The compounds 4-ROC6F4C=Ph (4) where R = Me (a), Et (b), Prn (c), Pri (d), Bun (e), W-C5H11 (f), PhCH2 (g), PhCH2CH 2 (h), 4-MeC6H4 (i), 4-EtC6H 4 (j) and menthyl (k), have been prepared by reaction of C 6F5C=CPh (3) with ROH in the presence of KOH, and characterised by NMR (1H, 13C, 19F) and mass spectroscopy. The single-crystal structures of PhC=CPh·C 6F5C=CC6F5 (1:2), 3 and 4a,c,d,f,g,i have been determined by X-ray diffraction at 120-160 K, and that of 3 also calculated by an ab initio pseudo-potential DFT method. The tolan moiety is nearly planar in each molecule except 4a, which has a Ph/C 6F5 dihedral angle of 25.8°. The R group adopts an out-of-plane orientation except in 4f, where the n-pentyl chain is nearly coplanar with the C6F5 group at the cost of severe distortion of the C(ar)-C(ar)-O angles (which differ by 13.5°). The structures of 1:2, 3 (pseudo-isomorphous with 1:2), 4a, 4g (disordered) and 4i contain stacks of alternating arene and perfluoroarene moieties; 4c and 4d form discrete centrosymmetric dimers with arene/ perfluoroarene overlap, while 4f forms infinite stacks without such overlap. Differential thermal analysis and transmitted polarised light microscopy revealed no liquid-crystalline behaviour of 3 and 4.
|Number of pages||8|
|Journal||Journal of Materials Chemistry|
|Publication status||Published - 7 Feb 2004|