Liquid crystal glycolipids - Carbohydrate Chemistry: Chemical and Biological Approaches - page 331

have molecular architectures where the head group has two separately
identifiable sugar groups attached to a single aliphatic chain. One
family of synthesized materials designed in this way is the N,N-bis-
( D -mannitolyl)alkylamides, which have acyclic sugar units. For these
materials the total head group size is large enough to induce curvature
into the molecular packing, but in the opposite direction in comparison
to the cerebrosides and archael glycolipids. Therefore, it was not be
surprising that these materials were found to exhibit columnar phases,
see Table 4, 30 only the head groups are on the outsides of the columns.
In order to investigate the effects of curvature in these systems further,
a Gibbs' binary phase diagram for mixtures of N,N-bis-( D -mannitolyl)-
dodecylamide (two heads one tail, columnar), A, with octadecanoyl
D -galactocerebroside, B, (two tails one head, columnar) was investigated,
see Fig. 20. It was found that as the phase diagram was traversed as a

Table 4 Transition temperatures ( 1 C) as a function of chain
length (n) for the N,N-bis-(D-mannitolyl)alkylamides.

n mp Col Iso Liq

8 104.1 144.3

9 145.6 157.5

11 148.9 170.2

13 147.8 183.0

Fig. 20 Miscibility phase diagram (wt%) as a function of temperature ( 1 C) between
N,N-bis-( D -mannitolyl)dodecylamide (A) and octadecanoyl D -galactocerebroside (B).