Herein, we report a systematic theoretical investigation of the molecular and electronic properties of unsubstituted polytriacetylene (PTA) and iso-polytriacetylene (iso-PTA) oligomers, which are characterized by through and cross pi-conjugation pathways, respectively. The goal of the study is to compare through versus cross conjugation on the basis of the computed molecular geometries of the neutral, anionic, and cationic species, the electron affinities, ionizaiton potentials, excitation energies, and nonlinear optical properties for oligomers up to the nonamer. Differences in the effective conjugation length are directly related to electron delocalization in cross- and through-conjugated pathways. As in the through-conjugated oligomers, that is, the PTAs, the frontier orbitals of the ios-PTA oligomers are delocalized along the entire carbon backbone, suggesting that pi-delocalization can extend through cross-linked carb on atoms. However, in contrast to the PTA oligomers, the bond lengths remain strictly constant and the reduction of the energy gap beyond the trimer is completely due to the correlation contribution. On the other hand, in the anions and cations, the bond lengths do change significantly with increasing chain length. Therefore, oxidation or reduction of the iso-PTA oligomer appears to switch on delocalization through cross-linked carbon atoms. Obviously, the effective conjugation length is specific and depends on the observable considered

Bruschi, M., Giuffreda, M., & Luethi, H. (2005). Through versus cross electron delocalization in polytriacetylene oligomers: A computational analysis. CHEMPHYSCHEM, 6(3), 511-519 [10.1002/cphc.200400202].

Through versus cross electron delocalization in polytriacetylene oligomers: A computational analysis

BRUSCHI, MAURIZIO;
2005-03

Abstract

Herein, we report a systematic theoretical investigation of the molecular and electronic properties of unsubstituted polytriacetylene (PTA) and iso-polytriacetylene (iso-PTA) oligomers, which are characterized by through and cross pi-conjugation pathways, respectively. The goal of the study is to compare through versus cross conjugation on the basis of the computed molecular geometries of the neutral, anionic, and cationic species, the electron affinities, ionizaiton potentials, excitation energies, and nonlinear optical properties for oligomers up to the nonamer. Differences in the effective conjugation length are directly related to electron delocalization in cross- and through-conjugated pathways. As in the through-conjugated oligomers, that is, the PTAs, the frontier orbitals of the ios-PTA oligomers are delocalized along the entire carbon backbone, suggesting that pi-delocalization can extend through cross-linked carb on atoms. However, in contrast to the PTA oligomers, the bond lengths remain strictly constant and the reduction of the energy gap beyond the trimer is completely due to the correlation contribution. On the other hand, in the anions and cations, the bond lengths do change significantly with increasing chain length. Therefore, oxidation or reduction of the iso-PTA oligomer appears to switch on delocalization through cross-linked carbon atoms. Obviously, the effective conjugation length is specific and depends on the observable considered
Articolo in rivista - Articolo scientifico
Scientifica
DENSITY-FUNCTIONAL THERMOCHEMISTRY; DIFFERENTIAL-OVERLAP TECHNIQUE; TRANSITION-METAL-COMPLEXES; INTERMEDIATE NEGLECT; CONJUGATED OLIGOMERS; MOLECULAR WIRES; CONDUCTING POLYMERS; EXCITATION-ENERGIES; NONLINEAR OPTICS; RAPID ROUTE
English
Bruschi, M., Giuffreda, M., & Luethi, H. (2005). Through versus cross electron delocalization in polytriacetylene oligomers: A computational analysis. CHEMPHYSCHEM, 6(3), 511-519 [10.1002/cphc.200400202].
Bruschi, M; Giuffreda, M; Luethi, H
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/10281/13884
Citazioni
  • Scopus 17
  • ???jsp.display-item.citation.isi??? 17
Social impact