Synthesis, electrochemical, thermal and photophysical characterization of photoactive discotic dyes based on the tris-[1,2,4]-triazolo-[1,3,5]-triazine core

Dal-Bó, Alexandre Gonçalves; Cisneros, Georgina Gisel López; Cercená, Rodrigo; Mendes, Jackson; Silveira, Letícia Matos da; Zapp, Eduardo; Domiciano, Kelvin Guessi; Duarte, Rodrigo da Costa; Rodembusch, Fabiano Severo; Frizon, Tiago Elias Allievi

doi:10.1016/j.dyepig.2016.06.041

Cited by 12 publications

(20 citation statements)

References 25 publications

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“…Tartakovsky observed a mixture of isomeric TTTs 53, 55 when 14 (R = phenyl) was heated to 350°C. Onset for decomposition of the p-hexyloxyphenyl TTT 20 is 445°C, [23] only TTT 36 with benzyloxy side chains partly decomposed above its clearing point (264°C), but this was attributed to an easy debenzylation, occurring at 315°C (TGA). Gallardo [7,21] and we [8,22] observed broad mesophases, some with clearing points above 200°C; TGA measurements demonstrated a thermal stability up to 400°C!…”

Section: Synthesismentioning

confidence: 99%

“…tris-decyl t-TTT 15 has a maximum at λ max = 244 nm, slightly shifting bathochromic with increasing concentration and solvent polarity. [7,18,23] In highly polar solvents, increasing length of alkyl chains results in dramatic decrease of the molar absorptivity, e.g. [6] The UV absorption of p-alkoxyphenyl t-TTTs 16-21 has a maximum at λ max = 290 nm and shows a weak negative solvatochromism.…”

Section: Optical Propertiesmentioning

confidence: 99%

“…The weak fluorescence of this compound peaks at λ F max = 307 nm and is quenched by trifluoroacetic acid. [23] According to INDO/S-CIS calculations, the main band at 290 nm involves a HOMO-LUMO and a HOMO-LUMO+1 transition (calculated: 295 nm). [7,18,23] In highly polar solvents, increasing length of alkyl chains results in dramatic decrease of the molar absorptivity, e.g.…”

Section: Optical Propertiesmentioning

confidence: 99%

“…[7,18,23] In highly polar solvents, increasing length of alkyl chains results in dramatic decrease of the molar absorptivity, e.g. [23] The absorption and emission maxima of triphenyl t-TTTs are redshifted with increasing donor strength in the sequence 3,5-dialkoxy < 4-alkoxy <3,4-dialkoxy < 4-dialkylamino (e.g.25 < 20 < 29 < 23). [23] According to INDO/S-CIS calculations, the main band at 290 nm involves a HOMO-LUMO and a HOMO-LUMO+1 transition (calculated: 295 nm).…”

Section: Optical Propertiesmentioning

confidence: 99%

“…[7] The emission of 16-21 in chloroform peaks at λ max = 362 nm. Solid state UV spectra show a clear dependence of the absorptivity on the red side of the spectra from the p-alkoxy chain length (methyl -dodecyl): increasing length shifts the absorption maxima [7] and band edge [23] to higher energies, suggesting the formation of aggregates in the ground state probably via π-stacking of the heteroaromatic units. Typical radiative lifetimes are in the range of 0.8-1 ns.…”

Section: Optical Propertiesmentioning

confidence: 99%

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Tristriazolotriazines: Luminescent Discotic Liquid Crystals

Detert

2018

Eur J Org Chem

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Tristriazolotriazines (TTT) are new tetracyclic and planar cores for discotic liquid crystals. Two symmetrical isomers are known, paddle‐wheel type t‐TTTs and r‐TTTs with the shape of a propeller. Cyclocondensation of chlorotriazoles gives r‐TTTs, Huisgen reaction of tetrazoles and cyanuric chloride yields t‐TTTs with tangentially attached substituents. Many alkoxyphenyl‐substituted t‐TTTs form broad mesophases, typically with a hexagonal columnar structure. These luminescent molecules, when heated above 200 °C, suffer a thermal isomerization. A threefold ring opening/ring closing mechanism transforms t‐TTTs via unsymmetrical isomers to r‐TTTs. Thermotropic properties are largely influenced by planarization and increase of molecular diameter. Increased melting points, even the complete loss of liquid crystallinity have been observed, but also the gain of mesomorphism.

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Section: Synthesismentioning

confidence: 99%

Section: Optical Propertiesmentioning

confidence: 99%

Section: Optical Propertiesmentioning

confidence: 99%

Section: Optical Propertiesmentioning

confidence: 99%

Section: Optical Propertiesmentioning

confidence: 99%

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Tristriazolotriazines: Luminescent Discotic Liquid Crystals

Detert

2018

Eur J Org Chem

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Reaching Room‐Temperature Mesomorphism through Expansion of the Tristriazolotriazine Core with Alkoxybenzoate Units

et al. 2022

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The tristriazolotriazine (TTT) N‐heterocycle, despite being a relatively new mesogenic core for use in discotic liquid crystals, has already demonstrated its importance and promising characteristics. In this work, we extended the knowledge about the TTT, increasing the core size with alkoxybenzoate units, as well as evaluating how the expansion and number of peripheral chains affected the thermal and photophysical properties, both in solution and spin‐coated films. Their thermal behaviour and self‐assembly were studied by differential scanning calorimetry, polarizing optical microscopy and X‐ray diffraction with synchrotron radiation, while the photophysics was investigated by UV‐Vis absorption and fluorescence spectroscopy. The results show that, despite a considerable decrease in the fluorescence quantum yield with the core expansion, the mesomorphic properties are significantly enhanced, with two products showing Colh mesophase at room temperature, with large range of mesomorphism and very good thermal stability. It was also demonstrated how structural changes affected the self‐assembly properties.

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Experimental and theoretical investigation on the thermal isomerization reaction of tristriazolotriazines

Jochem

Limbach

Glang

et al. 2022

J of Physical Organic Chem

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The isomerization of tristriazolotriazione with tangential substituents to radial isomers occurs in a cascade of three ring opening/rotation/ring closure steps of the central triazine. Donor substitution accelerates the isomerization which can be catalyzed by Brønsted acids. The velocity of the rearrangements drops with each step by a factor of 4, whereas the gain in heat of formation increases. Density functional theory (DFT) calculations led to transition states; their energies correspond to the experimental data. Threefold isomerization strongly affects the mesomorphic properties.

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Synthesis, electrochemical, thermal and photophysical characterization of photoactive discotic dyes based on the tris-[1,2,4]-triazolo-[1,3,5]-triazine core

Cited by 12 publications

References 25 publications

Tristriazolotriazines: Luminescent Discotic Liquid Crystals

Tristriazolotriazines: Luminescent Discotic Liquid Crystals

Reaching Room‐Temperature Mesomorphism through Expansion of the Tristriazolotriazine Core with Alkoxybenzoate Units

Experimental and theoretical investigation on the thermal isomerization reaction of tristriazolotriazines

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