Towards a new class of ferroelectric liquid crystal molecules for nonlinear optical applications

Soldera, Armand; Theberge, René

doi:10.1080/02678290310001602012

Cited by 8 publications

(6 citation statements)

References 15 publications

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“…[4] However, challenges remain in the incorporation of such chromophores into stable, ordered assemblies capable of exploiting the large nonlinearities designed within the molecular frame. Several approaches have met with reasonable success, [5][6][7][8][9] with electric field poling arguably finding the most widespread use. [10][11][12] In practice, the net activity of poled films is often reduced over time due to relaxation within the polymer lattice to more thermodynamically favored isotropic orientations of molecular chromophores.…”

Section: Introductionmentioning

confidence: 99%

DNA‐Based Polymers as Chiral Templates for Second‐Order Nonlinear Optical Materials

et al. 2009

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The unique symmetry properties of chiral systems allow the emergence of coherent second harmonic generation in polymeric materials lacking polar order. Deoxyribonucleic acid (DNA) treated with the surfactant cetyltrimethylammonium (CTMA) was drop-cast to spontaneously form films that are active for coherent second harmonic generation (SHG). SHG images acquired as a function of incident and exigent polarization are in good agreement with theoretical predictions assuming nonpolar D(infinity) symmetry for the double-stranded DNA chains. Doping the DNA films with crystal violet substantially increases the efficiency of SHG, but does not significantly alter the polarization-dependence, suggesting that the SHG generated upon doping arises from the same chiral-specific origin, presumably templated by the DNA. These results raise the possibility of new design strategies for organic nonlinear optical materials based on soft chiral polymers that do not require polar order.

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Section: Introductionmentioning

confidence: 99%

DNA‐Based Polymers as Chiral Templates for Second‐Order Nonlinear Optical Materials

et al. 2009

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“…These empirical rules offer general guidelines for the synthesis of mesogens . They were of particular interest to get mesogens displaying the largest domain of thermal stability of the smectic C (SmC) phase for ferroelectric liquid crystal applications or nonlinear optical applications. − This mesophase is generally recognized to be fostered by the increase in the lengthening of the rigid core or the lateral alkyl chains . Thanks to the development of computer resources and efficiency of codes, molecular simulation became a valuable tool to capture these effects .…”

Section: Introductionmentioning

confidence: 99%

New Insights into the Thermal Stability of the Smectic C Phase

et al. 2014

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Subtle differences in the molecular structure of mesogens can lead to very different experimental polymorphisms. The smectic C (SmC) phase can actually be exhibited by one isomer and not the other, or the range of temperature can be completely different. Unveiling the deep connection between atomic structure and the very existence of the SmC phase will lead to the design of new performing liquid crystalline materials for ferroelectric or nonlinear optical applications. Our approach is based on running molecular dynamics simulation from an initial SmC arrangement of molecules. When the temperature is increased, the molecules automatically adjust in a more favorable organization. Such modification in the imposed initial self-assembly is governed by values of the nonbonded energies. Thanks to the combined use of simulation and experimental phase diagrams, we have unveiled part of the deep connection between atomic structure and the very existence of the SmC phase. The actual display of the SmC mesophase stems from a subtle balance between short-range interactions, which reveal arrangement of molecules within a smectic layer, and long-range interactions, which disclose organization of layers.

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“…Thus, the molecular structures of LC molecules are still quite simple, and there remains plenty of room for optimizing the structures in order to maximize the NLO properties in view of targeted applications. For instance, Soldera et al proposed in 2003 to attach a chiral sulfinate center directly on the NLO-phore, and a subsequent theoretical investigation was carried out to assess the impact of substituting the phenyl ring bearing the sulfinate group by donor and acceptor groups . Such a procedure was not applied to banana-shaped mesogens, though their study constitutes an actual new field of LC research.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, the structure–NLO property relationships are derived for two series of banana-shaped mesogens bearing a pair of sulfinate or carboxyl groups between the NLO-phore and the rigid arms (Scheme ). Second harmonic generation (SHG) responses in bent-core LC were addressed by several groups, − in order to reveal the splayed polarization orientation. For instance, the study of Takezoe and co-workers concerned a bent-core LC similar to compound 1a where the terminal SR groups are replaced by SR* moieties with * standing for the presence of chirality.…”

Section: Introductionmentioning

confidence: 99%

“…An inherent link between the mesogens structures and the macroscopic properties is actually far to be established. An actual small change in the molecular architecture of the mesogen can greatly affect the thermal stability of the mesophases. , Alterations brought to the original molecules that display in their polymorphism the expected ferroelectric mesophase definitely yield a different LC polymorphism. Such a large chemical sensitivity to the occurrence of this particular mesophase cannot be clearly predicted.…”

Section: Introductionmentioning

confidence: 99%

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Theoretical Design of the Molecular Structure of Bent-Core Mesogens with Large Second-Order Nonlinear Optical Properties.

et al. 2012

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The first hyperpolarizability of two series of molecules with bent-shaped structures has been calculated at the ab initio level. The two series consist of carboxyl derivatives for which some molecules are known to exhibit banana phases and of their sulfinate homologues that have not been synthesized yet. The final purpose is to reveal the relevance or not in synthesizing these latter molecules. The strategy is based on reporting the effect of the positions of donor and acceptor groups on the central benzene ring on the structural parameters and on the first hyperpolarizabilities. It is shown that in the sulfinate series the larger first hyperpolarizabilities are incompatible with efficient geometrical character while for the carboxyl series, the opening angle between the molecular arms is typical of banana-shaped molecules but the first hyperpolarizability is only slightly enhanced. Calculations thus reveal that the sulfinate series does not need to be synthesized, whereas they show that our approach can be naturally applied to the development of new bent-shaped molecules for nonlinear optical applications.

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Towards a new class of ferroelectric liquid crystal molecules for nonlinear optical applications

Cited by 8 publications

References 15 publications

DNA‐Based Polymers as Chiral Templates for Second‐Order Nonlinear Optical Materials

DNA‐Based Polymers as Chiral Templates for Second‐Order Nonlinear Optical Materials

New Insights into the Thermal Stability of the Smectic C Phase

Theoretical Design of the Molecular Structure of Bent-Core Mesogens with Large Second-Order Nonlinear Optical Properties.

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