Arene-perfluoroarene interactions in crystal engineering: structural preferences in polyfluorinated tolans

Smith, C.E.; Smith, P.S.; Thomas, R.L.; Robins, E.G.; Collings, J.C.; Dai, C.Y.; Scott, A.J.; Borwick, S.; Batsanov, A.S.; Watt, S.W.; Clark, S.J.; Viney, C.; Howard, J.A.K.; Clegg, W.; Marder, T.B.

Abstract

The compounds 4-ROC6F4C[triple bond, length as m-dash]CPh (4) where R = Me (a), Et (b), Prn (c), Pri (d), Bun (e), n-C5H11 (f), PhCH2 (g), PhCH2CH2 (h), 4-MeC6H4 (i), 4-EtC6H4 (j) and menthyl (k), have been prepared by reaction of C6F5C[triple bond, length as m-dash]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[triple bond, length as m-dash]CPh·C6F5C[triple bond, length as m-dash]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/C6F5 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.

• Journal Article Type: Article
• Publication Date: 2004
• Journal: Journal of Materials Chemistry
• Print ISSN: 0959-9428
• Electronic ISSN: 1364-5501
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 14
• Issue: 3
• Pages: 413-420
• DOI: https://doi.org/10.1039/b314094f
• Public URL: https://durham-repository.worktribe.com/output/1600820