The Synthesis of Pyracene<sup>1</sup>

Anderson, Albert G.; Wade, Robert H.

doi:10.1021/ja01129a032

Cited by 21 publications

(9 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The chemistry used to develop those materials has originated from the very convenient 1,2-diketone/phenylene-1,2-diamine double dehydration reaction leading to pyrazines, which not only gives excellent yields of polycyclic fused acenes but also leads to an incorporation of electron deficient pyrazine units whose presence reduces the propensity for the oxidation of the relevant molecules and allows the preparation of some very impressive aromatic molecular species such as N-heteroacenes, which are sometimes termed pyrazaacenes (Figure ) but are not to be confused with the pyracenes (Figure ). Other reactions have also been exploited for the incorporation of fused pyrazine units including double Buchwald-Hartwig Pd-catalyzed coupling and simple aromatic nucleophilic substitution reactions, which can be facilitated when substitution is performed on already electron-deficient heterocycles. In fact, N-heteroacenes , or azaacenes can be considered “part-carbon” pyrazinacenes , representing an important stepping stone on the way to establishing the pyrazinacene concept.…”

Section: Introductionmentioning

confidence: 99%

The Pyrazinacenes

Richards

Hill

2021

Acc. Chem. Res.

View full text Add to dashboard Cite

Conspectus Pyrazinacenes are a class of nitrogen-containing heteroacene molecules composed of linearly fused pyrazine units, which might also include dihydropyrazine groups leading to different reduced states of the compounds. While they are structurally similar to hydrocarbon acenes (e.g., pentacene) the presence of increasing numbers of N-heteroatoms introduces several different additional features of the compounds so that they can be considered for investigations beyond those suggested for acenes (i.e., organic field-effect transistors, solar cell components). Pyrazinacenes are in several ways complementary to C–H-only acenes based on the increasing stability of reduced states of the compounds with increasing numbers of fused pyrazine rings, although an acene-like electronic structure persists in the compounds so far studied. However, the introduction of multiple N atoms leads to properties that depart from C–H-only acenes. In particular, the compounds exhibit a delocalization of NH protons in extended reduced compounds and oxidation state switchability in solution and at interfaces. The presence of NH groups also allows an easy introduction of solubilizing groups at the pyrazinacene chromophore. In this Account, we will describe the preparation of extended pyrazinacenes from dipyrazino[2,3-b:2′,3′-e]pyrazine (1,4,5,8,9,10-hexaazaanthracene; N6) derivatives up to 1,4,5,6,7,8,9,12,13,14,15,16,17,18-tetradecaazaheptacene (N14) and also assess structures of the relevant compounds based on X-ray crystallographic studies. Emergent properties of the molecules include highly unusual linear tautomeric processes based on a delocalization of protons (and the corresponding formation of orbitals based on multiple adjacent N lone electron pair interactions), which suggest special transport properties based on molecular protonics. Molecules such as decazapentacene (N10) exhibit multistability of oxidation state, and this is predicted to promote the redox catalytic properties of the compounds. The oxidation-state switching of on-surface processes is also described and has been investigated using scanning tunneling microscopy. The longest known pyrazinacene chromophore (N14) exhibits amphiprotism with its state of protonation being strongly coupled to its fluorescence emission properties in the near-infrared region indicating possible uses in pH-coupled bioimaging applications. The synthesis of the pyrazinacenes is flexible and allows the preparation of symmetrically or unsymmetrically substituted derivatives for the development of more complex molecules and for control of the electronic structure of the acene unit. Overall, the pyrazinacenes represent an emerging class of highly nitrogenous heteroacenes with unique properties and excellent potential for development in different applications based on their special supramolecular properties including guest binding or interactions in biological systems.

show abstract

Section: Introductionmentioning

confidence: 99%

The Pyrazinacenes

Richards

Hill

2021

Acc. Chem. Res.

