“…Parallel to the synthesis of poly(heteroarylenemethines) by various elimination routes (see section VI.B), Hanack et al have developed another approach based on the preparation of short chain conjugated precursors already containing the desired methine linkage. − These precursors have been synthesized by Knoevenagel type condensation of thiophene or pyrrole-2-carboxaldehyde with dihydrothiophene sulfones 59 (Scheme , route A) or with sulfoxides 60 , (route B) possibly substituted at the 3- and 4-positions. 18 …”
Section: Diheteroarylene Methinesmentioning
confidence: 99%
“…In the case of unsubstituted sulfones, reduction to the sulfide state ( 61 ) could not be achieved and the sulfoxide route was the preferred one . Whereas a large number of precursors have been synthesized, , only a few examples of the corresponding polymers have been briefly described. , …”
“…Parallel to the synthesis of poly(heteroarylenemethines) by various elimination routes (see section VI.B), Hanack et al have developed another approach based on the preparation of short chain conjugated precursors already containing the desired methine linkage. − These precursors have been synthesized by Knoevenagel type condensation of thiophene or pyrrole-2-carboxaldehyde with dihydrothiophene sulfones 59 (Scheme , route A) or with sulfoxides 60 , (route B) possibly substituted at the 3- and 4-positions. 18 …”
Section: Diheteroarylene Methinesmentioning
confidence: 99%
“…In the case of unsubstituted sulfones, reduction to the sulfide state ( 61 ) could not be achieved and the sulfoxide route was the preferred one . Whereas a large number of precursors have been synthesized, , only a few examples of the corresponding polymers have been briefly described. , …”
“…The mono- and disubstituted dithiophene ( 13 and 14 ) can be synthesized via selective lithiation. 14 The reactivity of 13 is identical to those of 9 and 11 . The low-temperature condition leads to the migratory product ( 13b ) in moderate yield, while the anthracene derivative ( 13a ) is produced in low yield at room temperature.…”
The structural diversity
of polycyclic aromatic hydrocarbons (PAHs)
offers exciting opportunities for their applications. Yet, selective
synthesis of such conjugated networks poses a formidable challenge.
Compared to the prominence of transition-metal-catalyzed cross-coupling
and oxidative Scholl reactions, cationic rearrangement in the synthesis
of polycyclic aromatic hydrocarbon is an underexplored subject. In
this study, we reveal that cationic intermediate generated from epoxy
dibenzocycloheptanol can be transformed into acenes, azulene-embedded
PAHs, and dibenzocycloheptanone derivatives. Reactive patterns, including
Meinwald rearrangement, Nazarov cyclization, transannular aryl migration,
and transannular Friedel–Crafts cyclization were identified.
Both substrate structures and reaction temperature affect the reaction
pathways in predictable and manageable manners. A mechanistic scheme
was postulated as the working model to guide the reactivity for further
application. Substrates containing heterocyclic and ferrocenyl groups
exhibit similar reactivity profiles. The inquiry culminates in the
selective synthesis of 5, 7, 12, 14-tetrasubstituted
C
2
h
and
C
2
v
pentacene derivatives. Our results demonstrate that
polycyclic aromatic hydrocarbons can be selectively prepared with
this cation-initiated strategy by methodically tuning the reactivity.
“…32 The general procedure of synthesizing methine-bridged polymers of PbEDOP-b and PbEDOP-nb were through acid-catalyzed polymerization reported previously by one of us. 15,16 Poly[(2,5-n-benzyl-3,4-ethylenedioxypyrrolediyl)benzylidene-(2,5-n-benzyl-3,4-ethylenedioxypyrrole-quinodimethanediyl)] (PbEDOP-b). The polymerization mixture was n-benzyl-3,4-ethylenedioxypyrrole (300 mg, 1.39 mmol), benzaldehyde (174.34 mg, 1.61 mmol), 4 mL of p-dioxane, and 47 mg (0.46 mmol) of 98% sulfuric acid.…”
Section: Synthesismentioning
confidence: 99%
“…[1][2][3] Representative small band gap polymers include poly(isothianaphthene) (PITN), 13,14 poly(thiophene methine) (PTMs), [15][16][17][18] polysquaraines, 3 poly-(thiopyrazine), 19,20 poly(cyclopentadithiophene), 21 poly(thieno- [3,4,b]thiophene), 22 and ladder polymers. [1][2][3] Conjugated polymers with alternating aromatic and quinoid isomers were shown to have intrinsic small band gaps, including poly(thiophene methine) (PTM), [15][16][17][18] poly(isothianaphthene methine), 23,24 poly(pyrrole methine), 25 and poly-[(3,4-ethylenedioxythiophene-2,5-diyl) methine]. [26][27][28] In particular, the methine bridged conjugated polymers with the thiophene backbone exhibited relatively smaller band gap less than 1.0 eV.…”
Synthesis and electronic properties of new small band gap conjugated polymers, methine-bridged poly(3,4-ethylenedioxypyrrole) (PEDOP) are reported. Density functional theory (B3LYP with 6-31G basis) are used to obtain the optimized ground-state geometries and electronic structures of PEDOP and poly [(3,4-ethylenedioxypyrrole-2,5-diyl) methine] (PEDOP-M). Theoretical bond length alternation of PEDOP is reduced by incorporating the methine bridge and leads to the band gap reduction from 2.44 to 0.68 eV. The small band gap characteristic of PEDOP-M is further verified by preparing two conjugated polymers, poly[(2,5-n-benzyl-3,4-ethylenedioxypyrrolediyl)-benzylidene-(2,5-n-benzyl-3,4-ethylenedioxypyrrole-quinodimethanediyl)] (PbEDOP-b) and poly[(2,5-n-benzyl-3,4-ethylenedioxypyrrolediyl)-(p-nitrobenzylidene)-(2,5-nbenzyl-3,4-ethylenedioxypyrrole-quinodimethanediyl)] (PbEDOP-nb). The optical band gap of PbEDOP-b and PbEDOPnb are 1.77 and 1.45 eV, respectively, while the electrochemical band gap of the former is 1.59 eV. Although the bulky side groups of these two polymers result in a larger band gap than that of PEDOT-M, it indicates the small band gaps of such polymers. The nitrobenzene group could extend the -conjugation and lead to the smaller band gap of PbEDOP-nb than that of PbEDOP-b. The present study suggests that methine-bridged poly(3,4-ethylenedioxypyrrole) is a class of small band gap polymers.
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.
