Routes to the preparation of mixed monolayers of fluorinated and hydrogenated alkanethiolates grafted on the surface of gold nanoparticles

Abstract

The use of binary blends of hydrogenated and fluorinated alkanethiolates represents an interesting approach to the construction of anisotropic hybrid organic-inorganic nanoparticles since the fluorinated and hydrogenated components are expected to self-sort on the nanoparticle surface because of their reciprocal phobicity. These mixed monolayers are therefore strongly non-ideal binary systems. The synthetic routes we explored to achieve mixed monolayer gold nanoparticles displaying hydrogenated and fluorinated ligands clearly show that the final monolayer composition is a non-linear function of the initial reaction mixture. Our data suggest that, under certain geometrical constraints, nucleation and growth of fluorinated domains could be the initial event in the formation of these mixed monolayers. The onset of domain formation depends on the structure of the fluorinated and hydrogenated species. The solubility of the mixed monolayer nanoparticles displayed a marked discontinuity as a function of the monolayer composition. When the fluorinated component content is small, the nanoparticle systems are fully soluble in chloroform, at intermediate content the nanoparticles become soluble in hexane and eventually they become soluble in fluorinated solvents only. The ranges of monolayer compositions in which the solubility transitions are observed depend on the nature of the thiols composing the monolayer.

Patchy and Janus Nanoparticles by Self-Organization of Mixtures of Fluorinated and Hydrogenated Alkanethiolates on the Surface of a Gold Core

“…Gold nanoparticles NP-C16/F6, NP-C8/F6, and NP-brC12/ F6 were prepared by direct synthesis, whereas NP-C12/F6 and NP-C12/F10 were obtained by place exchange reaction from narrowly dispersed NP-C12, in turn prepared following the method of Miyake. 32 Synthetic details are reported in ref 29 and, for additional nanoparticles, in the Supporting Information (SI). All samples were fully characterized using UV−vis, transmission electron microscopy (TEM), thermogravimetric analysis, and standard NMR experiments.…”

“…The detailed synthetic procedures for the preparation of gold nanoparticles NP-C16/F6, NP-C12/F6, NP-C12/F10, NP-C8/ F6, and NP-brC12/F6 are reported in ref29. Synthesis of NP-C8/F6-i and NP-C8/F6-p systems is given in full in the SI.…”

Gold nanoparticles with patterned surface monolayers for nanomedicine: current perspectives

“…In further work, using simpler fluorinated (F) and hydrogenated carbon (H) thiols, the same group obtained a comprehensive framework of monolayer morphologies by systematically varying the structure, relative length, steric bulk, and ratio of the mixing ligands (Şologan et al. 2016a , b ; Fig. 3 ).…”

“Precipitation on Nanoparticles”: Attractive Intermolecular Interactions Stabilize Specific Ligand Ratios on the Surfaces of Nanoparticles

“…Unfortunately, predicting the composition of mSAMs is not an easy task, and the assumption that the molar ratio of ligands in solution will be preserved on NPs is often wrong . The discrepancy between the solution ratio and the surface ratio can stem from intermolecular interactions between the ligands, solvation effects, the steric bulkiness of the ligands, and so on. Herein, we studied the competitive adsorption of two novel thiol ligands onto gold NPs.…”