Quasi-crystals (supramolecular)

The supramolecular Quasi-crystals are produced in photochemical reaction by exposing solutions of photochromic spiropyran molecules to UV radiation.

The quasi-crystals have external shape of submicron globules and their internal structure consists of crystals enveloped by an amorphous matter (see Fig.

[2][3][4] In an applied electrostatic field, quasi-crystals form macroscopic threads that show linear optical dichroism.

[1][5] Later Krongauz described unusual phase transitions of molecules composed of mesogenic and spiropyran moieties, which he named "quasi-liquid crystals."

A micrograph of their mesophase appeared on the cover of Nature in a 1984 paper, “Quasi-Liquid Crystals.”[6] The investigation of spiropyran-merocyanine self-organized systems, including macromolecules (see, for example, Fig.

Scheme 1. Formation of merocyanine dipoles upon irradiation
Figure 2. Illustration of Self-Assembling Spiropyran Polymers by Zipper Crystallization [ 7 ]