Halogen Bonding in Crystal Engineering - Halogen Bonding: Fundamentals and Applications - page 119

Fig. 7 Linear 1D infinite chains formed on self-assembly of bidentate and self-
complementary modules where donor and acceptor sites axes are parallel and coaxial ( A ),
of bidentate donor and acceptor modules where donor and acceptor sites axes are paral-
lel and coaxial ( B ), or are parallel and translated from each other in the XB donor ( C )or
acceptor ( D ) module, respectively

DITFB/1,4-bis( N , N -dimethylamino)benzene [64], diiodobutadiyne/dicyano
and diiodobutadiyne/dipyridyl derivatives [80, 81]). Similarly, the stepped in-
finite chains geometry is obtained when XB acceptor tectons with collinear
sites interact with stepped XB donors. Examples are the chains formed by TIE
(e.g. with phenazine [129]), by ( E )-1,2-diiododifluoroethene (e.g. with 1,4-
BPY[164]),andby -diiodoperfluoroalkanes, or their dibromo analogues

(e.g. with 1,4-BPY, pyrazine and its derivatives) wherein the perfluoroalkyl
chain typically adopts a trans conformation along the carbon chain [124,
165-167]. Stepped 1D networks are generated also on self-assembly of tec-
tons, both of which have parallel and translated binding sites (e.g.

α , ω

α , ω -

dicyanoalkanes/ -diiodoperfluoroalkane adducts [168] and TMEDA/( E )-

1,2-diiododifluoroethene adduct [164]).
When the binding sites axes on starting modules are not parallel but form
an angle, the resulting self-assembled chains assume a herringbone arrange-
ment, the angles along the chain corresponding to the angles of binding sites

α , ω