Odd liquid crystallyne dimers can be linear

The crystal and molecular structures of two liquid crystalline symmetric dimers containing the mesogenic group alpha,alpha'-dimethylbenzalazine and flexible polymethylenic spacers of different parity (even and odd) are reported. They show nematic phases with strong odd-even effects. The unusual result we have found is that the odd dimer crystallizes adopting a molecular conformation in which the two mesogenic groups are aligned with respect to each other, as for the even dimer. The crystal packing of the two dimers is also analogous.