Theoretical Investigations into the Structural and Electronic Influences on the Hydrogen Bonding in Doped Polyaniline

Foreman, Joel P.; Monkman, Andrew P.

doi:10.1021/jp030398w

Cited by 54 publications

(35 citation statements)

References 25 publications

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“…Similar calculations are performed on aniline for comparison purposes. This particular combination of functional and basis set is widely accepted as being applicable to such systems and has been successfully used recently on very similar compounds [20]. We note that a complete description of r-conjugation would require an examination into how the amount of HF exchange in the hybrid functionals affects the accuracy of the data [29].…”

Section: Methodsmentioning

confidence: 99%

“…Previous work by this group on the structural and electronic effects on the hydrogen bonding in doped PANi [20] concluded that the creation of a hydrogen bond between the polymer and its dopant increases the ability of the PANi backbone to conduct. That analysis is very similar in methodology to work presented here, and the two papers can be considered complimentary.…”

Section: Introductionmentioning

confidence: 99%

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Alkyl Substituent Effects on the Conductivity of Polyaniline

Zaidi

Foreman

Tzamalis

et al. 2004

Adv Funct Materials

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The oxidative polymerization of aniline hydrochloride derivatives in water at low temperature is studied without lithium chloride. The resulting polymers have high molecular weight but the conductivity of the acid‐doped films is strongly dependent on the alkyl‐substituted chain at the 2‐positions. The root cause of the alkyl‐substitution effects is thoroughly investigated using density functional theory (DFT) methods (B3LYP using 6–1G(d,p) and 6‐311++G(2d,2p) basis sets). Internal structural changes observed on substitution appear to be more significant than a variety of electronic parameters measured using the natural bond orbital (NBO) method. Interplanar angles steadily increase on substitution, whereas ring orbital properties and the amount of ring delocalization remain fairly constant. An investigation into the extent to which lone pair–σ‐orbital overlap is affected by substitution indicates that increasing the steric bulk of the substituent reduces the ability of the lone pair to delocalize into the ring orbitals. However, the amount of overlap between the two is not adversely affected until the dihedral between them is > 30°, a situation that only occurs in i‐propyl and s‐butyl substitution. This finding is completely reflected in the experimental conductivity measurements.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Alkyl Substituent Effects on the Conductivity of Polyaniline

Zaidi

Foreman

Tzamalis

et al. 2004

Adv Funct Materials

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“…49 In addition, this hypothesis was backed up by density functional theory calculations on a semiconducting polymer. 50 Furthermore, in a study on oriented LEPs ͑MEH-PPV͒ in a nanoscale architecture it was observed that the electronic energy transfer is more efficient between individual polymer chains then along the chain. 51 As the rate of energy transfer is directly related to the coupling strength 52 the conclusion of that study is that interchain interactions are stronger than the intrachain interactions.…”

Section: Circular Dichroismmentioning

confidence: 99%

Polarized optical spectroscopy applied to investigate two poly(phenylene-vinylene) polymers with different side chain structures

Pålsson

Vaughan

Monkman

2006

The Journal of Chemical Physics

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Two related poly͑phenylene-vinylene͒ ͑PPV͒ light-emitting polymers have been investigated by means of polarized optical spectroscopy. The purpose of the investigation was to investigate the nature of the interactions in thin films and to examine what impact the difference in side chain structure and molecular weight in poly͑2Ј-methoxy-5-2-ethyl-hexoxy͒-1,4-phenylene vinylene ͑MEH-PPV͒ and poly͑2-͑3Ј ,7Ј-dimethyloctyloxy͒-5-methoxy-1,4-phenylene-vinylene͒ ͑OC 1 C 10 -PPV͒ has on the electronic and optical properties of the two polymers. Aligning the polymers by dispersing them in anisotropic solvents and stretched films shows that the side chains have an impact on the relative orientations of the transition dipole moments. In anisotropic solvents the linear dichroism is larger for MEH-PPV than for the related polymer OC 1 C 10 -PPV, while in stretched films the opposite situation prevails. A lower polarization of the luminescence from OC 1 C 10 -PPV, relative to MEH-PPV, was also obtained independent of alignment medium used. The data therefore suggest that while mechanical stretching may align the OC 1 C 10 -PPV to a greater degree, the emitting species is distinct from the absorbing species. The circular dichroism ͑CD͒ spectra of both polymers undergo dramatic changes when the liquid phase and the solid state ͑film͒ are compared. The solution CD spectra shows no evidence of interchain interactions; instead the spectra of both systems indicate a helical conformation of the polymers. The CD spectra of films are dramatically different with the strong Cotton effect being observed. This points to the formation of an aggregate in the film, with an associated ground state interaction, an interchain species such as a physical dimer, or a more complex higher aggregate.

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“…The theoretical investigations dedicated to PANI are also plentiful and cover almost all computational levels, i.e., molecular mechanics and dynamics [17] (doping mechanism, proton migration, temperature dependence of absorption, and conductivity), Monte Carlo [18,19] (interchain electronic transport in disordered systems), Hü ckel [20] (band structure, DOS), semi-empirical methods [21,22] (structure, UV/VIS spectra), as well as firstprinciple methods such as Hartree-Fock and DFT [23][24][25][26][27][28] (structure, infrared and Raman spectra). Some semi-empirical calculations are performed for the evaluation of torsion barriers and solvation effects on the UV/VIS spectra of PANI chains, accounted for by models including 2 to 4 solvent molecules [29,30].…”

Section: Introductionmentioning

confidence: 99%

Theoretical study of the structure and electronic spectra of fully protonated emeraldine oligomers

Zhekova

Tadjer

Ivanova

et al. 2006

Int J of Quantum Chemistry

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Polyaniline (PANI) is one of the most studied conducting polymers.Obtained in its conducting form (known as "emeraldine salt") by chemical or electrochemical oxidation of aniline in aqueous acidic medium, this polymer manifests an array of attractive properties. Nevertheless, these properties still need to be described at the molecular level. Intense theoretical investigations during the past few years aim at explaining the chain organization, conductivity mechanism, and other structural and spectral characteristics. Most studies adopt simplified models in which hydration effect is underestimated, since all simulations are performed either in vacuum or in the presence of a limited number of water molecules. The present computational study sheds light on the molecular organization of a number of model PANI hydrated clusters with different alignment and multiplicity, which can explain the experimentally recorded UV/VIS spectra. The influence of hydration and interaction with adjacent oligomers is estimated. Short-chain doubly protonated emeraldine oligomers are used as model systems. The calculations are performed at the semi-empirical (AM1) and/or molecular mechanics (AMBER96) level. Proper configurations of the clusters are selected using Monte Carlo simulations. Electron correlation (CIS) is accounted for upon evaluation of the absorption spectra of the clusters. The relative strength of the interchain coupling is estimated by simulation of PANI clusters consisting of two PANI tetramers in water. Comparison to experimental results is made.

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Theoretical Investigations into the Structural and Electronic Influences on the Hydrogen Bonding in Doped Polyaniline

Cited by 54 publications

References 25 publications

Alkyl Substituent Effects on the Conductivity of Polyaniline

Alkyl Substituent Effects on the Conductivity of Polyaniline

Polarized optical spectroscopy applied to investigate two poly(phenylene-vinylene) polymers with different side chain structures

Theoretical study of the structure and electronic spectra of fully protonated emeraldine oligomers

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