Effect of pi–pi stacking on the self-assembly of azomethine-type rod–coil liquid crystals

Liu, Yi; Zhan, Guo‐Dong; Zhong, Xinhui; Yu, Yingfeng; Gan, Wenjun

doi:10.1080/02678292.2011.589910

Cited by 26 publications

(19 citation statements)

References 42 publications

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“…ese polymers have been the focus of considerable research interest not only for their technological potential [11] but also on a more fundamental level because they exhibit a range of unusual liquid crystalline behaviour. is includes the dramatic dependence of their transitional properties on the length and parity of the �exible spacers linking the mesogenic units [12], the observation of a nematic-nematic transition [13], and the occurrence of alternating smectic phases [14]. Particularly, molecules containing azo groups are well known to show reversible isomerization transformations upon irradiation with ultraviolet and visible light [15,16].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Nonsymmetric Liquid Crystal Dimer Containing Biphenyl and Azobenzene Moiety

Subala¹,

Sundar²,

Sastry³

2012

Journal of Chemistry

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Calamitic liquid crystalline dimer containing azobenzene moiety and a decyloxy biphenyl linked by flexible spacers {4-[7-(4′-decyloxy-biphenyl-4-yloxy)-alkyloxy]-phenyl}-(4-decyl-phenyl)-diazene has been synthesized and characterized by spectroscopic methods. The transition temperatures and phase behaviours were studied by Differential Scanning Calorimeter (DSC) and Polarizing Optical Microscope (POM). The synthesized compounds exhibited enantiotropic liquid crystal phase with higher spacer display nematic and smectic C phases while lower spacer shows nematic and smectic A phases.

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Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Nonsymmetric Liquid Crystal Dimer Containing Biphenyl and Azobenzene Moiety

Subala¹,

Sundar²,

Sastry³

2012

Journal of Chemistry

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“…Similarly, Liu et al. Additionally, our TEM observation of needle-type Ir(ppy) 3 molecules in PVK:Ir(ppy) 3 binary system has not been introduced to date, except for Ir(ppy) 3 molecules in the P3HT, PF, and PFHP films [38][39][40][41]. More recently, Salim et al [39] suggested that the observation of needle-type Ir(ppy) 3 aggregates in ternary blend films was an indicator of the ability of Ir(ppy) 3 molecules to selfassemble into nanostructures even under spin-coating.…”

Section: Molecules and Host Materials Is Blurredmentioning

confidence: 52%

“…To resolve these issues, the EDS and HAADF techniques of ex-situ (S)TEM analysis were performed. The origin of needle-like features of guest molecules was systematically revealed in the earlier studies [37][38][39]. 7 devices (Fig.…”

Section: Molecules and Host Materials Is Blurredmentioning

confidence: 66%

“…2). [38] proved from the result of X-ray diffraction (XRD) that the π-stacking interaction in the solid state played an important role in highly ordered extended aggregation morphology of conjugated molecular systems. For instance, the needle-like aggregation of EPPTC molecules embedded in PFO film could be formed through π-stacking during a spin-coating process [37].…”

Section: Molecules and Host Materials Is Blurredmentioning

confidence: 99%

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Temperature-dependent nanomorphology–performance relations in binary iridium complex blend films for organic light emitting diodes

Kim

Seol

et al. 2015

Phys. Chem. Chem. Phys.

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Understanding the mechanism responsible for the temperature-dependent performances of emitting layers is essential for developing advanced phosphorescent organic light emitting diodes. We described the morphological evolution occurring in PVK:Ir(ppy)3 binary blend films, with respect to thermal annealing up to 300 °C, by coupling atomic force microscopy and transmission electron microscopy. In particular, in situ temperature-dependent experimental characterization was performed to directly determine the overall sequence of morphological evolution occurring in the films. The device thermally annealed at 200 °C exhibits a noticeable enhancement in the performances, compared to the devices in the as-processed state and to the devices annealed at 300 °C. Our approaches reveal that the Ir(ppy)3 molecules, with a needle-like structure in the as-processed state, were aggregated, and thus diffused into PVK without a morphological change at the temperature regime between 150 °C and 200 °C. Moreover, both network-like and droplet patterns existed in the devices annealed at 300 °C, which was beyond the glass temperature of PVK, leading to a profound increase in the surface roughness. The observed pattern formation is discussed in terms of viscoelastic phase separation. Based on our experimental findings, we propose that the performances of the devices are significantly controlled by the diffusion of dopant molecules and the morphological evolution of the host materials in binary blend systems.

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“…These systems are considered as targets in materials science not only because of their unique physicochemical properties, such as chemical flexibility [1], phase stability [2], semiconductor behavior [3], and intense nonlinear-optical responses [4], but also due to their intrinsic capability of self-organization [5]. The interpretation of physical measurements on LCs requires a suitable theory [6,7] for the response being measured in terms of observables.…”

Section: Introductionmentioning

confidence: 99%

Effect of Substituents on Electronic Spectral Shifts and Phase Stability of Liquid Crystalline Biphenylcyclohexane Molecules—A Theoretical Approach

Praveen¹,

Ojha²

2012

Molecular Crystals and Liquid Crystals

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d) basis set using crystallographic geometry as input. Using the optimized geometry, electronic structures of the molecules have been evaluated using the density functional theory (DFT) calculations. Mulliken atomic charges for each molecule have been compared with Loewdin atomic charges to understand the molecular charge distribution and phase stability. The electronic absorption spectra and circular dichroism (CD) spectra of BCH molecules have been simulated by employing the DFT method. The excited states have been calculated via configuration interaction single level (CIS) with semiempirical Hamiltonian ZINDO. Two types of calculations have been performed for model systems containing single and double molecules of BCHs. Further, the spectra have been reported for all single molecules, and the ultraviolet (UV) stability of the molecules has been discussed. The stacked and in-plane dimer complexes have also been reported to enable the comparison between single and double molecules.

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Effect of pi–pi stacking on the self-assembly of azomethine-type rod–coil liquid crystals

Cited by 26 publications

References 42 publications

Synthesis and Characterization of Nonsymmetric Liquid Crystal Dimer Containing Biphenyl and Azobenzene Moiety

Synthesis and Characterization of Nonsymmetric Liquid Crystal Dimer Containing Biphenyl and Azobenzene Moiety

Temperature-dependent nanomorphology–performance relations in binary iridium complex blend films for organic light emitting diodes

Effect of Substituents on Electronic Spectral Shifts and Phase Stability of Liquid Crystalline Biphenylcyclohexane Molecules—A Theoretical Approach

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