Investigation of Barriers To Conformational Interchange in Oligothiophenes and Oligo(Thienyl)furans

Diaz-Quijada, Gerardo A.; Weinberg, Noham; Holdcroft, Steven; Pinto, B. Mario

doi:10.1021/jp011783t

Cited by 49 publications

(53 citation statements)

References 61 publications

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“…The comparison of the calculated structures with experimental X-ray data as well as gas-phase and solution conformational studies has also been carried out (see Diaz-Quijada et al (2002) for review). Most of these studies have concentrated on the rotational barrier and its impact on the spectroscopic and photophysical properties of oligothiophenes.…”

Section: (B ) Geometrymentioning

confidence: 99%

Hole-vibronic coupling in oligothiophenes: impact of backbone torsional flexibility on relaxation energies

Filho

Coropceanu

Fichou

et al. 2007

Phil. Trans. R. Soc. A.

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Density functional theory calculations together with highly resolved gas-phase ultraviolet photoelectron spectroscopy have been applied to oligothiophene chains with up to eight thiophene rings. One of the important parameters governing the charge transport properties in the condensed phase is the amount of energy relaxation upon ionization. Here, we investigate the impact on this parameter of the backbone flexibility present in oligothiophenes as a result of inter-ring torsional motions. With respect to oligoacenes that are characterized by a coplanar and rigid backbone, the torsional flexibility in oligothiophenes adds to the relaxation energy and leads to the broadening of the first ionization peak, making its analysis more complex.

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Section: (B ) Geometrymentioning

confidence: 99%

Hole-vibronic coupling in oligothiophenes: impact of backbone torsional flexibility on relaxation energies

Filho

Coropceanu

Fichou

et al. 2007

Phil. Trans. R. Soc. A.

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show abstract

“…There are no known data on the gasphase geometry of alkylated oligothiophenes. The closest match is a dynamic NMR study which found that alkylated dimers interconverted rapidly between syn-like and anti-like forms even at 140 K, and thus inferred that the barrier between configurations is very low [41]. Ab initio studies at levels of theory ranging from HF/3-21G* to HF/6-31G** also suggest a low barrier to ring rotation in oligo(alkylthiophenes), and that the addition of side chains should favor a geometry that is further deplanarized compared to plain oligothiophene [45,59,43].…”

Section: Geometry and Partial Chargesmentioning

confidence: 91%

“…Perhaps the most important reason is that existing AMBER force fields were parameterized at this level of theory [38], and consistency with the existing parameters is a primary goal of our work. However, another deciding factor is that HF/6-31G* optimizations and rotations have been shown by other investigators to match well with experimental results [39], and the use of higher levels of theory (e.g., MP2) does not substantially change the relative energies of different conformations [40,41].…”

Section: Geometry and Partial Chargesmentioning

confidence: 98%

Development and initial testing of an empirical forcefield for simulation of poly(alkylthiophenes)

Widge

Matsuoka

Kurnikova

2008

Journal of Molecular Graphics and Modelling

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Conductive polymers from the polythiophene (PT) family have attracted interest in numerous domains, including potential applications in biosensing. Despite this, atomistic simulations of PTs have tended to use general organic force fields without well-tuned PT parameters, and there exists no optimized and well-validated PT force field that is compatible and consistent with existing biomolecular simulation suites. We present here the development of a new PT forcefield following the AMBER approach, using the program ANTECHAMBER and ab initio calculations at the HF/6-31G* level of theory to assign partial charges and parameterize the critical backbone torsion potential. The optimized geometries and force field potentials match well with both empirical data and previous investigators' calculations. Initial testing of these parameters through a series of replica exchange simulations of two PT derivatives in aqueous and organic implicit solvents demonstrates that the parameters can match empirical expectations within the limits of an implicit solvent model. This new force field forms a framework for modeling of proposed PT-based devices and sensors, and is expected to accelerate device design and eventual deployment.

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“…15,[19][20][21] However, the transferability of force-field parameter sets derived from small and simple model molecules to polymers with complex chemical architectures, as for instance PT-c4as, is not always accurate enough. Thus, PT-c4as typically present an alternated distribution of flexible and rigid dihedral angles in the backbone because each calix [4]arene macrocycle connects two adjacent thiophene rings.…”

Section: Introductionmentioning

confidence: 99%

Parameterization of the torsional potential for calix[4]arene‐substituted poly(thiophene)s

et al. 2009

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Three different strategies have been followed to develop the torsional force-field parameters of the inter-ring dihedral angles for calix[4]arene-substituted poly(thiophene)s, a family of highly sensitive ion receptors. These procedures, which are based on the rotational profiles calculated using quantum mechanical methods, differ in the complexity of the model compounds and the processing applied to the quantum mechanical energies before the fitting. The performance of the three sets of developed parameters, which are essentially compatible with the General Amber Force Field, has been evaluated by computing the potential of mean forces for the inter-ring rotation of 2,2'-bithiophene, and its substituted analog bearing a calix[4]arene group in different environments. Finally, the ability of the new sets of torsional parameters to describe a calix[4]arene-substituted poly(thiophene) in tetrahydrofuran solution has been checked using Molecular Dynamics simulations. Specifically, the molecular shape, the polymer conformation, and the effects of the Na(+) ions trapped in the cavity of the receptor have been examined. Although the potential derived from unsubstituted 2,2'-bithiophene is able to reproduce the experimental free energies of the minima, the overall results indicate that the parameters derived from the analog bearing a calix[4]arene group provide the best description of the systems under study. This should be attributed to the strong constraints found in complex substituted poly(thiophene)s, which require parameterization strategies able to capture all the interactions and phenomena involved in their inter-ring rotations.

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Investigation of Barriers To Conformational Interchange in Oligothiophenes and Oligo(Thienyl)furans

Cited by 49 publications

References 61 publications

Hole-vibronic coupling in oligothiophenes: impact of backbone torsional flexibility on relaxation energies

Hole-vibronic coupling in oligothiophenes: impact of backbone torsional flexibility on relaxation energies

Development and initial testing of an empirical forcefield for simulation of poly(alkylthiophenes)

Parameterization of the torsional potential for calix[4]arene‐substituted poly(thiophene)s

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