Synthesis and characterization of polythiophene derivatives with nitrogen heterocycles on the side chain

Takagi, Koji; Kawagita, Eiki; Kouchi, Ryo

doi:10.1002/pola.27228

Cited by 12 publications

(8 citation statements)

References 48 publications

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“…The CTP pathway can undergo unproductive reactions when the catalyst’s electronic and steric properties are mismatched for a specific monomer (Scheme ). For example, if the metal−π associative intermediate is weakly associated, other species in the reaction mixture (e.g., a coordinating solvent or un/activated monomer) can displace the growing polymer from the catalyst, resulting in chain transfer. , Alternatively, polymer chains can be exchanged between catalysts, producing two new active catalysts along with a polymer of twice the molecular weight via disproportionation . Finally, slow precatalyst initiation continuously generates new chains throughout the polymerization .…”

Section: Introductionmentioning

confidence: 99%

Matchmaking in Catalyst-Transfer Polycondensation: Optimizing Catalysts based on Mechanistic Insight

2016

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Catalyst-transfer polycondensation (CTP) has emerged as a useful living, chain-growth polymerization method for synthesizing conjugated (hetero)arene-based polymers with targetable molecular weights, narrow dispersities, and controllable copolymer sequences-all properties that significantly influence their performance in devices. Over the past decade, several phosphine- and carbene-ligated Ni- and Pd-based precatalysts have been shown to be effective in CTP. One current limitation is that these traditional CTP catalysts lead to nonliving, non-chain-growth behavior when complex monomer scaffolds are utilized. Because these monomers are often found in the highest-performing materials, there is a significant need to identify alternative CTP catalysts. Recent mechanistic insight into CTP has laid the foundation for designing new catalysts to expand the CTP monomer scope. Building off this insight, we have designed and implemented model systems to identify effective catalysts by understanding their underlying mechanistic behaviors and systematically modifying catalyst structures to improve their chain-growth behavior. In this Account, we describe how each catalyst parameter-the ancillary ligand(s), reactive ligand(s), and transition metal-influences CTP. As an example, ancillary ligands often dictate the turnover-limiting step of the catalytic cycle, and perhaps more importantly, they can be used to promote the formation of the key intermediate (a metal-arene associative complex) and its subsequent reactivity. The fidelity of this intermediate is central to the mechanism for the living, chain-growth polymerization. Reactive ligands, on the other hand, can be used to improve catalyst solubility and accelerate initiation. Additional advantages of the reactive ligand include providing access points for postpolymerization modification and synthesizing polymers directly off surfaces. While the most frequently used CTP catalysts contain nickel, palladium-based catalysts exhibit a higher functional group tolerance and broader substrate scope (e.g., monomers with boron, magnesium, tin, and gold transmetalating agents). Overall, we anticipate that applying the tools and lessons detailed in this Account to other monomers should facilitate a better "matchmaking" process that will lead to new catalyst-transfer polycondensations.

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Section: Introductionmentioning

confidence: 99%

Matchmaking in Catalyst-Transfer Polycondensation: Optimizing Catalysts based on Mechanistic Insight

2016

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“…Additional monomers are then added sequentially to the same growing polymer chain during propagation via consecutive transmetalation, reductive elimination, and oxidative addition. Unproductive pathways can occur when complex I is either too stable or unstable. − …”

Section: Introductionmentioning

confidence: 99%

Mechanistic Insight into Thiophene Catalyst-Transfer Polymerization Mediated by Nickel Diimine Catalysts

et al. 2017

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Catalyst-transfer polymerization (CTP) is a living, chain-growth method for accessing conjugated polymers with control over their length and sequence. Typical catalysts utilized in CTP are either Pd or Ni complexes with bisphosphine or N-heterocyclic carbene ancillary ligands. More recently, diimine-ligated Ni complexes have been employed; however, in most cases nonliving pathways become dominant at high monomer conversions and/or low catalyst loading. We report herein an alternative Ni diimine catalyst that polymerizes 3-hexylthiophene in a chain-growth manner at low catalyst loading and high monomer conversion. In addition, we elucidate the chain-growth mechanism as well as one chain-transfer pathway. Overall, these studies provide insight into the mechanism of conjugated polymer synthesis mediated by Ni diimine catalysts.

