One- and Two-Photon Spectroscopy of Donor−Acceptor−Donor Distyrylbenzene Derivatives:  Effect of Cyano Substitution and Distortion from Planarity 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. Perry 10.1021/jp0267104.s001 https://acs.figshare.com/articles/journal_contribution/One-_and_Two-Photon_Spectroscopy_of_Donor_Acceptor_Donor_Distyrylbenzene_Derivatives_Effect_of_Cyano_Substitution_and_Distortion_from_Planarity/3724560 The one- and two-photon spectroscopic properties of four symmetrically substituted donor−acceptor−donor distyrylbenzenes with either di-<i>n</i>-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 (<i>δ</i>) 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 <i>δ</i> 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. 2002-11-02 00:00:00 vinylene diphenylamino donor groups molecule substitution fluorescence phenylene ring cyano acceptor groups