Controlled Morphological Arrangement of Anisotropic Nanoparticles via Oxidation or Ionic Cross-Linking

Abstract

For a long time, researchers in nanochemistry have been exploring ways to create 3D structures using cross-linked nanoparticles, such as lyogels and aerogels. In the present work, how simple modifications to the nanoparticle surface can be used to influence the resulting structure in a targeted manner is demonstrated. Specifically, positively charged surface ligands containing amine groups are compared to negatively charged ligands typically used, containing carboxylic acid groups, to generate network structures using different gelation agents. By utilizing bridging through S2− ions, a network structure of anisotropic CdSe/CdS nanorods is generated, packing them side by side at the nanoscopic level. The resulting structures exhibit improved fluorescence properties comparable to those of tip-to-tip connected networks but without harsh conditions for the nanoparticle surfaces. This innovative new method of gelation using S2− ions can achieve adequate photoluminescence quantum yields as well as prolonged fluorescence lifetimes compared to other network structures.