Pyrene-cored blue-light emitting [4]helicenes: synthesis, crystal structures, and photophysical properties

Hu, Jian Yong; Paudel, Arjun; Seto, Nobuyuki; Feng, Xing; Era, Masanao; Matsumoto, Taisuke; Tanaka, Junji; Elsegood, Mark R. J.; Redshaw, Carl; Yamato, Takehiko

doi:10.1039/c3ob27320b

Cited by 47 publications

(26 citation statements)

References 70 publications

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“…Noteworthy, the trend in calculated band gap ( E gap theo ) variation over the series is closely similar to the one obtained from optical measurements ( E gap opt ). Finally, the helicene hybrid 3 appears to provide a better delocalisation in the π system that stabilises the HOMO level more than in the helicene hybrid 1 (−5.24 vs. −5.10 eV, respectively) 30…”

Section: Resultsmentioning

confidence: 93%

“…Finally, the helicene hybrid 3 appears to provide a better delocalisation in the p system that stabilises the HOMO level more than in the helicene hybrid 1 (À5.24 vs. À5.10 eV, respectively). [30] [b] The optical band gap was estimated from the intersection between the absorption and emission bands. [c] Quantum yields were calculated relative to [5]helicene in degassed dichloromethane (F = 0.04).…”

Section: Wwwchemeurjorgmentioning

confidence: 99%

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Synthesis, Crystal Structure and Photophysical Properties of Pyrene–Helicene Hybrids

Bédard

Vlassova

Hernandez‐Perez

et al. 2013

Chemistry A European J

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Synthesis of helically chiral aromatics resulting from fusion of pyrene and [4]- or [5]helicene has been accomplished using photoredox catalysis employing a Cu-based sensitizer as the key step. Photocyclisation experiments for the synthesis of the target compounds were carried out in batch and using continuous flow strategies. The solid-state structures, UV/Vis absorption spectra and fluorescence spectra of the pyrene-helicene hybrids were investigated and compared to that of the parent [5]helicene to discern the effects of merging a pyrene moiety within a helicene skeleton. The studies demonstrated that pyrene-helicene hybrids adopt co-planar or stacked arrangements in the solid state, in contrast to the solid-state structure of the parent [5]helicene. The UV/Vis and fluorescence spectra of the pyrene-helicene hybrids exhibited strong red-shifts when compared to the parent [5]helicene. DFT calculations suggest that the strategy of extending the π surface in the y axis of the helicenes increased their HOMO levels while also decreasing their LUMO levels, resulting in significantly reduced band gaps.

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Section: Resultsmentioning

confidence: 93%

Section: Wwwchemeurjorgmentioning

confidence: 99%

Synthesis, Crystal Structure and Photophysical Properties of Pyrene–Helicene Hybrids

Bédard

Vlassova

Hernandez‐Perez

et al. 2013

Chemistry A European J

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“…[32] Similarly,( E)-24 can be functionalized to the corresponding [4]helicenes 30 in good yields by intramolecular photocyclization. In particular,w eh ave synthesized novel types of pyrenecored blue-light-emitting [4]helicenes by means of intramolecular photocyclizations in the presence of iodine (as oxidant) in good yields.…”

Section: Cyclization Reactionf or Substituted Pyrene Derivativesmentioning

confidence: 99%

Functionalization of Pyrene To Prepare Luminescent Materials—Typical Examples of Synthetic Methodology

Feng

Redshaw

et al. 2016

Chemistry A European J

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144

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Pyrene-based π-conjugated materials are considered to be an ideal organic electro-luminescence material for application in semiconductor devices, such as organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs) and organic photovoltaics (OPVs), and so forth. However, the great drawback of employing pyrene as an organic luminescence material is the formation of excimer emission, which quenches the efficiency at high concentration or in the solid-state. Thus, in order to obtain highly efficient optical devices, scientists have devoted much effort to tuning the structure of pyrene derivatives in order to realize exploitable properties by employing two strategies, 1) introducing a variety of moieties at the pyrene core, and 2) exploring effective and convenient synthetic strategies to functionalize the pyrene core. Over the past decades, our group has mainly focused on synthetic methodologies for functionalization of the pyrene core; we have found that formylation/acetylation or bromination of pyrene can selectly lead to functionalization at K-region by Lewis acid catalysis. Herein, this Minireview highlights the direct synthetic approaches (such as formylation, bromination, oxidation, and de-tert-butylation reactions, etc.) to functionalize the pyrene in order to advance research on luminescent materials for organic electronic applications. Further, this article demonstrates that the future direction of pyrene chemistry is asymmetric functionalization of pyrene for organic semiconductor applications and highlights some of the classical asymmetric pyrenes, as well as the latest breakthroughs. In addition, the photophysical properties of pyrene-based molecules are briefly reviewed. To give a current overview of the development of pyrene chemistry, the review selectively covers some of the latest reports and concepts from the period covering late 2011 to the present day.

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“…However,the product yield can be much improved( to 70 %) by prolonging the reaction time and adding large amountso fi odine and propyleneo xide. [32] Similarly,( E)-24 can be functionalized to the corresponding [4]helicenes 30 in good yields by intramolecular photocyclization. [33] This approach opened the door to the preparation of more attractive pyrene-based extended p-conjugation PAHs.…”

Section: Cyclization Reactionf or Substituted Pyrene Derivativesmentioning

confidence: 99%

ChemInform Abstract: Functionalization of Pyrene to Prepare Luminescent Materials — Typical Examples of Synthetic Methodology

Feng

Redshaw

et al. 2016

ChemInform

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Pyrene-cored blue-light emitting [4]helicenes: synthesis, crystal structures, and photophysical properties

Cited by 47 publications

References 70 publications

Synthesis, Crystal Structure and Photophysical Properties of Pyrene–Helicene Hybrids

Synthesis, Crystal Structure and Photophysical Properties of Pyrene–Helicene Hybrids

Functionalization of Pyrene To Prepare Luminescent Materials—Typical Examples of Synthetic Methodology

ChemInform Abstract: Functionalization of Pyrene to Prepare Luminescent Materials — Typical Examples of Synthetic Methodology

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