Bent-Core and Nematic Liquid Crystal Functionalized Gold Nanorods

Abstract

Gold nanorods (GNRs) functionalized with trimethoxysilane terminated nematic or bent-core liquid crystals (LCs) are described. In the first step, cetyltrimethylammonium bromide (CTAB) surfactant-stabilized GNRs were prepared using a single step, non-seeding method. The CTAB capping on the GNRs was then replaced in a two-step process first by binding of mercaptopropyltrimethoxysilane followed by immobilization of the nematic or bent-core LC silane by a dehydration condensation. The final LC-decorated GNRs were characterized by UV-vis-NIR spectrophotometry, IR spectroscopy and transmission electron microscopy (TEM). The functionalized nanorods were found to be stable, well dispersible in non-polar organic solvents. The bent-core LC-capped GNRs exhibited only short-range self-assembly after slow evaporation of the solvent on TEM grids. However, the nematic LC-decorated rods displayed regular patterns of self-assembled GNRs on TEM grids after annealing the sample in the presence of an external magnetic field.

Keywords:

• Bent-core liquid crystal
• nematic
• gold nanorods
• self-assembly

Acknowledgments

This work was financially supported by the Province of Manitoba, the NSF through a Center for Chemical Innovation, the Natural Sciences and Engineering Research Council (NSERC) of Canada, the Canada Foundation for Innovation (CFI), the Manitoba Research and Innovation Fund (MRIF). We would also like to thank Andre Dufresne for assistance with TEM imaging.