Quasi-liquid crystals

There are provided compounds which give quasi-liquid crystals, which comprise a mesogenic group, which can contain bridging groups, a bridging group and a spiropyran moiety having a 2H pyran ring, a terminal group being attached to the mesogenic group. The mesogenic group contains two aromatic, heterocyclic or cycloaliphatic ring structures. The compounds are prepared by a coupling reaction of mesogenic groups with a spiropyran compound via a suitable bridging group. There is provided a process for producing quasi-liquid crystalline (QLC) films which are useful for producing a wide variety of devices based on the optical non-linearity of generation of second harmonics by such films. Such devices can also be based on ferroelectric, pyroelectric, piezoelectric effects and photoactivity of such oriented QLC films.