Theoretical analysis of effects of π-conjugating substituents on building blocks for conducting polymers

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dc.citation.epage7425en_US
dc.citation.issueNumber20en_US
dc.citation.spage7419en_US
dc.citation.volumeNumber64en_US
dc.contributor.authorSalzner, U.en_US
dc.contributor.authorLagowski, J. B.en_US
dc.contributor.authorPickup, P. G.en_US
dc.contributor.authorPoirier, R. A.en_US
dc.date.accessioned2016-02-08T10:40:47Z
dc.date.available2016-02-08T10:40:47Z
dc.date.issued1999en_US
dc.departmentDepartment of Chemistryen_US
dc.description.abstractGeometries of 4-dicyanomethylene-4H-cyclopenta[2,1-b:3,4-b'] dithiophene 1 and its C=O, C=S, C=CH2, C=CF2, and C=C(SR)2 analogues were optimized using density functional theory. Three of the above groups, C=C(CN)2, C=O, and C=S, were also examined on dipyrrole, difuran, dicyclopentadiene, and diborole. Electronic structures were analyzed with respect to their suitability as building blocks for conducting polymers with the natural bond orbital (NBO) method. All bridging groups investigated decrease HOMO-LUMO gaps compared to the unsubstituted parent dimers. Substitution affects HOMO and LUMO energies. Energy gap reduction is caused by a stronger decrease of LUMO energies compared to HOMO energies. The C=S group leads to even smaller energy gaps than the dicyanomethylene group since the HOMO is lowered less in energy with C=S. Compared to unsubstituted dimers, the strongest substituent effects are found with pyrroles and furans. Boroles and thiophenes are least affected. The smallest HOMO-LUMO gaps are obtained for electron-poor systems such as boroles followed by cyclopentadienes. This is analogous to the trend for the unsubstituted parent systems. All of the bridging groups are potential π-acceptors due to their low-lying π*-orbitals, and the corresponding polymers are predicted to be n-dopable. In aromatic structures, the LUMO is localized around the bridging substituent and the coefficients at the α-carbon atoms that reflect electron density are small. This might contribute to the poor conductivity of the n-doped form of poly-1. Electron- poor monomers and polymers tend to switch to quinoid structures. In quinoid repeat units, the HOMO is localized but not as strongly as the LUMO in the aromatic repeat units. The LUMO in quinoid repeat units is delocalized with large coefficients at the α-carbon atoms. Quinoid polymers could therefore be good conductors in the n-doped state.en_US
dc.description.provenanceMade available in DSpace on 2016-02-08T10:40:47Z (GMT). No. of bitstreams: 1 bilkent-research-paper.pdf: 70227 bytes, checksum: 26e812c6f5156f83f0e77b261a471b5a (MD5) Previous issue date: 1999en
dc.identifier.doi10.1021/jo990725pen_US
dc.identifier.issn0022-3263
dc.identifier.urihttp://hdl.handle.net/11693/25202
dc.language.isoEnglishen_US
dc.publisherAmerican Chemical Societyen_US
dc.relation.isversionofhttp://dx.doi.org/10.1021/jo990725pen_US
dc.source.titleJournal of Organic Chemistryen_US
dc.subjectCyclopentadiene derivativeen_US
dc.subjectFuran derivativeen_US
dc.subjectPolymeren_US
dc.subjectPyrrole derivativeen_US
dc.subjectThiophene derivativeen_US
dc.subjectChemical analysisen_US
dc.subjectChemical structureen_US
dc.subjectConductanceen_US
dc.subjectConjugationen_US
dc.subjectControlled studyen_US
dc.subjectGeometryen_US
dc.titleTheoretical analysis of effects of π-conjugating substituents on building blocks for conducting polymersen_US
dc.typeArticleen_US

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