“…The HI-catalyzed reductive aromatization of peri aryl-substituted pentacenediol 2 involves the formation of asym -TPP 3 followed by the spontaneous generation of an isomeric, ring-fused anthracene derivative 3a , which is derived from the acid-catalyzed rearrangement of asym -TPP 3 (Scheme ). Similar rearrangement byproducts were isolated during the syntheses of 1,4,9,10-tetraphenylanthracene and rubrene. , DMPDPP 5 was much more stable than asym -TPP 3 toward the acid-catalyzed rearrangement because the sterically hindered xylyl groups effectively interfered with the cyclization of the adjacent cation. 2 Proposed Acid-Catalyzed Rearrangement of a sym -TPP …”
Two aryl-substituted red emitting pentacenes, 5,6,13,14-tetraphenylpentacene (asym-TPP) and 5,14bis(2,6-dimethylphenyl)-6,13-diphenylpentacene (DMPDPP), have been prepared and spectroscopically characterized. Guest-host films of pentacene derivatives dispersed in tris(quinolin-8-olato)aluminum(III) (Alq 3 ) exhibit narrow red emission (λ max ) 663-680 nm), indicative of efficient Fo ¨rster energy transfer from the Alq 3 host to the guest molecules. Solid-state absolute photoluminescence quantum yields of the films were measured as a function of guest molecule concentration (Φ PL ∼20% at 0.20-0.50 mol %). Red light-emitting diodes based on the fluorescent DMPDPP yield external electroluminescence quantum efficiency (η EL ∼1%) close to the theoretical limit.
“…The HI-catalyzed reductive aromatization of peri aryl-substituted pentacenediol 2 involves the formation of asym -TPP 3 followed by the spontaneous generation of an isomeric, ring-fused anthracene derivative 3a , which is derived from the acid-catalyzed rearrangement of asym -TPP 3 (Scheme ). Similar rearrangement byproducts were isolated during the syntheses of 1,4,9,10-tetraphenylanthracene and rubrene. , DMPDPP 5 was much more stable than asym -TPP 3 toward the acid-catalyzed rearrangement because the sterically hindered xylyl groups effectively interfered with the cyclization of the adjacent cation. 2 Proposed Acid-Catalyzed Rearrangement of a sym -TPP …”
Two aryl-substituted red emitting pentacenes, 5,6,13,14-tetraphenylpentacene (asym-TPP) and 5,14bis(2,6-dimethylphenyl)-6,13-diphenylpentacene (DMPDPP), have been prepared and spectroscopically characterized. Guest-host films of pentacene derivatives dispersed in tris(quinolin-8-olato)aluminum(III) (Alq 3 ) exhibit narrow red emission (λ max ) 663-680 nm), indicative of efficient Fo ¨rster energy transfer from the Alq 3 host to the guest molecules. Solid-state absolute photoluminescence quantum yields of the films were measured as a function of guest molecule concentration (Φ PL ∼20% at 0.20-0.50 mol %). Red light-emitting diodes based on the fluorescent DMPDPP yield external electroluminescence quantum efficiency (η EL ∼1%) close to the theoretical limit.
“…In comparison, [2.2]paracyclophane has its aromatic protons at 3.63,28 0.68 ppm higher than pxylene.29 Shifts of 0.5-0.6 ppm have also been noted with the phenylated naphthalenes9•30 and anthracenes. 10 The chloro derivative V also had two aromatic multiplets (centering at 2.90 and 3.30), a singlet at 5.42 assignable to the benzohydrylic protons vicinal to the carbon nearest the chlorine atom, a doublet at 5.73 (J = 2.8 cps) assignable to the other benzohydrylic protons, and a triplet at 7.03 assignable to the 11a proton.…”
“…It is quite evident that if as uitable quinone precursor is available, it is af ar superior approach, as demonstrated by the relatively facile syntheses of the previously reported compounds 1, 2,a nd 14,t he overall yields of which increased by 50-, 24-, and 66-fold, respectively.P rofessor Pascal, to whom we have communicated our preliminary synthetic results, reports that afirst-year graduate studentw as able to prepare five grams of pentacene 2 in less than two weeks by using our method,w hich also speaks for its scalability.A M1 calculations provide ag ood guide for the end-to-end twistso fL TAs, but cannot predict how the twists will be impacted by crystal packing forces as compounds 10 (134.68 versus AM1 141.58), 11 (147.78 versus AM1 144. 18), and 12 demonstrate (140.98 versusA M1 1448). And counter to what one would think, addition of bulkiera ryllithium substituents-asc ompared to the phenyl group-has little to no impact on the end-to-end twist as predicted by AM1 and confirmedb yX -ray crystallography, although each differs slightly from calculations in their solid state (Table 1).…”
Section: Discussionmentioning
confidence: 90%
“…Interestingly,i th as been applied to the syntheses of several sterically congested anthracenes. [16][17][18][19] Intrigued,w ea dded phenyllithium to ar efluxing suspension of octaphenylanthraquinone [20] (4)i nd ry benzene. The diol intermediate, whichw as isolated from the reaction mixture but not purified, was treatedw ith SnCl 2 and HCl in refluxingT HF to form 1 in 52 %y ield, a5 0-foldi mprovement over its original synthesis (Scheme 1).…”
Seven longitudinally twisted acenes (an anthracene, two tetracenes,t hree pentacenes, and ah exacene) have been synthesizedb yt he addition of aryllithium reagents to the appropriate quinone precursors, followed by SnCl 2 -mediatedr eductiono ft heir diol intermediates, and severalo ft hese acenesh ave been crystallographicallyc haracterized. The new syntheses of the three previously reported twisted acenes, decaphenylanthracene (1), 9,10,11,20,21,22-hexaphenyltetrabenzo[a,c,l,n]pentacene( 2), and 9, 10,11,12,13,14,15,16-octaphenyldibenzo[a,c]tetracene (14), resulted in ar eductiono ft he number of synthetic steps.A saconsequence their overall yields werei ncreased by factors of 50-, 24-, and 66-fold, respectively.A ll of the twisted acenes yntheses reported here are suitable fort he synthesis of at least gram quantities of these remarkable hydrocarbon materials.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
