Jeff Mottishaw - Strengthening π-π  Interactions While Suppressing Csp2-H···π (T-Shaped) Interactions via Perfluoroalkylation: A   Crystallographic and Computational Study That Supports the Beneficial Formation of 1-D π-π Stacked   Aromatic Materials.

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      Publication Details (including relevant citation   information):

      Crystal Growth & Design 2012, 12 (11), 5655-5662.

      Abstract:

        The design and synthesis of aromatic crystalline materials with   controllable crystal structure packing is of particular interest   in organic semiconductor and optoelectronic devices, where 1-D   π–π stacked structures that enhance charge mobility are the most   beneficial. We report here that the π–π interactions between   aromatic molecules can be strengthened and the   Csp2–H···π   (T–shape) interaction can be suppressed by perfluoroalkylation of   corresponding aromatics. Both crystal structure data and ab   initio calculations show that the π–π interaction is strengthened   due to the electronic effects of perfluoroalkyl substituents, and   the Csp2–H···π   interaction is suppressed by the steric effects of the   perfluoroalkyl substituents. The Csp3–F···F–Csp3 attractive   interactions between perfluoroalkyl chains further stabilize the   crystal structures. We also found that Csp3–F···π   interaction can be eliminated if an optimal electron deficiency   of the π system is tuned by adjusting the number of   perfluoroalkyl substituents. The insight gained from this study   is of particular interest in organic semiconductor research as   well as the fields of molecular recognition, sensing, and design   of enzyme inhibitors where π–π interactions are also   important.

      Address (URL): http://pubs.acs.org/doi/abs/10.1021/cg301151u