2024-03-28T20:38:03Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/194452020-05-29T08:17:24Zcom_10261_31com_10261_3col_10261_284
Optical, Redox, and NLO Properties of Tricyanovinyl Oligothiophenes: Comparisons between Symmetric and Asymmetric Substitution Patterns
Casado, Juan
Ruiz Delgado, M. Carmen
Rey Merchán, M. Carmen
Hernández, Víctor
López Navarrete, Juan T.
Pappenfus, Ted M.
Williams, Nathaniel
Stegner, William J.
Johnson, Jared C.
Edlund, Brett A.
Janzen, Daron E.
Mann, Kent R.
Orduna, Jesús
Villacampa, Belén
Electronic structure
Oligothiophenes
Photonics
Semiconductors
13 pages, 13 figures, 3 tables.
A series of tricyanovinyl (TCV)-substituted oligothiophenes was synthesized and investigated with a number of physical methods including UV/Vis, IR, and Raman spectroscopy, nonlinear optical (NLO) measurements, X-ray diffraction, and cyclic voltammetry. Mono- or disubstituted oligomers were prepared by the reaction of tetracyanoethylene with mono- or dilithiated oligomers. The comparative effects of the symmetric and asymmetric substitutions in the electronic and molecular properties have been addressed. These oligomers display dramatic reductions in both their optical and electrochemical band gaps in comparison with unsubstituted molecules. The analysis of the electronic properties of the molecules was assisted by density functional theory calculations, which are in excellent agreement with the experimental data. TCV substitution influences the energies of the frontier orbitals, especially with respect to the stabilization of LUMO orbitals. X-ray structural characterization of a monosubstituted oligomer exhibits -stacking with favorable intermolecular interactions. NLO results agree with the role of the intramolecular charge-transfer feature in the asymmetric samples. These results furthermore exalt the role of conformational flexibility in the disubstituted compounds and reveal an unexpected nonlinear optical activity for symmetric molecules. Regarding the electronic structure, the interpretation of the vibrational data reflects the balanced interplay between aromatic and quinoid forms, finely tuned by the chain length and substitution pattern. The electronic and structural properties are consistent with the semiconducting properties exhibited by these materials in thin film transistors (TFTs).
J.C. is grateful to the Ministerio de Ciencia y Tecnología (MCyT) of Spain for a Ramón y Cajal research position of Chemistry at the University of Málaga. The present work was supported in part by the Dirección
General de Enseñanza Superior (DGES, MEC, Spain) through the research projects BQU2003–03194 and BQU2002-00219. We are also indebted to Junta de Andalucía (Spain) (FQM-0159) and Gobierno de Aragón (E39) funding for our research groups. M.C.R.D. thanks the MEC of Spain for a personal grant. T.M.P. acknowledges a Grant-in-Aid
of Research, Artistry and Scholarship from the Office of the Dean of the Graduate School of the University of Minnesota.
Peer reviewed
2009-12-10T08:40:49Z
2009-12-10T08:40:49Z
2006-04-21
artículo
http://purl.org/coar/resource_type/c_6501
Chemistry - A European Journal 12(21): 5458 - 5470 (2006)
1615-9853
http://hdl.handle.net/10261/19445
10.1002/chem.200501389
en
http://dx.doi.org/10.1002/chem.200501389
none
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Wiley-VCH