New benzenogenic diene syntheses

Clar, E.; Lovat, M.M.; Simpson, W. Irven

doi:10.1016/s0040-4020(01)97503-9

Cited by 8 publications

(2 citation statements)

References 7 publications

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“…220 °C; [19–21] 3 : ca . 138 °C [20] ( Table 1). The introduction of a symmetric 3′,5′‐dialkoxyphenyl group ( 1a – 3a ) does not change the symmetry of the derivative.…”

Section: Resultsmentioning

confidence: 99%

Room‐Temperature Alkyl‐Diphenylpyrene Liquefication by Molecular Desymmetrization

Shinohara

Kawamura

et al. 2023

Helvetica Chimica Acta

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Achieving the lowest phase transition temperature with minimal chemical modification in highly crystalline π‐conjugated molecules is a universal problem in related research fields. This paper reports room‐temperature liquefication of diphenylpyrene isomers by introducing bulky yet flexible branched alkyl chains through molecular desymmetrization. Six isomers with different symmetries depending on the positions of the phenyl groups and alkyl groups were synthesized, and three of the isomers were found to be liquids at 25 °C, a state in which they have remained for more than five years. Although it is generally believed that the lower the symmetry of a molecule, the less likely it is to crystallize, one molecule with a relatively high molecular symmetry unexpectedly did not crystallize, which was evidenced by the kinetic inhomogeneity of this amorphous material (practically stable liquid) assessed by rheological analysis.

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“…220 °C; [19–21] 3 : ca . 138 °C [20] ( Table 1). The introduction of a symmetric 3′,5′‐dialkoxyphenyl group ( 1a – 3a ) does not change the symmetry of the derivative.…”

Section: Resultsmentioning

confidence: 99%

Room‐Temperature Alkyl‐Diphenylpyrene Liquefication by Molecular Desymmetrization

Shinohara

Kawamura

et al. 2023

Helvetica Chimica Acta

View full text Add to dashboard Cite

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“…Structurally speaking graphene belongs to the polycyclic aromatic hydrocarbon class of molecules (PAHs), [94][95][96][97][98][99][100][101][102][103][104][105][106][107][108] and thus in principle it is possible to synthesize graphene-like smaller PAHs with solution-chemistry routes. The major advantages of the solution-chemistry approach are that the resultant graphenes are well-defined and identical, and that they can be produced in large quantities.…”

mentioning

confidence: 99%

Solution-chemistry approach to graphene nanostructures

Yan

2011

J. Mater. Chem.

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Graphene has many novel optical and electrical properties desirable for applications in future electrooptical devices. Graphene nanostructures are especially attractive for their wide range of tunable properties. Here we describe the recent progress and challenges in the solution-chemistry approach to graphene nanostructures. This approach could not only lead to new materials with various well-defined properties, but also enable their production in large quantities.Graphene, containing a single layer of sp 2 -hybridized carbon atoms, has become an intensively studied topic because of its unique two-dimensional (2D) crystalline structure, extraordinary physical properties, 1-3 and potential applications in future optics and electronics. Even though graphene is the basic building block for graphite, carbon nanotubes, and fullerenes which have been studied for decades, not a lot of attention was paid to graphene until the first isolation of single-layer graphene from graphite by Geim and his co-workers 4 with a ''Scotch tape'' approach in 2004. Numerous follow-up investigations subsequently revealed a wide range of very attractive properties, such as extremely high carrier mobilities, 5-9 quantum hall effect, 10-16 and ambipolar field effect, 4,17 etc. These properties make graphene a very promising material for future devices, such as high-speed, high-frequency electronic devices, 6,7,18-21 single molecule sensors, 22,23 and ultrathin transparent electrodes. [24][25][26][27][28][29][30][31] Reliable production of graphene with high quality and in large quantities is still a challenge. 32 Although some proof-of-concept devices have been made from mechanically exfoliated graphene, the original layer-by-layer peel-off method cannot be used for large-scale production. In order to overcome this challenge, two distinct approaches have been taken by scientists: breaking down graphite into graphene (''top-down'' approach) and building up graphene from atomic or molecular building blocks (''bottom-up'' approach). The top-down approaches include mechanical exfoliation, 1,4,18 intercalation followed by solution-based exfoliation, 28,30,33-45 reduction of graphene oxide, 46-56 etc, (Fig. 1). The bottom-up approaches mostly include chemical vapor deposition (CVD) 31,57-66 and a solution-chemistry approach. 67,68 In this review we discuss the latest development in the emerging solution-chemistry approach to graphene nanostructures, especially quantum dots (QDs). 69 We refer readers to some recent reviews 70-72 for detailed descriptions of top-down approaches and CVD methods to make graphene.To make stable single-layer graphene it is essential to overcome inter-layer van der Waals attraction that favors formation of graphite. It is achieved in mechanical exfoliation with external forces, and in CVD methods with introduction of substrates to simultaneously immobilize graphene when they form.

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