The effects of the π–π stacking interactions on the patterns of gold nanoparticles formed at the air–water interface

Abstract

Benzyl-n-hexadecyl dimethylammonium chloride (BHDC) monolayer-stabilized gold nanoparticles were synthesized in a two-phase liquid–liquid system and found to self-assemble into varied structures under the control of temperature at the air–water interface. It has been demonstrated that the π–π stacking interactions between the capping agent molecules significantly affect the formation of the unique patterns. A possible mechanism based on Marangoni–Bénard convection in the evaporating droplets and π–π stacking interactions was proposed. Four surfactants with similar structures: N-hexadecyl-N-methylpyrrolidinium bromide (C₁₆MPB), 1-hexadecyl-3-methylimidazolium bromide (C₁₆mimBr), 1-(2,4,6-trimethylphenyl)-3-hexadecylimidazolium bromide (C₁₆pimBr) and hexadecyltrimethylammonium bromide (CTAB) were also used to further verify the formation mechanism mentioned above.