Crystal Growth and Characterization of Fluorinated Perylene Diimides

One-dimensional crystals of fluorinated perylene diimides were achieved by the self-assembly of them via solvent-nonsolvent exchanging. The pi-conjugated fluorinated perylene diimides were assembled into highly-ordered nanostructures of well-defined morphologies in organic solvents due to the pi-pi interaction between the aromatic cores. It was found that With more introduced F atoms, perylene diimides showed remarkably improved solubility and thus were much easier to grow into crystals, due to the increased polarity induced by the strong electron-withdrawing F group. More importantly, single crystal of N,N'-diperfluorophenyl-3,4,9,10-perylenetetracarboxylic diimide(DPFPP) was obtained, and the unit cell-dimensions of triclinic structure were determined by the selected area electron diffraction(SAED) patterns to be a=0.712 nm, b=1.072 nm, c=2.914 nm, alpha=97.0 degrees, beta=89.6 degrees, gamma=93.4 degrees. Owing to most of the longest c-axis orienting nearly vertically to the long axis of the needle crystal, the molecular planes are expected to be vertical to the needle axis.