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Vibrational and Quantum‐Chemical Study of Nonlinear Optical Chromophores Containing Dithienothiophene as the Electron Relay
Author(s) -
Casado Juan,
Hernández Víctor,
Kim OhKil,
Lehn JeanMarie,
López Navarrete Juan T.,
Delgado Ledesma Salvador,
Ponce Ortiz Rocío,
Ruiz Delgado Mari Carmen,
Vida Yolanda,
PérezInestrosa E.
Publication year - 2004
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200305752
Subject(s) - intramolecular force , chromophore , acceptor , chemistry , electron acceptor , raman spectroscopy , photochemistry , density functional theory , electron donor , electron transfer , conjugated system , electron , chemical physics , computational chemistry , stereochemistry , physics , organic chemistry , polymer , optics , catalysis , quantum mechanics , condensed matter physics
Abstract A series of nonlinear optical (NLO) donor–acceptor (D–A) chromophores containing a fused terthiophene, namely dithienothiophene ( DTT ), as the electron relay, the same donor group, and acceptors of various strengths, has been investigated by means of infrared and Raman spectroscopies, both in the solid state as well as in a variety of solvents, to evaluate the effectiveness of the intramolecular charge transfer from the electron‐donor to the electron‐acceptor end groups. The Raman spectral profiles of these NLO‐phores measured from their dilute solutions have been found to be rather similar to those of the corresponding solids, and thus their intramolecular charge transfer (ICT) shows very little dependence on the solvent polarity. The experimental results obtained for the DTT ‐containing NLO‐phore with a 4‐( N , N ‐dibutylamino)styryl end group as the donor and a 2,2‐dicyanoethen‐1‐yl end group as the acceptor differ from those previously obtained for two parent “push–pull” chromophores with the same D–A pair but built‐up around either a bis(3,4‐ethylenedioxythienyl) (BEDOT) or a bithienyl (BT) electron relay. Vibrational spectroscopy shows that DTT is significantly more efficient as an electron relay than BT (which has the same number of conjugated CC bonds) or BEDOT (which can be viewed as a rigidified version of BT on account of noncovalent intramolecular interactions between heteroatoms of adjacent rings). Density functional theory (DFT) calculations have also been performed on these NLO‐phores to assign their main electronic and vibrational features and to obtain information about their structures. An additional merit of these molecular materials was revealed by the infrared spectra of the DTT ‐based NLO‐phores recorded at different temperatures. Thus, spectra recorded between −170 and 150 °C did not show any substantial change, indicating that the materials have a high thermal stability, which is of significance for their use as active components in optoelectronic devices.