Conformational Study of Poly(<i>p</i>-phenylene) by Molecular Mechanics Minimization

Park, Kang C.; Dodd, Lawrence R.; Levón, Kalle; Kwei, T. K.

doi:10.1021/ma960607t

Cited by 40 publications

(24 citation statements)

References 16 publications

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“…[6][7][8][9][10][11][12] Films of oligomers that contain up to 9 benzene rings can be fabricated by vacuum deposition, [13,14] but solution processing methods are needed for large area films. Soluble substituted PPPs 2 bearing alkyl or alkoxy groups have been made by a variety of methods, [15] but steric interactions between the side-chains induce a marked out-of-plane torsion of adjacent benzene rings, [16] so that the conjugation along the backbone in these polymers is much reduced, making them violet-emitters. One major feature of research into phenylene-based materials has been to reconcile the need to use solubilizing groups to obtain processability with the desire to retain the favourable electronic properties of the parent PPP.…”

Section: Introductionmentioning

confidence: 99%

Oligomers and Polymers Based on Bridged Phenylenes as Electronic Materials

Grimsdale

Müllen

2007

Macromol. Rapid Commun.

192

154

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The synthesis, properties, and application in electronic devices of ladder and step‐ladder phenylene‐based oligomers and polymers are reviewed with an emphasis on control of properties by synthetic design. Bridged polyphenylenes can be prepared with a range of different amounts and types of bridges. Fully bridged polymers suffer the problem of incomplete formation of bridges during polymer analogous reactions. This problem is surmounted by the synthesis of regular stepladder polymers in which the monomers are well‐characterized oligo(ladder‐phenylene)s. By controlling the degree of bridging and thus the planarity of the polymer, its optical properties can be tuned. The optical and electronic properties can be further controlled by means of the type of bridges used.

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Section: Introductionmentioning

confidence: 99%

Oligomers and Polymers Based on Bridged Phenylenes as Electronic Materials

Grimsdale

Müllen

2007

Macromol. Rapid Commun.

192

154

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“…Dieter Schlüter and Gerhard Wegner [79,[113][114][115][116] introduced the Suzuki coupling [49,117] for the synthesis of poly(dialkylphenylene)s, marking a milestone for the synthesis of conjugated polymers (Scheme 1). However, the alkyl substituents required for solubilization cause significant torsion about the inter-ring bonds and thus hamper extended π-conjugation [118,119].…”

Section: Ribbon (Or Ladder) Polymersmentioning

confidence: 99%

Graphene as a Target for Polymer Synthesis

Müllen

2013

Advances in Polymer Science

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Graphene has remarkable physical properties, but existing production methods have severe deficiencies that limit its potential use in robust technologies. Opening a reliable and efficient synthetic route to graphene and its functionalized derivatives offers a path to overcome this obstacle for its practical application. Graphene can be regarded as a two-dimensional polymer (2D), and it is here argued that it, along with its derivatives, represents a realistic yet challenging target for polymer synthesis.In order to demonstrate the possibility of such syntheses, an overview is presented on the evolution of phenylene-based macromolecules. It is shown how classical linear polyphenylenes can be expanded to increasingly more sophisticated structures involving two-and three-dimensional (3D) polyphenylene architectures. A crucial aspect of the meticulous synthetic design of these molecules has been the avoidance of defects within the structures, resulting in the precise control of their physical, especially optoelectronic, properties.Linear conjugated polymers with defined optical properties have been made by controlling the degree of torsion between the benzene rings. This has included the development of efficient routes to ladder-type polymers and of step-ladder materials. Planar graphene molecules, or nanographenes, in a range of sizes and shapes have been fabricated by the controlled cyclodehydrogenation of 3D polyphenylene dendrimers. By combining knowledge gained from the synthesis of conjugated polymers, polyphenylene dendrimers, and nanographenes, it has proven feasible to make, either by solution or surface-bound methods, graphene nanoribbons with well-defined structures. These functional materials possess properties similar to graphene while displaying improved processability.Finally, we review less-sophisticated paths towards graphene materials involving processing of graphene oxide, its reduction, and its hybridization with other components. These too have a role to play in acquiring functional graphenes where K. Müllen (*) Max-Planck-Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany e-mail: muellen@mpip-mainz.mpg.de a lesser degree of control over the properties is required. This voyage of exploration towards the precise synthesis of conjugated phenylene-based polymers has thus had the dual objectives of fundamental research and practical materials science. En route we have had to meet the sometimes conflicting gauntlets thrown down by these two aims, which has at times involved trade-offs between the theoretically desirable and the reasonably accessible.

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“…[35,[91][92][93][94][95]). Nevertheless, the counterpart of the gain of solubility induced by side groups is the decrease of the p-conjugation by twisting of aromatic nuclei out-of-plane with torsion angles from around 20 in PPP up to 70 in substituted PPPs [96]. As a result, electronic conjugation is reduced and thus, HOMO-LUMO gap is increased (3.0-3.2 eV), resulting in a blue-shifted emission generally accompanied by a decrease of electroluminescence quantum yield [6].…”

Section: External Quantum Efficiencymentioning

confidence: 99%