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“…The reaction occurred at the 2‐position in the 86% selectivity to give 5‐bromo‐2‐chloromagnesio‐3‐(5′‐hexylpyridine‐2′‐yl)thiophene. Subsequently, the Kumada coupling polymerization was carried out using Ni(dppp)Cl 2 (3 mol %) for 2 h to obtain a homopolymer ( P3PT ) having the number‐averaged molecular weight of 13,900 . Although 5‐bromo‐2‐chloromagnesio‐3‐(5′‐hexylpyridine‐2′‐yl)thiophene has the bulky substituent at the ortho position relative to the chloromagnesio group and is regarded as the reverse monomer, the polymerization smoothly proceeded at the refluxing temperature probably due to the chelation effect of the pyridine nitrogen .…”

Section: Resultsmentioning

confidence: 99%

“…The synthesis and characterization of poly[3-(5 0 -hexylpyridine-2 0 -yl)thiophene] (P3PT) was described previously. 24 Instrumentations 1 H nuclear magnetic resonance ( 1 H NMR) spectra were measured on Bruker (Billerica, MA) AVANCE 200 and 500 FT-NMR spectrometers in CDCl 3 , CD 3 OD, and THF-d 8 . Gel permeation chromatographic (GPC) analyses were carried out on a Shodex (Tokyo, Japan) GPC-104 system using tandem LF-404 columns (THF as an eluent, flow rate 5 1.0 mL/ min, 40 C) equipped with an ultraviolet (UV) detector (Shimadzu SPP-20A).…”

Section: Methodsmentioning

confidence: 99%

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Aggregation of polythiophene homopolymer and block copolymer in solution utilizing the characteristics of pyridine at the side chain

Takagi

Kawagita

Kouchi

et al. 2014

J. Polym. Sci. Part A: Polym. Chem.

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Poly[3-(5 0 -hexylpyridine-2 0 -yl)thiophene] (P3PT) (M n 5 13900, H-T content 5 90%) was prepared by the regioselective Grignard metathesis reaction and the subsequent Kumada coupling polymerization. Likewise, poly(3-hexylthiophene)-b-poly[3-(5 0 -hexylpyridine-2 0 -yl)thiophene] (P3HT-b-P3PT) (M n 5 17,300) was synthesized in the one-pot and successive monomer addition protocol, in which the segment ratio was calculated to be 56 (P3HT)/44 (P3PT) base on the 1 H NMR spectrum. The absorption and emission spectra of homopolymer P3PT(H), obtained by the protonation of the pyridine nitrogen, in THF/cyclohexane shifted to the longer wavelength as compared with those collected in THF, suggesting the aggregation in poor solvent. The aggregation of P3PT induced by the addition of Sc(OTf) 3 could be controlled by the molar ratio of pyridine and scandium complex. The protonated block copolymer P3HT-b-P3PT(H) was also subjected to the aggregate formation. The absorption maximum in THF/CH 3 OH showed a bathochromic shift and the fluorescence emission was almost quenched. From the 1 H NMR spectra and DLS measurements, P3HT-b-P3PT(H) forms nanometer scale aggregates particularly with the insolubility and stacking of non-ionic P3HT in alcohol as the driving force.

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Synthesis and characterization of polythiophene derivatives with nitrogen heterocycles on the side chain

Cited by 12 publications

References 48 publications

Matchmaking in Catalyst-Transfer Polycondensation: Optimizing Catalysts based on Mechanistic Insight

Matchmaking in Catalyst-Transfer Polycondensation: Optimizing Catalysts based on Mechanistic Insight

Mechanistic Insight into Thiophene Catalyst-Transfer Polymerization Mediated by Nickel Diimine Catalysts

Aggregation of polythiophene homopolymer and block copolymer in solution utilizing the characteristics of pyridine at the side chain

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