Synthesis, LC self-assembly and photophysical behavior of stimuli responsive cyanostilbene-based hexacatenar mesogens with multicolour switching

Liang, Yurun; Liu, Xiaotong; Pu, Ying‐Chih; Zhang, Ruilin; Zhou, Limei; Xiao, Yulong

doi:10.1016/j.jlumin.2023.119977

Cited by 9 publications

(2 citation statements)

References 47 publications

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“…In fact, this change is not directly related to the phase transition. A reasonable explanation is that the low temperature leads to the decrease of fluidity, which reduces the energy loss caused by molecular collisions, and the aggregation of molecules leads to the change of color …”

Section: Resultsmentioning

confidence: 99%

“…A reasonable explanation is that the low temperature leads to the decrease of fluidity, which reduces the energy loss caused by molecular collisions, and the aggregation of molecules leads to the change of color. 39 The length of the flexible chains has a significant effect on the clearing point temperature (Figure 2). For both TPn-SA or TPn-S, the increase of the chain-length causes a decrease in the clearing temperature as commonly observed with similar compounds due to increase thermal agitation.…”

Section: ■ Introductionmentioning

confidence: 99%

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Dual-State Fluorescence in Some Salicylaldehyde-triphenylene Discotic Liquid Crystal Derivatives Induced by Excited State Intramolecular Proton Transfer

Zeng,

Wang,

Wang

et al. 2024

Chem. Mater.

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A new family of excited state intramolecular proton transfer (ESIPT) molecules based on the enol/ketone tautomerism is reported. The molecules were designed to display columnar mesophases and consist of the archetypical 3,6,7,10,11-penta(alkoxy)triphenylene discotic core functionalized in the vacant "2-position" by a salicylaldehyde group (TPn-SA). For comparison and confirmation that the ESIPT effect is solely due to the salicylaldehyde group, structurally related triphenylene derivatives bearing benzaldehyde (TPn-S) or aldehyde (TPS6) side groups were also synthesized. These molecules were synthesized either by Suzuki−Miyaura cross-coupling (TPn-SA, TPn-S) or by the Bouveault aldehyde synthesis (Ar−Li and DMF, TPS6) in overall good yields. All triphenylene compounds show an enantiotropic columnar hexagonal mesophase over large temperature range. Furthermore, TPn-SA compounds undergo a mesophase to crystalline phase transformation upon UV light irradiation at 365 nm, caused by ESIPT-induced enol− ketone tautomerism. TP12-SA also self-assembles into room temperature gels in toluene and ethyl acetate at rather low critical gel concentration. TPn-SA and TPn-S present strong fluorescence in both solution and solid state, with fluorescence quantum yields for the TPn-SA compounds around ∼20%; TPS6, in contrast, does not show fluorescence in solid state because of aggregation-caused quenching. The dual emission observed for TPn-SA was supported by DFT calculation. The ketone emission is dominant in nonpolar solvents and aggregated states, while the enol emission is dominant in polar solvents or in dilute solutions. Finally, the performances of TP6-SA and TP6-S in solid-state lighting LED devices have been investigated.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Dual-State Fluorescence in Some Salicylaldehyde-triphenylene Discotic Liquid Crystal Derivatives Induced by Excited State Intramolecular Proton Transfer

Zeng,

Wang,

Wang

et al. 2024

Chem. Mater.

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Phenanthrothiophene‐Triazine Star‐Shaped Discotic Liquid Crystals: Synthesis, Self‐Assembly, and Stimuli‐Responsive Fluorescence Properties

Zeng,

Deng,

Zhao

et al. 2024

Chemistry A European J

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Lipophilic biphenylthiophene‐ and phenanthrothiophene‐triazine compounds, BPTTn and CPTTn respectively, were prepared by a tandem procedure involving successive Suzuki‐Miyaura coupling and Scholl cyclodehydrogenation reactions. These compounds display photoluminescence in solution and in thin film state, solvatochromism with increasing solvent’s polarity, as well as acidochromism and metal ion recognition stimuli‐responsive fluorescence. Protonation of BPTT10 and CPTT10 by trifluoroacetic acid results in fluorescence quenching, which is reversibly restored once treated with triethylamine (ON‐OFF switch). DFT computational studies show that intramolecular charge transfer (ICT) phenomena occurs for both molecules, and reveal that protonation enhances the electron‐withdrawing ability of the triazine core and reduces the band gap. This acidochromic behavior was applied to a prototype fluorescent anti‐counterfeiting device. They also specifically recognize Fe3+ through coordination, and the recognition mechanism is closely related to the photoinduced electron transfer between Fe3+ and BPTT10/CPTT10. CPTTn self‐assemble into columnar rectangular (Colrec) mesophase, which can be modulated by oleic acid via the formation of a hydrogen‐bonded supramolecular liquid crystal hexagonal Colhex mesophase. Finally, CPTTn also form organic gels in alkanes at low critical gel concentration (3.0 mg/mL). Therefore, these star‐shaped triazine molecules possess many interesting features and thus hold great promises for information processing, liquid crystal semiconductors and organogelators.

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The Influence of Positional Isomerism of Terminal Alkyl Chains on Mesomorphic and Photophysical Behavior of Unsymmetric α-cyanostilbene-based Tetracatenars

Gao,

Liang,

Liu

et al. 2023

J Fluoresc

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Synthesis, LC self-assembly and photophysical behavior of stimuli responsive cyanostilbene-based hexacatenar mesogens with multicolour switching

Cited by 9 publications

References 47 publications

Dual-State Fluorescence in Some Salicylaldehyde-triphenylene Discotic Liquid Crystal Derivatives Induced by Excited State Intramolecular Proton Transfer

Dual-State Fluorescence in Some Salicylaldehyde-triphenylene Discotic Liquid Crystal Derivatives Induced by Excited State Intramolecular Proton Transfer

Phenanthrothiophene‐Triazine Star‐Shaped Discotic Liquid Crystals: Synthesis, Self‐Assembly, and Stimuli‐Responsive Fluorescence Properties

The Influence of Positional Isomerism of Terminal Alkyl Chains on Mesomorphic and Photophysical Behavior of Unsymmetric α-cyanostilbene-based Tetracatenars

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