2020

J. Phys. Chem. C

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“…Some of these studies have been focused on the behavior of such molecules at the air−water interface − although the molecular orientation has not been clearly elucidated in most of them. In addition, a few promising results have been obtained in the study of the optical and electrical properties of the LB films of these molecules. − …”

Section: Introductionmentioning

confidence: 99%

Molecular Arrangement in Langmuir and Langmuir−Blodgett Films of a Mesogenic Bent-Core Carboxylic Acid

et al. 2009

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A different alternative to previous research on Langmuir and Langmuir-Blodgett (LB) films of bent-core liquid crystals is reported in this work. A bent-shaped molecule wearing a terminal carboxylic group has been used to obtain monomolecular films with their long molecular axis almost perpendicular to the aqueous surface. Langmuir films at the air-liquid interface (pH=9) have been characterized by a combination of surface pressure and surface potential versus area per molecule isotherms, Brewster angle microscopy, and ultraviolet reflection spectroscopy. A condensed phase is reached at surface pressures up to 20 mN x m-1. In this condensed phase, molecules are packed forming H-aggregates with a well-defined molecular orientation. Langmuir films have been transferred onto quartz and silicon substrates and characterized by means of UV-vis spectroscopy and XRR. The transference is Z-type, with a constant deposition of the monolayers. The total LB monolayer film thickness is evaluated to be about 5.8 nm, which is in good agreement with the deduced orientation at the air-liquid interface as well as with the lamellar order observed within the solid obtained by cooling the sample from the mesophase.

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“…This special orientation effect has been observed for rigid-rod polymers, , rod-like crystals, stacks of disk-like molecules , and stretched two-dimensional flexible polymer networks . The in-plane anisotropy in LB films is of great interest as it offers the materials useful physical properties for potential applications as alignment layers of liquid crystals, , optical nonlinear waveguides, , matrices for orienting conductive guest molecules, and electronic and microelectronic materials. − …”

Section: Introductionmentioning

confidence: 91%

Dipping-Induced Azimuthal Helix Orientation in Langmuir−Blodgett Monolayers of α-Helical Amphiphilic Diblock Copolypeptides

et al. 2010

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The azimuthal helix orientation of the rigid-rod amphiphilic diblock copolypeptides (PLGA-b-PMLGSLGs) of poly(alpha-L-glutamic acid) (PLGA) and poly(gamma-methyl-L-glutamate-ran-gamma-stearyl-L-glutamate) with 30 mol % of stearyl substituents (PMLGSLG) in Langmuir-Blodgett (LB) monolayers was investigated using polarized transmission Fourier transform infrared spectroscopy. The relative position of dipping with respect to the previous transfer position can be used to manipulate the azimuthal orientation of the helices parallel to or tilted by an angle of 45 degrees with respect to the dipping direction in the transferred films. The study of the azimuthal order for the LB monolayers of PLGA-b-PMLGSLGs of various block lengths revealed that the observed effect arises mainly from the deformation of the PMLGSLG top brush layer, induced by the flow orientation around the transfer region. In those cases where the PMLGSLG block is tilted by a sufficiently large angle with respect to the surface normal, high azimuthal order parameters of 0.5-0.75 were obtained.

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Incorporation in Langmuir and Langmuir–Blodgett films of symmetric fluorine substituted bent-core liquid crystals: Morphological and optical properties

Cited by 12 publications

References 33 publications

Push/Pull Effect as Driving Force for Different Optical Responses of Azobenzene in a Biological Environment

Push/Pull Effect as Driving Force for Different Optical Responses of Azobenzene in a Biological Environment

Molecular Arrangement in Langmuir and Langmuir−Blodgett Films of a Mesogenic Bent-Core Carboxylic Acid

Dipping-Induced Azimuthal Helix Orientation in Langmuir−Blodgett Monolayers of α-Helical Amphiphilic Diblock Copolypeptides

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