Phase Tag-Assisted Synthesis of Benzo[<i>b</i>]carbazole End-Capped Oligothiophenes

Levick, Matthew; Coote, S. C.; Grace, Iain; Lambert, Colin J.; Turner, Michael L.; Procter, David J.

doi:10.1021/ol302748h

Cited by 26 publications

(13 citation statements)

References 46 publications

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“…The reactions were quenched by adding pyridine to sequester the Lewis acid, then the polymers were precipitated into MeOH and isolated by vacuum filtration. 10 As a baseline, the reaction of unsubstituted oPA (M5) produced cPPA (P5) in 35% isolated yield (Table 1, entry 5). Propoxy-substituted M1, butylthio-substituted M2, and hexyl-substituted M3 all possess estimated ceiling temperatures < -78 °C and were therefore not expected to generate polymer under these conditions.…”

Section: Scheme 2 Model Reaction For Phthalaldehyde Polymerizationmentioning

confidence: 99%

“…Dimethyl 4,5-dihexylphthalate (S3c). 10 A 250-mL, 3-neck, round-bottomed flask was charged sequentially with a stir bar, S3b (3.01 g, 13.5 mmol, 1.00 equiv), anhydrous toluene (25 mL), and dimethyl acetylenedicarboxylate (1.7 mL, 14 mmol, 1.00 equiv). The flask was capped with a reflux condenser and stirred in a 120 °C oil bath for 13.5 h. A long needle was used to bubble air through the reaction mixture and stirring was continued at 120 °C for an additional 47.5 h. Reaction progress was assessed by periodically analyzing aliquots of the reaction mixture using 1 H NMR spectroscopy until full conversion of the methylene peak of the intermediate cyclohexadiene (δ 2.95 ppm in CDCl 3 ) was observed.…”

Section: S12mentioning

confidence: 99%

“…8,9 Linear or cyclic PPA (cPPA) can be obtained via anionic or cationic polymerization (respectively) of o-phthalaldehyde (oPA) below its Tc of -36 °C. 10,11 While end-capped linear PPA and cPPA are kinetically stable at room temperature, solution-phase exposure to acid results in complete depolymerization at rates too rapid to measure using standard analytical techniques (< 1 min; Scheme 1). 1 The thermodynamic instability of PPA is key to its depolymerization, but this same property has led to challenges in polymer processing.…”

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Functionalized and Degradable Polyphthalaldehyde Derivatives

et al. 2019

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Polymers that depolymerize back to monomers can be repeatedly chemically recycled, thereby reducing their environmental impact. Polyphthalaldehyde is a metastable polymer that is rapidly and quantitatively depolymerized due to its low ceiling temperature. However, the effect of substitution on the physical and chemical properties of polyphthalaldehyde derivatives has not been systematically studied. Herein, we investigate the cationic polymerization of seven o-phthalaldehyde derivatives and demonstrate that judicious choice of substituents results in materials with a wide range of ceiling temperatures (<-60 to 106 °C) and decomposition temperatures (109-196 °C). We anticipate that these new polymers and their derivatives will enable researchers to access degradable materials with tunable thermal, physical, and chemical properties.

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Section: Scheme 2 Model Reaction For Phthalaldehyde Polymerizationmentioning

confidence: 99%

Section: S12mentioning

confidence: 99%

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confidence: 99%

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Functionalized and Degradable Polyphthalaldehyde Derivatives

et al. 2019

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“…Specifically, TM-DBCOD was synthesized from (4,5-dimethyl-1,2-phenylene)dimethanol (di-OH) on a large scale, sequentially through bromination 49 using phosphorous tribromide and dimerization [50][51] in the presence of lithium sands. 1,10-di-CHO was formed via Rieche formylation.…”

Section: Resultsmentioning

confidence: 99%

Arene Substitution Design for Controlled Conformational Changes of Dibenzocycloocta-1,5-dienes

Alam

et al. 2020

J. Am. Chem. Soc.

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We report that the agile eight-membered cycloalkane can be stabilized by fusing two rigid benzene rings, substituted with proper functional groups. The conformational change of dibenzocycloocta-1,5-diene (DBCOD), a rigid-flexible-rigid organic moiety, from Boat to Chair conformation requires an activation energy of 42 kJ/mol that is substantially lower than that of existing submolecular shape-changing unit. Experimental data corroborated by theory calculations demonstrate that intramolecular hydrogen bonding can stabilize Boat whereas electron repulsive interaction from opposing ester substituents favors Chair. Intramolecular hydrogen bonding, formed by 1,10-diamide substitution stabilizes Boat, spiking the temperature at which Boat and Chair can readily interchange from -60 °C to 60 °C. Concomitantly this intramolecular attraction raises the energy barrier from 42 kJ/mol of unsubstituted DBCOD to 68 kJ/mol of diamide-substituted DBCOD. Remarkably, this value falls within the range of the activation energy of highly efficient enzyme catalyzed biological reactions. With shape changes once considered only possible with high-energy, our work reveals a potential pathway exemplified by a specific submolecular structure to achieve low-energy driven shape changes for the first time. Together with intrinsic cycle stability and high energy output systems that would have incurred damage under high-energy stimuli, could particularly benefit from this new kind of low-energy driven shape-changing mechanism. This work has laid the basis to construct systems for low-energy driven stimuli-responsive applications, hitherto a challenge to overcome.

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Functionalized and Degradable Polyphthalaldehyde Derivatives

Lutz¹,

Davydovich²,

Hannigan³

et al. 2019

Preprint

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<div><p>Polymers that depolymerize back to monomers can be repeatedly chemically recycled, thereby reducing their environmental impact. Polyphthalaldehyde is a metastable polymer that is rapidly and quantitatively depolymerized due to its low ceiling temperature. However, the effect of substitution on the physical and chemical properties of polyphthalaldehyde derivatives has not been systematically studied. In this work, we investigate the cationic polymerization of seven distinct <i>o</i>‑phthalaldehyde derivatives and demonstrate that judicious choice of substituents results in materials with a wide range of ceiling temperatures (from < –60 to 106 °C) and decomposition temperatures (109–196 °C). We anticipate that these new polymers and their derivatives will enable researchers to access degradable materials with tunable thermal, physical, and chemical properties.</p></div>

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Phase Tag-Assisted Synthesis of Benzo[b]carbazole End-Capped Oligothiophenes

Abstract: The introduction and removal of a phase tag have been used to trigger cyclization events in a new synthesis of benzo[b]carbazoles. The approach has been exploited in a tag-assisted approach to new benzo[b]carbazole end-capped oligothiophenes for preliminary evaluation as semiconductors.

Cited by 26 publications

References 46 publications

Functionalized and Degradable Polyphthalaldehyde Derivatives

Functionalized and Degradable Polyphthalaldehyde Derivatives

Arene Substitution Design for Controlled Conformational Changes of Dibenzocycloocta-1,5-dienes

Functionalized and Degradable Polyphthalaldehyde Derivatives

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