Electrophilic Aromatic Substitution of 7-f-butyl-1,3-dimethylpyrene: Preparation of 5-mono- and 5,9-di-substituted 7-f-butyl-1,3-dimethylpyrenes

Chemistry An Asian Journal

Liu

et al. 2012

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A series of pyrene-based Y-shaped blue emitters, namely, 7-tert-butyl-1,3-diarylpyrenes 4 were synthesized by the Suzuki cross-coupling reaction of 7-tert-butyl-1,3-dibromopyrene with a variety of p-substituted phenylboronic acids in good to excellent yields. These compounds were fully characterized by X-ray crystallography, UV/Vis absorption and fluorescence spectroscopy, DFT calculations, thermogravimetric analysis, and differential scanning calorimetry. Single-crystal X-ray analysis revealed that the Y-shaped arylpyrenes exhibited a low degree of π stacking owing to the steric effect of the bulky tert-butyl group in the pyrene ring at the 7-position, and thus, the intermolecular π-π interactions were effectively suppressed in the solid state. Despite the significantly twisted nonplanar structures, these molecules still displayed efficient intramolecular charge-transfer emissions with clear solvatochromic shifts on increasing solvent polarity. An intriguing fact is that all of these molecules show highly blue emissions with excellent quantum yields in the solid state. Additionally, the two compounds containing the strongest electron-accepting groups, CN (4 d) and CHO (4 f), possess high thermal stability, which, together with their excellent solid-state fluorescence efficiency, makes them promising potential blue emitters in organic light-emitting device applications.

Section: Resultsmentioning

confidence: 99%

Pyrene‐Based Y‐shaped Solid‐State Blue Emitters: Synthesis, Characterization, and Photoluminescence

Chemistry An Asian Journal

Liu

et al. 2012

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“…Additionally, in our laboratory, we also reported the selective formation of the 5-mono-and 5,9-di-substitution products from 7-tert-butyl-1,3-dimethylpyrene by formylation and acetylation depending on the type of Lewis acid catalyst deployed. 12 More recently, the 1-and 3-positions of pyrene were brominated using 2-tert-butylpyrene; the tert-butyl group on the pyrene ring protects the ring from electrophilic attack at the 6,8-positions. applications.…”

mentioning

confidence: 99%

Blue-Emitting Butterfly-Shaped 1,3,5,9-Tetraarylpyrenes: Synthesis, Crystal Structures, and Photophysical Properties

Iwanaga

et al. 2013

Org. Lett.

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“…As showni nS cheme10, Kime ta l [40] showed that N,N-dimethylaniline and1 -(trifluoromethyl)benzene groups arer andomlyattachedatthe 1-,3 -, 6-,a nd 8-positionso fp yrenet hrough as tepwiseS onogashira coupling. [41] These results seem to indicatet hat the solvent and initiator used play as ignificant role in this bromination process. Thea bove examples inspired us to developanovels tereocontrolled method for thef unctionalization of pyrene in ordert oa ccessh igh-performance electroluminescencematerials.…”

Section: Bromination Of Pyrene 31 Regioselective Bromination Of Pyrenementioning

confidence: 80%

“…In addition, in the absence of initiator, bromination of compound 6 with NBS in carbon tetrachloride resulted in compounds 40 in 83 % yield and 41 in only 8 % yield. Similarly, in benzene, bromopyrene 41 was obtained in only 7 % yield along with recovered starting material (Scheme ) . These results seem to indicate that the solvent and initiator used play a significant role in this bromination process.…”

Section: Bromination Of Pyrenementioning

confidence: 91%

“…Similar results were observed for aceylation, for example, mixing 6 with acetyl chloride in the presence of TiCl 4 afforded 5‐acetyl‐7 ‐tert‐ butyl‐1,3‐dimethylpyrene ( 21 b ) in 85 % yield. By contrast, use of AlCl 3 as catalyst resulted in 5,9‐diacetyl‐7‐ tert ‐butyl‐1,3‐dimethyl pyrene ( 22 b ) in 95 % yield (Scheme ) . It is possible here that the activity of the entire framework has been reduced when the 4‐position is occupied by an electron‐withdrawing group.…”

Section: Formylation/acetylation Of Pyrenementioning

confidence: 99%

See 1 more Smart Citation

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

Redshaw

et al. 2016

Chemistry A European J

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219

144

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.