Core-controlled formation of micellar cubic assemblies of supramolecular dendrimers: From their mechanism to formation of gold nanostructures

Abstract

We prepared gold nanostructures from a taper-shaped supramolecular material (1-COOH) containing a carboxylic acid (-COOH) core, rigid biphenylene group, and three perfluorinated (-CF3) tails. The carboxylic core of the supramolecule serves as the site for reaction with the metal ions. We show that the self-assembling behavior of the material is strongly affected by substituting the carboxylic core of the supramolecule with a Na+ ion, followed by ion transfer of Au-III and subsequent reduction of AuIII with UV irradiation. Synchrotron X-ray diffraction (XRD) results show that the structure of 1-COOH solution (THF) and [1-COO--Na+] complex is disordered. However, the [1-COO--(AuCl3)-Cl-III](-) complex before UV irradiation exhibits liquid crystalline order with micellar cubic assemblies. This order and spacing are preserved during reduction of the metal salt with UV irradiation, although the intensities of the peaks increase. UV-visible spectra and transmission electron microscopy (TEM) images show the generation of the gold arrays in the presence of the supramolecular building block. Moreover, the size and shape of gold nanocrystals are controllable depending on UV irradiation time. These types of perfluorinated supramolecular templates have enhanced mesophase stability on account of the existence of strong intermolecular interactions, although many of these molecules are not traditional amphiphiles.