Synthesis of fluorinated anti-fluorenacenedione and the structural, electronic, and field-effect properties

Fluorinated anti-. fluorenacenedione 6 was newly synthesized by oxidation of a dehydro[ 12] annulene fused with tetra. fluorobenzene 4. X- Ray crystallography of 6 demonstrated a totally planar structure and shorter intramolecular distances for F center dot center dot center dot I, F center dot center dot center dot O, and I center dot center dot center dot O than the corresponding sums of van der Waals ( vdW) radii. In the packing structure, molecules are arranged in a pi- stacked motif, and the intermolecular distances between heavy atoms ( C center dot center dot center dot I, C center dot center dot center dot F,C center dot center dot center dot O, F center dot center dot center dot I, and center dot center dot center dot O) of the adjacent columns are also shorter than the corresponding sums of vdW radii, indicating highly dense packing for the crystal structure of 6. In the F-19 NMR spectrum of 6, a signal for the fluorine atom adjacent to iodine exhibited downfield shift by 29 - 40 ppm as compared with the other three signals. This is attributed to the intramolecular short contact between F and I atoms, which is supposed to cause a donor - acceptor interaction. Cyclic voltammetry of 6 exhibited two reversible reduction waves at E-1/2 2 =- 0.91 and - 1.45 V vs. Fc/ Fc(+). A thin. film of 6 was prepared by vacuum deposition and was applied to a field- effect transistor ( FET) device, which exhibited n- type transistor responses although the mobility was not very high.