Role of guest-host intermolecular forces in photoinduced reorientation of dyed liquid crystals

Marrucci, Lorenzo; Paparo, D.; Maddalena, Pasqualino; Massera, Ettore; Prudnikova, Elena K.; Santamato, Enrico

doi:10.1063/1.475276

Cited by 80 publications

(80 citation statements)

References 32 publications

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“…Experimental visible absorption maxima, λ max , dichroic ratios, R, and dichroic order parameters, S exp , determined from the spectra shown in Figure 5. [34,36,37], and dye 1 itself has been reported to exhibit order parameters of 0.5 and −0.13 for the long-and short-wavelength bands, respectively, in a cyclohexyl-cyanophenyl host [35]. The long-wavelength band of the C 8 analogue of 3 is reported to have an order parameter of −0.33 in a nematic host [23].…”

Section: Resultsmentioning

confidence: 99%

“…These compounds each have n-butylphenyl substituents linked to the 1,4-positions of the anthraquinone by amine or amide linkages, providing a consistent set of structures to analyse. Compounds that are closely related to 1 have been reported to exhibit positive dichroic order parameters [34][35][36][37], whereas compounds that are closely related to 2 and 3 have been reported to exhibit negative dichroic order parameters [23].…”

Section: Introductionmentioning

confidence: 99%

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Guest–host systems containing anthraquinone dyes with multiple visible transitions giving positive and negative dichroic order parameters: an assessment of principal molecular axes and computational methods

et al. 2017

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(2017) Guest-host systems containing anthraquinone dyes with multiple visible transitions giving positive and negative dichroic order parameters: an assessment of principal molecular axes and computational methods. Liquid Crystals, Northumbria University has developed Northumbria Research Link (NRL) to enable users to access the University's research output. Copyright © and moral rights for items on NRL are retained by the individual author(s) and/or other copyright owners. Single copies of full items can be reproduced, displayed or performed, and given to third parties in any format or medium for personal research or study, educational, or not-for-profit purposes without prior permission or charge, provided the authors, title and full bibliographic details are given, as well as a hyperlink and/or URL to the original metadata page. The content must not be changed in any way. Full items must not be sold commercially in any format or medium without formal permission of the copyright holder. The full policy is available online: http://nrl.northumbria.ac.uk/policies.html This document may differ from the final, published version of the research and has been made available online in accordance with publisher policies. To read and/or cite from the published version of the research, please visit the publisher's website (a subscription may be required.)Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=tlct20 Three 1,4-disubstituted anthraquinone dyes with bis(4-n-butylphenyl) substituents connected via amine or amide linking groups have been studied as guest molecules dissolved in the nematic host E7. UV-visible absorption spectroscopy has shown each of the dyes to exhibit multiple absorption bands in the visible region, and dichroic order parameters obtained from polarised spectra of aligned guest-host samples were shown to differ significantly between the bands for each dye, and between the dyes. Time-dependent density functional theory calculations indicated that each dye exhibits several transitions, giving transition dipole moment vectors with a range of orientations, and fully atomistic molecular dynamics simulations of the guest-host mixtures showed differences in the calculated molecular alignments of the dyes. Combining the results from these two sets of calculations enabled a comparison of molecular alignment models based on the moments of inertia and the surface tensors of the dyes. The match between calculated and experimental values was improved significantly when using the surface tensor rather than the moment of inertia model, indicating that the shapes of the molecular surfaces of these dyes are crucial to their alignment. A novel method of calculating polarised UV-visible absorption spectra of dyes in liquid crystal hosts is also presented.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Guest–host systems containing anthraquinone dyes with multiple visible transitions giving positive and negative dichroic order parameters: an assessment of principal molecular axes and computational methods

et al. 2017

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“…For sufficiently small dye concentration, µ is independent both of it and of the dye absorption cross-section [29].…”

Section: λSmentioning

confidence: 99%

“…However, this quantity depends on the dye concentration and on the crosssection for light absorption. To characterize the single-dye-molecule efficiency in contributing to the torque after the absorption of a photon, the following merit figure µ has been introduced [29]:…”

Section: Jánossy's Model: Quantitative Comparison With Experimentsmentioning

confidence: 99%

Mechanisms of giant optical nonlinearity in light-absorbing liquid crystals: a brief primer

Marrucci¹

2002

Liquid Crystals Today

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“…[18][19][20][21][22][23][24][25][26][27] Molecular interactions are treated within mean-field approximation, where microscopic details such as the different shapes of the isomers are neglected.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Monte Carlo simulations for birefringence relaxation of photo-switchable molecules on a surface

Tavarone

Stark

2016

The Journal of Chemical Physics

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Recent experiments have demonstrated that in a dense monolayer of photo-switchable dye methyl-red molecules the relaxation of an initial birefringence follows a power-law decay, typical for glass-like dynamics. The slow relaxation can efficiently be controlled and accelerated by illuminating the monolayer with circularly polarized light, which induces trans-cis isomerization cycles. To elucidate the microscopic mechanism, we develop a two-dimensional molecular model in which the trans and cis isomers are represented by straight and bent needles, respectively. As in the experimental system, the needles are allowed to rotate and to form overlaps but they cannot translate. The out-ofequilibrium rotational dynamics of the needles is generated using kinetic Monte Carlo simulations. We demonstrate that, in a regime of high density and low temperature, the power-law relaxation can be traced to the formation of spatio-temporal correlations in the rotational dynamics, i.e., dynamic heterogeneity. We also show that the nearly isotropic cis isomers can prevent dynamic heterogeneity from forming in the monolayer and that the relaxation then becomes exponential. C 2016 AIP Publishing LLC. [http://dx

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Role of guest-host intermolecular forces in photoinduced reorientation of dyed liquid crystals

Cited by 80 publications

References 32 publications

Guest–host systems containing anthraquinone dyes with multiple visible transitions giving positive and negative dichroic order parameters: an assessment of principal molecular axes and computational methods

Guest–host systems containing anthraquinone dyes with multiple visible transitions giving positive and negative dichroic order parameters: an assessment of principal molecular axes and computational methods

Mechanisms of giant optical nonlinearity in light-absorbing liquid crystals: a brief primer

Kinetic Monte Carlo simulations for birefringence relaxation of photo-switchable molecules on a surface

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