Optically Active Liquid Crystalline Polyoxometalates via Electrostatic Encapsulation with Cholesterol-Containing Amphiphile

Chem Asian J. 2016 Jul 20;11(14):2001-5. doi: 10.1002/asia.201600532. Epub 2016 Jun 17.

Abstract

A novel cholesterol-containing amphiphile was designed and prepared in the study, which is a room-temperature ionic liquid crystal over a broad temperature range with pronounced chiroptical properties. Four types of inorganic polyoxometalates (PMs) with different numbers of charges were encapsulated by the chiral amphiphile. The incorporation of chiral organic cations triggers achiral PMs in the complexes to show induced chirality through intermolecular interactions, as demonstrated by circular dichroism spectroscopy. The electrostatic encapsulation with mesomorphic promoters provides the inorganic PMs with liquid crystalline behavior, characterized by differential scanning calorimetry, polarized optical microscopy, and X-ray diffraction. The strategy applied herein represents a unique example of liquid crystalline PM complexes with optical activity.

Keywords: amphiphiles; liquid crystals; optical activity; polyoxometalates; supramolecular self-assembly.