Facile synthesis of gold nanoparticles capped with an ammonium-based chiral ionic liquid crystal

ABSTRACT

Herein, we describe a facile synthesis of stable chiral ionic liquid crystal (ILC)-capped gold nanoparticles. A new ILC containing a chiral cholesterol moiety having a terminal triethylammonium group was synthesised which exhibited an enantiotropic lamellar mesophase. Stable, monodisperse citrate-stabilised gold nanoparticles having a size of ~60 nm were prepared and the citrate ligands on the gold nanoparticles were replaced with chiral ILC through a two-phase ligand exchange process. The resulting chiral ILC-stabilised particles were characterised using UV–visible (UV–Vis) and transmission electron microscopy (TEM) studies. Different from the citrate-stabilised nanoparticles, the ligand exchanged gold nanoparticles were dispersible in organic solvent and resulting dispersion was stable for more than observed period of 3 months. Furthermore, the chiral ILC-decorated gold nanoparticles were found to be well dispersible in a nematic host without any aggregation and induced a vertical alignment of the nematic director.

GRAPHICAL ABSTRACT

KEYWORDS:

• Ionic liquid crystal
• chiral phase
• lamellar
• gold nanoparticles
• ligand exchange
• doping

Acknowledgments

SU acknowledges Science and Engineering Research Board, Department of Science and Technology, New Delhi [Grant Number ECR/2015/000419] for financial support through Early Career Research award. Authors acknowledge National Institute of Technology, Tiruchirapalli, for helping in DSC studies.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data can be accessed here.

Additional information

Funding

SU acknowledges the Science and Engineering Research Board, DST, New Delhi [Grant Number ECR/2015/000419] for financial support through Early Career Research award.