jp0267104_si_001.pdf (3.78 MB)
One- and Two-Photon Spectroscopy of Donor−Acceptor−Donor Distyrylbenzene Derivatives: Effect of Cyano Substitution and Distortion from Planarity
journal contribution
posted on 2002-11-02, 00:00 authored by Stephanie J. K. Pond, Mariacristina Rumi, Michael D. Levin, Timothy C. Parker, David Beljonne, Michael W. Day, Jean-Luc Brédas, Seth R. Marder, Joseph W. PerryThe one- and two-photon spectroscopic properties of four symmetrically substituted donor−acceptor−donor
distyrylbenzenes with either di-n-butyl- or diphenylamino donor groups and cyano acceptor groups are reported.
It has been found that the position of the substitution of the electron-withdrawing cyano groups on the central
phenylene ring as compared to the vinylene bond strongly affects the observed properties. In particular, the
molecules with cyano substitution on the α-carbon of the vinylene linkage are characterized by weak
fluorescence, short fluorescence lifetimes, and two-photon cross sections (δ) that are comparable to analogous
molecules with no acceptor groups. In contrast, the molecules with acceptor substitution on the central phenylene
ring are strongly fluorescent and have δ values roughly twice those of the vinyl-substituted molecules. These
results are discussed in terms of the larger deviation of the conjugated backbone from planarity and the
smaller distance between the donors and acceptors when the cyano groups are substituted on the vinylene
carbon rather than the central phenylene ring.