Structure and Segmental Motions in a Substituted Polythiophene: A Solid‐State NMR Study

Bouch, Nolwenn Le; Auger, Michèle; Leclerc, Mario

doi:10.1002/macp.200800365

Cited by 14 publications

(10 citation statements)

References 32 publications

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“…In order to understand a little more about the JCA concept and to obtain in-depth information on its behavior with the electronic properties of other polymeric carbon chains, we investigate the growth of small chains of polyacetylene and polythiophene within the oligomer approach. As is known, these systems form π-conjugated polymers and are of interest for several technological applications in the group of organic conductive polymers. ,− Again, as far as we know, detailed studies on the 13 C NMR SSCCs of these materials are scarce in the literature, mainly because of the oscillatory pattern of the individual 1 J CC couplings (see Figures S2 and S3), so that the studies are more focused on the determination of chemical shifts. , However, here it is also illustrative to investigate this zigzag behavior of 1 J CC in terms of JCA for other polymeric chains, as displayed in Figure a and b.…”

Section: Resultsmentioning

confidence: 95%

“…42,65−67 Again, as far as we know, detailed studies on the 13 C NMR SSCCs of these materials are scarce in the literature, 41 mainly because of the oscillatory pattern of the individual 1 J CC couplings (see Figures S2 and S3), so that the studies are more focused on the determination of chemical shifts. 68,69 However, here it is also illustrative to investigate this zigzag behavior of 1 J CC in terms of JCA for other polymeric chains, as displayed in Figure 8a and 8b.…”

Section: J-couplingmentioning

confidence: 97%

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Close Relationships between NMR J-Coupling Alternation (JCA) and Molecular Properties of Carbon Chains

Oliveira

Rivelino

2019

J. Chem. Theory Comput.

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We propose a J-coupling alternation (JCA) value that is demonstrated to be a suitable parameter to evaluate the nuclear magnetic resonance (NMR) indirect spin−spin coupling constants (SSCCs) as a function of molecular properties of chains by increasing their length. As an application, we report a theoretical study of the SSCCs for the interactions between neighbor nuclei in increasingly patterned carbon chains within density functional theory. First, we examine the J-coupling constants between 1 H and 13 C nuclei ( n J HC ) considering the separation distance, as well as between two adjacent 13 C nuclei ( 1 J CC ) considering their relative positions in polyynes and cumulenes. Further, we define and determine JCA in terms of the differences of 1 J CC , which is investigated as a function of several molecular properties, e.g., cohesive energy, characteristic vibrational frequency, average polarizability, and energy gap of the systems. We also determine JCA for other types of carbon chains, such as diphenyl-capped polyynes, polyacetylene and polythiophene. The behavior of JCA as a function of the energy gap may be related to highly π-conjugated low-band-gap carbon chains. Overall, JCA correlates very well with the electronic properties of these chains, especially with their energy gap, exhibiting positive values for pristine polyyne and polythiophene and negative values for pristine cumulene and plyacetylene. These findings indicate an alternative way to establish an appropriate SSCC descriptor that characterizes the electronic nature of the system, such as the proposed JCA value averaging the whole system, instead of using only the individual J-coupling values to give insights into the properties of large and extended systems.

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Section: Resultsmentioning

confidence: 95%

Section: J-couplingmentioning

confidence: 97%

Close Relationships between NMR J-Coupling Alternation (JCA) and Molecular Properties of Carbon Chains

Oliveira

Rivelino

2019

J. Chem. Theory Comput.

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“…Temperature-controlled order-disorder transitions have been previously studied in solutions of non-ionic polymers such as polythiophenes 9,45 and analogues of PPV (poly(p-phenylene vinylene)), 46,47 confirming that the intra-and interchain electronic coupling resulting from the molecular conformation and aggregation can be tuned with temperature. 46 Some reports of thermochromic behaviour have appeared about CPEs, 48,49 however, those are limited to the stationary optical properties.…”

Section: Introductionmentioning

confidence: 97%

Salt-induced thermochromism of a conjugated polyelectrolyte

Peterhans

Alloa

Sheima

et al. 2017

Phys. Chem. Chem. Phys.

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We report here the photophysical properties of a water-soluble conjugated polythiophene with cationic side-chains. When dissolved in aqueous buffer solution (PBS, phosphate buffered saline), there is ordering of the polymer chains due to the presence of the salts, in contrast to pure water, where a random-coil conformation is adopted at room temperature. The ordering leads to a pronounced colour change of the solution (the absorption maximum shifts from 400 nm to 525 nm). Combining resonance Raman spectroscopy with density functional theory computations, we show a significant backbone planarization in the ordered phase. Moreover, the ratio of ordered phase to random-coil phase in PBS solution, as well as the extent of intermolecular interactions in the ordered phase, can be tuned by varying the temperature. Femtosecond transient absorption spectroscopy reveals that the excited-state behaviour of the polyelectrolyte is strongly affected by the degree of ordering. While triplet state formation is favoured in the random-coil chains, the ordered chains show a weak yield of polarons, related to interchain interactions. The investigated polyelectrolyte has been previously used as a biological DNA sensor, based on optical transduction when the conformation of the polyelectrolyte changes during assembly with the biomolecule. Therefore, our results, by correlating the photophysical properties of the polyelectrolyte to backbone and intermolecular conformation in a biologically relevant buffer, provide a significant step forward in understanding the mechanism of the biological sensing.

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“…1. Characterization of polythiophenes was extensively studied by solid state NMR spectroscopy [8,9], MALDI-TOF analyses [1011], and UV-vis spectroscopy [7]. To characterize the photogenerated oligo(thiophene), photogenerated oligo(3-hexylthiophene) was used due to the high solubility in solvents.…”

Section: Photopolymerization Of Thiophenementioning

confidence: 99%