View full text Add to dashboard Cite

show abstract

“…Because of this ambivalent character, many efforts have been undertaken to synthesize pyracylene, which turned out to be a difficult task. The first attempts, started as early as 1952 by Anderson et al., were not successful 15. 16 In the 1960s, Trost et al.…”

Section: Introductionmentioning

confidence: 99%

Model for the viscoelastic and viscoplastic responses of semicrystalline polymers

Drozdov

Christiansen

2003

J of Applied Polymer Sci

View full text Add to dashboard Cite

Constitutive equations are derived for the time-dependent behavior of semicrystalline polymers at isothermal loading with small strains. A semicrystalline polymer at temperatures above the glass-transition point for its amorphous phase is thought of as a network of macromolecules bridged by junctions (physical crosslinks, entanglements, and crystalline lamellae) that can slide with respect to their reference positions in the bulk material under straining. The network is assumed to be highly inhomogeneous, and it is modeled as an ensemble of mesoregions (MRs) with various strengths of interchain interaction. Two types of MRs are distinguished: passive, where these interactions prevent detachment of strands from junctions; and active, where active strands separate from junctions and dangling strands merge with the network at random times as they are thermally agitated. The viscoelastic response of a semicrystalline polymer reflects reformation of strands in active MRs, whereas its viscoplastic behavior is associated with sliding of junctions. Stress-strain relations for uniaxial deformation are developed by using the laws of thermodynamics. Adjustable parameters in the constitutive equations are found by fitting experimental data for isotactic polypropylene in a tensile test with a constant strain rate and in tensile relaxation tests at various strains. Fair agreement is demonstrated between the observations and the results of numerical simulation. It is revealed that the viscoplastic flow of junctions strongly affects the rearrangement process in active MRs, whose rate reaches a threshold value in the vicinity of the apparent yield point.

show abstract

“…The 254-nm photolysis of mesitylene in low-temperature matrices (77 K) produces 3,5-dimethylbenzyl monoradical and the mesitylylene (3-methyl-mxylylene) biradical whose fluorescence spectra originate around 487 and 452 nm, respectively. Since both species are always (1) Migirdicyan, E.; Baudet, J. J. Am.…”

Section: Resultsmentioning

confidence: 99%

The mechanism of formation of m-xylylene type biradicals produced by photolysis of polymethyl benzenes or dihalomethyl benzenes

Haider¹,

Migirdicyan²,

Platz³

et al. 1990

J. Am. Chem. Soc.

View full text Add to dashboard Cite

of reaction are CF3NF" and (CF3)2N~. CF2=N is consistently defeated as a nucleophile, but FCN can be used as an electrophilic substrate with a suitably nucleophilic anion. The list of ¡mines that have been successfully attacked by CF3NF~i ncludes the CF2=NX series (X = F, Cl, Br)4,18,29 and CF3N=CF2, but other qualified substrate ¡mines should behave similarly.Alkali metal fluoride promoted reactions of the other Ahalodifluoromethylenimines, CF2=NX (X = Cl, Br), offer little evidence of nucleophilic anions like CF3NF~. Neither the CF3NC1" anion near the CF3NBr" anion, both far less stable over the metal fluoride surface, have reacted nucleophilically with any of the substrates that we have examined.18In summary, the competitive reactions of the perfluorinated imines, CF2=NF and CF3N==CF2, and FCN in the presence of

show abstract

The Synthesis of Pyracene¹

Cited by 21 publications

References 0 publications

The Pyrazinacenes

The Pyrazinacenes

Model for the viscoelastic and viscoplastic responses of semicrystalline polymers

The mechanism of formation of m-xylylene type biradicals produced by photolysis of polymethyl benzenes or dihalomethyl benzenes

Contact Info

Product

Resources

About

The Synthesis of Pyracene1

Cited by 21 publications

References 0 publications

The Pyrazinacenes

The Pyrazinacenes

Model for the viscoelastic and viscoplastic responses of semicrystalline polymers

The mechanism of formation of m-xylylene type biradicals produced by photolysis of polymethyl benzenes or dihalomethyl benzenes

Contact Info

Product

Resources

About

The Synthesis of Pyracene¹