Star-shaped Triphenylene-triazine Multi-stimuli Responsive Discotic Liquid Crystals: Synthesis, Properties and Applications

Chongyang, Zeng; Hu, Ping; Wang, Bi‐Qin; Fang, Wenyan; Zhao, Ke‐Qing; Donnio, Bertrand

doi:10.6023/a23010006

Cited by 4 publications

(4 citation statements)

References 57 publications

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“…It can be seen that ESIPT nonradiative relaxation fraction weakens the LE and PE of the LEDs. Moreover, this LE and PE level has been slightly improved compared to similar triphenylene LED devices reported recently. , …”

Section: Resultssupporting

confidence: 50%

“…Liquid-crystalline triphenylenes , and structurally related derivatives − are very popular in this field, not only because of their one-dimensional, high rate charge carrier migration, which is of interest for most photophysical applications, but also for the versatility of their synthesis and the many possible chemical and structural modifications still compatible with the emergence of columnar mesomorphism. Most of the ESIPT liquid crystal molecules reported at this stage have dealt with the effect of ESIPT-induced isomerization on optical properties, but whether this isomerization will affect the liquid crystal behavior seems to be inconclusive.…”

Section: Resultsmentioning

confidence: 99%

“…All three types of compounds were synthesized from accessible key-compound TP n - Br (Scheme ). − Triphenylene derivatives TP n - SA ( n = 4, 6, 12) and TP n - S ( n = 4, 6, 12) were efficiently obtained by Suzuki–Miyaura reaction with 2-hydroxy-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzaldehyde and 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzaldehyde, respectively (Scheme ), whereas TPS 6, with the fused ring triphenylene-aldehyde derivative, was prepared by the Bouveault aldehyde synthesis (TP-Li and DMF). Yields of TP n - SA and TP n - S can reach about 75% but only around 50% for TPS 6, likely due to traces of water still present in DMF.…”

Section: Resultsmentioning

confidence: 99%

“…Compared with inorganic LEDs, the compounds preparation conditions are thus milder, the raw materials are cheaper, and even the photon absorption can be overcome. , For the photoelectric properties, since their luminescence comes from the excitation of blue chips, the turn-on voltages are low . Due to the good QY in solid state, they can maintain relatively high LE and PE in the same level of triphenylene-based LEDs ( TPPT 6, 7.41 lm/W; CTpCN , 2.02 lm/W; etc.) and even exceed that of some small luminescent molecules reported recently ( TSH , 4.39 lm/W) .…”

Section: Resultsmentioning

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: Resultssupporting

confidence: 50%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

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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Mesomorphism Modulation of Perfluorinated Janus Triphenylenes by Inhomogeneous Chain Substitution Patterns

Zhang,

Yu,

Zhao

et al. 2024

Chemistry An Asian Journal

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Two isomeric series of compounds with “inverted” chains’ substitution patterns, 7,10‐dialkoxy‐1,2,3,4‐tetrafluoro‐6,11‐dimethoxytriphenylene and 6,11‐dialkoxy‐1,2,3,4‐tetrafluoro‐7,10‐dimethoxytriphenylene, labelled respectively p‐TPFn and m‐TPFn, and two non‐fluorinated homologous isomers, 3,6‐dibutoxy‐2,7‐dimethoxytriphenylene and 2,7‐dibutoxy‐3,6‐dimethoxytriphenylene, p‐TP4 and m‐TP4, respectively, were synthesized in three steps and obtained in good yields by the efficient transition‐metal‐free, fluoroarene nucleophilic substitution via the reaction of appropriate 2,2’‐dilithium biphenylenes with either perfluorobenzene, C6F6, to yield p‐TPFn and m‐TPFn, or o‐difluorobenzene, C6H4F2, for p‐TP4 and m‐TP4, respectively. The single‐crystal structures of p‐TPF4, m‐TPF4 and p‐TP4, unequivocally confirmed that the cyclization reactions occurred at the expected positions, and that the fluorinated molecules stack up into columns with short separation, a propitious situation for the emergence of columnar mesophases. The mesomorphous properties were found to be greatly affected by both chains’ length and positional isomerism: a Colhex phase is found for p‐TPF4 and m‐TPF4, but mesomorphism vanishes in p‐TPF6, and changes for the isomeric homologs m‐TPFn, with the induction for n ≥ 6 of a lamello‐columnar phase, LamColrec. As expected, both non‐fluorinated compounds are deprived of mesomorphism. These compounds emit blue‐violet colour in solution, independently of the chain ‘substitution pattern, and the absolute fluorescence quantum yields can reach up to 46%. In thin films, fluorescence is slightly redshifted.

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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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Star-shaped Triphenylene-triazine Multi-stimuli Responsive Discotic Liquid Crystals: Synthesis, Properties and Applications

Cited by 4 publications

References 57 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

Mesomorphism Modulation of Perfluorinated Janus Triphenylenes by Inhomogeneous Chain Substitution Patterns

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

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