Crystal structures, phase transitions and energy calculations of poly(p-phenylene) oligomers

Baker, K. N.; Fratini, Albert; Resch, Timothy J.; Knachel, Howard C.; Adams, W. Wade; Socci, Edward P.; Farmer, Barry L.

doi:10.1016/0032-3861(93)90313-y

Cited by 356 publications

(346 citation statements)

References 44 publications

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“…This fact is also reflected in smaller excitation energies in the absorption spectra obtained for films and crystals in comparison with solvent measurements. 34,35 The calculated average C-C bond lengths between two phenyl rings in the oligophenylenes are 1.485 (twisted) and 1.489 Å (planar), which are similar to the experimental average C-C bond lengths (1.499 Å (4), 29 1.482 Å (5), 33 1.481 Å (6) 33 and 1.479 Å (7) 33 ) of crystal structure. These distances are much shorter than the typical C-C single bond length (1.54 Å) due to the -electron delocalization of the oligo-p-phenylenes.…”

Section: Bcsupporting

confidence: 80%

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Calculated and Experimental UV and IR Spectra of Oligo-para-phenylenes

Park¹,

Lee²,

Yoon³

et al. 2014

Bulletin of the Korean Chemical Society

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The quantum mechanical properties of a series of oligo-para-phenylenes (2-11) were characterized using DFT B3LYP/6-311G(d,p) calculations. The global minimum among the various torsional conformers of an oligo-pphenylene is calculated to be a twist conformation. A less stable planar conformation, in which all the dihedral angles in oligo-p-phenylene are restricted to be planar, has also been calculated. The total electronic energies, normal vibrational modes, Gibbs free energies, and HOMOs and LUMOs of the two different conformations (twisted and planar) of the oligo-p-phenylenes were analyzed. The energy differences between the HOMOs and LUMOs of the substrates are in accord with the maximum absorption peaks of the experimental UV spectra of 2-6. The calculated normal vibrational modes of 2-6 were comparable with their experimental IR spectra.

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Section: Bcsupporting

confidence: 80%

“…29 Generally, in the solid phase, the oligophenyl structures planarize (dihedral angles starting from 2° to 18° [29][30][31][32][33] ). This fact is also reflected in smaller excitation energies in the absorption spectra obtained for films and crystals in comparison with solvent measurements.…”

Section: Bcmentioning

confidence: 99%

Calculated and Experimental UV and IR Spectra of Oligo-para-phenylenes

Park¹,

Lee²,

Yoon³

et al. 2014

Bulletin of the Korean Chemical Society

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“…It can be estimated roughly by Stark-shifted polarizability of the excited state 11 to be 10 Å, i.e., of the same order of magnitude of the intermolecular distance ͑about 5 Å͒ in the crystal. 29 The initial excited state has only 0.2 eV excess energy with respect to the optical gap, but due to the close molecular packing in the crystal this energy can be enough to allow disorder-assisted dissociation into pairs and following polarons. Polaron-polaron interaction may thus occur among free, highly mobile polarons, or by polaron exchange among adjacent pairs.…”

Section: Discussionmentioning

confidence: 99%

Ultrafast photogeneration mechanisms of triplet states inpara-hexaphenyl

et al. 1999

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We present femtosecond pump-probe measurements, both conventional and electric field-assisted, on organic light-emitting devices based on para-hexaphenyl. The dominant triplet exciton generation mechanism is assigned to nongeminate bimolecular recombination of photogenerated, spin-1 2 polarons. This process is active within a few hundred femtoseconds after photoexcitation and involves about 20% of the initially excited states. At higher photoexcitation densities, we observe an additional triplet generation mechanism, which occurs in the 10-ps time domain, due to fusion of singlet excitons and subsequent fission into correlated triplet pairs. The latter decay on the 10 2 -ps time scale by geminate recombination. ͓S0163-1829͑99͒01721-X͔

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“…Baudour et al [13][14][15] found an angle of 13°for pterphenyl, for p-quaterphenyl a mean torsional angle of 17.1°b etween the external ͑the first or the fourth͒ and the adjacent internal ͑the second or the third͒ phenyl rings, and a mean angle of 22.7°between the two internal rings. Sasaki 16 measured a torsional angle of almost 20°for p-quaterphenyl and Baker et al 17 obtained values between 20°and 30°. All of these measurements indicated that the oligomers crystallize in an alternately tilted structure: i.e., a structure in which all the odd numbered rings and all the even numbered rings are located in two planes tilted with respect to each other by the torsional angle.…”

Section: Introductionmentioning

confidence: 97%

First-principles calculation of the conformation and electronic structure of polyparaphenylene

Miao

Camp

Doren

et al. 1998

The Journal of Chemical Physics

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A first-principles density-functional calculation of the electronic and vibrational structure of the key melanin monomers J. Chem. Phys. 120, 8608 (2004) In this article, an all-electron first-principles total energy calculation with Gaussian-type functions for the wave functions, for the exchange correlation potential, and for the charge density has been applied for single chains of polyparaphenylene ͑PPP͒. A local-density approximation within a helical band structure approach has been used. The calculated torsional potential shows a minimum at the torsion angle of 34.8°. The internal coordinates were optimized in the equilibrium conformation and are in good agreement with experimental and other theoretical results. The calculated direct band gap is 2.54 eV compared with the experimental result from UPS spectra of 3.4 eV for the gas phase. The band structure strongly depends on the conformation which suggests that the electronic properties can be modified in a wide range through doping or addition of side groups.

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Crystal structures, phase transitions and energy calculations of poly(p-phenylene) oligomers

Cited by 356 publications

References 44 publications

Calculated and Experimental UV and IR Spectra of Oligo-para-phenylenes

Calculated and Experimental UV and IR Spectra of Oligo-para-phenylenes

Ultrafast photogeneration mechanisms of triplet states inpara-hexaphenyl

First-principles calculation of the conformation and electronic structure of polyparaphenylene

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