Bent-Core and Nematic Liquid Crystal Functionalized Gold Nanorods

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.